Get in touch
If you have any general questions or comments you feel might benefit other people as well, I encourage you to post a comment on a relevant page, or use the forum! You can also send me an email by using the address mark at unsigned dot io. I encourage you to use my PGP key, that is posted in the sidebar on this page!
Hello I’m IN3AQK,
I’ve just placed an order for a MicroModem DIY Kit, but ufortunately I’ll probably misunderstand something.
Could I use it connected to a normal Arduino Uno or Arduino Micro.
Or the forms factor is for other arduino boards?
Paolo
Hi Paolo!
You can use it just fine with a normal Arduino UNO. In fact, it will work with any Arduino compatible board that has the ATmega328p microcontroller 🙂 A small guide with an example of how to connect the kit to an Arduino is included in the kit, it’s very easy. You just connect a few wires from the MicroModem board to the Arduino pins, and everythings ready!
Perfect, thanks for the info.
The form factor for which type of arduino is? In the site I’ve seen a photo of the board stacked on an square arduino board. Where I can eventually buy it?
The board form factor fits perfectly into a MicroDuino, you can see them here: https://www.microduino.cc/module/view?id=53d89a05c69eee000055f525
I am packing your order now, and sending it out today 🙂
Thanks, really nice Paolo
Another question, which version of microduino is more suitable for the Micromodem, 5Volt one or 3,3Volt
Thanks
Definitely go for the 5V version, as it is running at 16MHz. The 3.3v one is only 8MHz. All the code I have published expects a 16MHz operating frequency, so you would have to change that yourself if you go for 8 🙂
Hello
Assembled modem kit
but question how to do load firmware APRS modem to Microduino core with USB module
??
Xloader OK ?
OK )) no answers but now all done and work
Hey! Sorry about that, but I am having some very busy days at work, just came home from a 13 hour work day 😉 Glad you got it working!
i build it myself, but i think i miss some points, in the schematic, i dont understand witch lines cross and witch not, only in one cross is a point, that tells me to connect…
the line in and mic out part works, but i good ptt always pushed on my baofeng, same as you used, but my cable is fine, use it on a tnc2s as well.
but the thing is, i checked the mosfet circul and it seems fine, wenn i not send i have no bridge between – and ptt, when i send i have one, but on the ptt wire is a negativ -0.5v it shud be 3v + right?
got it to work, it turns out that i connect the 2n7000 wrong. but it seems to receive not all on the air, my tnc2s get more packets, maybe is it possible to put a poti in it?
I see Microduino-OLED on stock
can we use it ?? will be fine with micromodem
Thanks
Should be good, but I’m not making any guarantees 😉 Take a look at the forum post by Taner though, I’m pretty sure that was the OLED he used for his build!
Awesome project! Do you ship to the US?
Thanks
Hi Nate!
Thanks! I do ship to the US 🙂
Urgent Opportunity
Could you please make contact asap in order to discuss the potential for large scale procurement of this product?
Kind Regards!
what is delivery costs to denmark ?
yours Bent
Hi Bent! It’s just the standard 3.5€, or about 26 kroner. Or you can select “Local Pickup” and pick it up yourself, if you’re close to Ringsted 🙂
Hey there, what a great project you have managed to accomplish!!
I’ve been looking forward to implement this amazing modem myself with the help of your tutorial and the repository in GitHub, not sure of what am i doing wrong but i don’t seem to even compile the proyect.
Is there any way i can do it with the Atmel Studio (Visual micro) plugin? (same as arduino IDE i guess).
I would really apreaciate any help i can get!
Regards!
Hi Andrés! I’m guessing from your forum posts that you got the compilation working. If not, hit me up in the forum and I’ll help you get the build environment set up 🙂
MicroAPRS config Serial port, however, Serial 38400 bps, 115200 bps or .HEX compiler program.
kiss mode
Hi Niphon!
I’m not quite sure what you mean? Are you having troubles flashing a compiled firmware to the modem, or do you want to change the serial baud rate of the firmware?
HI Markqvist
change the serial baud rate of the firmware
Ah, just have a look in the “device.h” file. Then change the line:
#define BAUD 9600
To:
#define BAUD 115200
And compile the firmware! That’s all you need to do to change the baud!
Hello,
we are a B2B Trader in Austria.
For a big austrian industry company we need one of your products as followed:
3 pieces MicroModem r23g with Pin Connectors
Can we buy it directly from you? And can you send us a proforma invoice sio we can pay it immediatly!
How long will be the shipping time?
Kind Regards
Eva
Can this interface with a GPS such as the Ultimate GPS?
Can you provide example code and schematics for configuring with a GPS.
Thank You
Den
Hi Den!
As far as i know, the Ultimate GPS board just outputs the GPS data over a standard serial port, so that should be no problem. I don’t have one myself, so can’t provide exact code for it, but it should be pretty straight forward: Just poll the serial port for incoming data and parse the lat/lon values from it. Then set them using the commands in the library and transmit a position update!
I would like to use via tcp ip
with one Arduino .
Work? .
receive rx aprs stations
only the display 16×2
what value ? Do you send to Brazil
py2fg@uol.com.br
Hi Wladimir!
I can send to Brazil no problem! I’m not quite sure what you mean by wanting to use TCP/IP though? Do you want to receive APRS data from the internet and the send it over a serial connection to display the data on an LCD display? If so you actually don’t really need the modem, since there would be no need for demodulating a signal. You would already have the data directly available. If I misunderstand you, please elaborate 🙂
Hi, starting to see a few projects being done based around your modem, and I want to try a few for myself
Any time frame when the DIY kits will be in stock? or a parts list for just the empty PCB?
any idea what shipping to the U.S. would be?
Thanks
Hello, I need to get in contact to you to buy some micromodems.
Here in Costa Rica, we will launch a LEO satellite. Data came ashore using a link APRS radio.
I need to install micro modems in some hills in the country, in order to recover the satellite. This activity will be done in August, the event is call Campus Party, it’s a Technology Trade Show for hobbyist and makers. The webpage of the event is: http://costarica.campus-party.org/
We have a few weeks to setup the APRS network and the satellite.
Best regards.
Luis.
Sent you an email 🙂
Hello,
I am experimenting with APRS and arduino.
Is there a code or hex file available to flash my arduino (uno) and recieve aprs packages.
Frist i want to recieve aprs packages and put them on a maps (like aprs.fi)
Later on I want to send gps coordinates back to the first modem; do you have experience with gps coordinations?
Does anyone in the United States sell these? If not, what is shipping to United States Zip Code 83869-0625?
Hi Shawn!
There’s currently no resellers in the US, but I have them back in stock now. Shipping to the US is only 3.5€ without tracking. If you want it as a registered package with tracking, it’s a bit more expensive at 37€.
Hi
We wanna buy one micro modem for use in NearSpace Project. It is available ?
thanks
They are available again now, if you still need one 🙂
Hi,
i will order MicroModem, tell me is coming with something like box or wires and how much will cost shipping to Macedonia.
Thanks
Shipping is 3.5€ for unregistered airmail. Currently not any case or wires included, but I do have a prototype case I can send with it if you order one 🙂
i just ordered, please you do rest 🙂 ..i support you on this
Did you have also MicroModem DIY Kit ? because i want to order also that ? i just ordered Microduino, so i was mean to order and other DYI Kit from you 🙂
Your package is on it’s way 🙂 And with a little extra surprise 🙂 I don’t have any more of the DIY kits left. Maybe I will order more PCBs for them at some point, but I don’t know when.
Thanks Petersen i will make then because in github there is everything
I just got it…. well man… this is perfect… also case for modem is awesome 🙂 thanks a lot.
I’m happy to hear that! Thanks a bunch and enjoy!
When will the Micromodem be back in stock? I would like to purchase a couple more.
Thanks,
Hi Mark, i will need one MicroModem DIY Kit , do you have still that ? i want to order one with case for that and audio pins 🙂
Hi Bosko!
Unfortunately I don’t have any more of the PCBs left. I might have a new batch made if there is enough interest from people for the kits.
Do you know when you will have the micromodem back in stock? I would like to order one.
Thanks,
I want 2 MicroModem DIY Kit 🙂
I would be interested in about 4 kits as well! Please email me if you get them in!
I have new orders in at the PCB fab, and also for components, but probably wont have stock until late december. I usually make 50 piece batches, but I’m upping the next one to a couple hundred probably since they sell out quite quickly 🙂
Still not decided on doing another run of DIY kits, but will post if I do 🙂
I would like to order one micromodem. When will you have them in stock again?
Thanks,
i want 4 Micromodem DIY Kit …. 😉
hi,how can I buy the micromodem MDMRC23B ?
contact me at: info@spesimpianti.it
thank you
The modems will be back in stock soon, please check out the latest post on the blog 🙂
Do you still have these in stock?
http://www.dxzone.com/db1nto-aprs-transceiver/
If so, how much do they cost and how do I order a complete unit? What kind of antennae for a High Altitude Balloon would you recommend? I am currently using a J Pole.
Currently doing research on building a cubesat and since we’re using only commercial off the shelf parts this modem seems like a great way to get our telemetry data back to the ground station. Being completely new to this I had a question. Would it be feasible to cut out the modem usb –> computer connection and have the actual arduino supply the data that we would like transmitted (if we had sensors recording data also connected to the Arduino) or would that be too much to handle for something like the Arduino Uno? If that isn’t possible I was thinking I could connect the modem via USB to another microcontroller (if possible) but we’re trying to minimize power consumption by doing it all on one board.
You can easily bypass the USB connection! If you buy the modems from here you can use the UART port directly on the modem for a direct serial connection to another arduino for example. If you build it yourself, just be sure to add some connectors for the serial pins!
Hi Mark,
congrats, good work! I like to order one modem. Is there a chance to get one?
73 de Mark
They’ll be back in stock soon, check out the blog 🙂
Hello, looking to purchase two MicroModems + Shipping to USA, please send me quote to my e-mail. Thanks
Hi Mark,
first of all again congrat to your excellent work! It’s a lot of fun building things around… I just have a question, after running a coulpe hours the MicroModem the Path change by itself for example ti “WIDE1-1,9-2”. Any ideas?
73 Mark
Hello !
I have a question how to draw more shapes and letters.
Please help !
Best “ARDULASER” project !!
Hi Mark,
I need your help. Last year I bought a Micromodem rev1 A1 board from you.
I lost the manual that show me what pins to connect to the arduino nano. please
let me know if there is a pdf file for this. thanks for your time.
73’s de NP4ZB/JORGE
Hi Jorge! I made a collection of all the documentation of the old rev1 board and uploaded it here:
http://unsigned.io/wp-content/uploads/2016/02/Rev1Docs.zip
The specific documents you are interested in are “Pinout.pdf” and “Usage.pdf” 🙂 Hope it helps!
Hello,
Can you please recommend a micro transceiver dev board that work with 144.390 or could use per programmed 2-Meter freq.
KM4QDC, Jim
hello ‘I write to you from Argentina and I want to arm the ardulaser, but can not find the wiring diagram or diode board or full codes, could help more specifically?
Unfortunately I don’t have that anymore 🙁 It was build a loooong time ago, and I lost the files somewhere along the way.
Hi Mark,
I tried to register with my callname IU3GMS, but something went wrong at mail server, so I can’t register again. please check the user db.
I am using your LibAPRS on a Genuino Mega and a SimpleSerial on a Nano, that are “talking” together succesfully (for the Mega I have changed the port definitions).
I made a little change on AFSK.h that has determined a very high percentage of success in decoding.
It seem strange, but this change consists on the inversion of mark and space frequencies.
As this articles says (http://owenduffy.net/blog/?p=2101), I saw a very high quality on 1200Hz note and a poor quality in 2200Hz.
the transmission started with 2200 tone, the receiver heard that frequency and than the frequency transitions.
Starting with 1200, the receiver decode and sincronize better.
Have you ever tried this?
Sorry for my english.
Best regards,
Luca
Hi Luca
That’s very interesting, thanks for sharing. I’m going to try that myself, and if I can reproduce the same improved performance, I’m going to implement that change. Thanks for the tip!
Hello, will there be some modems in stock soon?
Would love to get one.
mny73 DG0JUW
There will be more in stock in about 14 days 🙂
Hi there.
Just wondering if or when there will be another restock of the shop. I would love to get one from you.
73 DO2CHF
Hi! There will be stock again in November. I’ll make an even bigger batch this time, they always sell out way faster than I anticipate.
I am looking for 10 to 20 Bell 202 Dumb Modems for a special application in the alphanumeric paging service. The modem I have been using for the last 20 years is no longer in production.
My requirements are as follows: Dumb Modem (I have my own control signals). 300 to 1200 baud.
Standard Bell 202 tones.
In my application I use Audio in (FSK) Data out (Capable of Normal or Inverted polarity.
+12 Volts and Ground. 300 Baud Rate. And that is it.
Can You help me.
Thank You
I’ve sent you an email 🙂
Hey Mark,
please drop me a line when you are on stock again. Just wan’t to place an order of one or two modems and cases.
73, Silvio
Hi Silvio! Sorry for the slow response! There will be stock again in November. I’ll make an even bigger batch of everything this time, promised 🙂
I am using Code Blocks on a windows 8 computer, how do I get the micromodem source to compile? it can’t seem to find all the micromodem includes.
I’m sorry, but I don’t use Windows, and don’t know about Code Blocks. If you have avr-libc installed, that will be all the includes you need. Maybe you need to set up a path to the libraries in Code Blocks?
Hello. Can not register on the forum… 🙁
Hi Roma! Thanks for reporting that! I fixed the registration issue now!
Hello, I can’t register on the forum, so I ask here.
I just built the PTT and “soundcard” parts separately (first sending, second receiving data). I modified arduino APRS firmware (I left only raw data send and receive functions, I don’t need APRS at all, just AFSK code and a little AX25 code) and started testing!
sending part is Wouxun UVD1P, arduino nano 168 5v;
receiving part is Baofeng UV-5R, arduino pro mini 328 5v;
They are both on the table, 20cm between.
Everything work good, I’ve sent millis() and received in terminal. OK. but… may be 1 of 20 packets is lost.
I know it’s only ~5% of loss, but is it okay? (only 20cm between radios). I don’t have oscilloscope and my radioschematic knowledge is not perfect (as AVR programming, too), but if someone will direct me, will be good!
P.S. APRS arduino lib don’t have CSMA and error-correction, I will try to implement them. My goal is to implement simple mesh network with GPS location updates and encryption by key.
Please excuse me for my dirty english. Thanks!
Hi Roma!
I think 5% packet loss sound a bit high. Actually try moving the radios a little further apart, and if you are transmitting at higher power, make sure there is also at least 50cm between your modems and radios! If that does not change anything, I would increase the TX preamble a little and also make sure the input and output levels are well adjusted. This can be hard without an oscilloscope, but with a little trial and error, it should be possible to get it dialed in almost perfectly 🙂
Thank you, now it works perfect! My fault – wrong some of resistors rating.
Primero darle la enhorabuena por su proyecto y el exito que esta consiguiendo, solo queria saber si el MICROAPRS es un emisor de aprs, ya que lo que busco es un circuito que obtenga datos gps y conectarlo a un walkie y que este transmita la información a un receptor que ya tengo instalado. Gracias por su atencion y su buen trabajo
Hi Mark,
just wondering whether a new batch of micro modems will be available soon? (You mentioned November further up?)
tnx and best 73,
Peter, HB9TVK
Hi,
When MicroModem will be available again in stock?
NM
I am looking to purchase several Micromodems in the near term. Do you know when they will be back in stock and can be shipped to the US?
hello
here i can order the microaprs
best 73 !
Pedro Cruz
Hello Mark,
I am not able to reply to threads due to still missing confirmation from administrator.
Could you please acknowledge my request in the forum intruduction or delegate it to somebody?
Regards,
Pete, Germany
I just finished building your micromoden, but I can’t set the “PATH2-1 SSID to 1
I sent the modem “s21” this will not change the path, how do I change the path ssid?
WB$KDY
Hello Sir.
micromodem is out of stock.
do you expect restock?
Do you have more modems ? if you have that i will buy one for testing and if i can use it i will buy about 16 pieces of that !!!
best regards
Heino Jorgensen
de sm7mdo
Hello Heino!
I am all out of stock right now, but will have more in 2-3 weeks. Demand has been much higher than my production capacity for a while now, so I have been upgrading my workshop to be able to produce more units faster. I will start production of the new batches in 10 to 14 days, so if you can wait for it, they will be available again soon!
ok it good i will wait for it thank you
Hi!
I use your software midi katapult a lot for videosampling in Ableton Live. I would like to know if it is possible to make the launchpad mini (or the newer launchpads) compatible because the only one that work is the original launchpad. Is there a firmware sdk form novation that I could use? Thanks
Hi Markqvist,
I would like to order a pair of Micro Modems for an experiment. When will they be available? Also, can t he code be modified so it can be masked from the audio stream going to the transceiver? I intend to do that by using a very high cutoff HP filter, passing only frequencies above 400 HZ to the speaker amplifier. I don’t need high baud rate. I imagine the code is flexible enough to tailor the FSK frequencies.
Thanks,
Jerry Peck
Hi Mark, I was wondering: If you increase the number of DAC bits to 6 or 8 the signal out wuld be much better ?
Are these out of production now or just out of stock for a bit?
Dear Mark,
I have been working on making a micromodem. In the documentation, you write, “The git repo includes a prebuilt .hex firmware file you can upload to the modem.” Are these the four .hex files located in the “precompiled” directory?
Thanks for a very detailed and complete project. I am afraid my skills are not up to the level of writing my own changes to the software, BUT, I have really enjoyed pushing past my ignorance and learning WinAVR, avrdude, and learning what a bootloader is. I hope you haven’t abandoned this project yet.
Bruce
Been looking into building one for the fun of it. So far so good minus a few hiccups. I just have a few questions about the settings for the transmit delay and tail using the kiss protocol version. How can I set these? I noticed some general information saying it could be set in the kiss version, but nothing describing how. My plan is to use it with APRSDroid and Xastir on the computer. Xastir has settings for these but don’t seem to do anything. APRSDRoid does not have these settings.
Can the code be edited and compiled to accomplish this? Or some other method?
Hello,
I’m in the USA and been dyin’ to purchase a couple of the MicroModems..
How do I go about making a purchase?
Thanks,
Marc
Hi Marc,
They were out of stock for a while because I didn’t have time to make enough modems, but there’s more stock now, so you can just order however many you need!
Hi
Would it be possible witht eh micro modem to open a website?
i’m looking for something that can connect to phone line and when someone calls open a website
example.com/login.php?XXXXXXXX&YYYYYYYY
where XXXXXXXX is the phone number and YYYYYYYY is a password
Hi Bo
Something like that would be possible, but since MicroModem is primarily designed for radios, you would need to add a little extra circuitry to “pick up” the phone when someone rings. You’re welcome to send me an email with a bit more info on what you want to do, and I’ll try to guide you in the right direction!
Hello Mark,
What are the shipping costs for Europe / Italy, and what timing are there from the order?
Thank you
Hi Mimmo
There’s several shipping options to Italy. I’ll list them here below:
Untracked postal package: 5.5€, approximately 6 days.
Tracked and registered package: 18€, approximately 4 days.
GLS Europe: 29€, approximately 3 days.
I usually ship out orders on the same day I receive them, if I get the order before 14:00.
Let me know if there’s anything else you want to know!
Hi Mark,
I teach along the coast of Maine (USA) and would like to engage them in an electronics project. We have been playing with Arduinos and a couple have expressed interest in doing something like a High Altitude Balloon project, which I’ve done before with APRS beacons. Being on the coast, I’d like to try making a sounding buoy as well. These project ideas have something in common that hasn’t really been done much – an on-board “flight computer” which can transmit telemetry but can also receive commands. To do this, I’d like to use something like your MicroAPRS board – which I saw on your YouTube channel. It looks like something my students can “build from scratch”, which is important because I want them to feel like it’s their own project, and therefore something worthy of their time and attention. From your experience, would your MicroAPRS board work well? I have a radio for the remote unit and am starting to consider how the ground station should work, as I plan to use Processing to design a GUI for the ground station, to give it that “mission control” feel.
Thanks,
— Markus
Hi Markus
Sounds like a great project. I actually used to sell kits with PCB and through-hole components for building MicroModems, but I don’t carry those in the shop anymore. It’s still quite easy to assemble a working MicroModem on a breadboard or prototype board though, so it should be no problems. If you haven’t already found the schematics and such, they are all available on my Github page.
I think MicroModem would be a fine fit for the project. You could use the default firmware, or create a custom one using LibAPRS, depends on how you like to implement it really.
Sounds like a great idea with the Processing GUI! If it all comes together, please send me a few photos, would love to see how it turns out!
Kind regards, Mark
Outstanding! I have a question for you, since my tech knowledge is self-taught… I ask my friends about this and they say “oh yeah, a serial connection” like that explains the whole thing. And I’m sure it does – for them at least! So I’d like to ask what’s happening “under the covers” – feel free to direct me to resources you know of, they may have more information than what I’ve been able to find.
I see that, at least in the YouTube video, your MicroModem forms the “bridge” between the Arduino and the radio. While I can understand the serial data between the MicroModem and the Arduino, I’m still trying to wrap my head around the signals moving between the MicroModem and the radio. How is the MicroModem generating the sounds – the chirps that sound like a fax machine – that are transmitted to the radio?
Thanks,
— Markus
Hi Markus
Sorry, I had been very busy, and forgot to get back to your comment. The modem is internally synthesising the sounds in software. A loop is running 9600 times per second, and calculates the analog voltage level to output based on what audio frequency the modem should output. Then, this analog voltage is achieved in the real world by using a 4-bit DAC connected to four of the logic pins.
UPDATE:
I think the approach I’m going to take is to use two Arduino units. One will be the MicroModem to handle communications, the other will be the actual flight computer to receive commands and send telemetry. If I can make this work with off-the-shelf parts, I’ll probably look to make a specialized PCB design that incorporates both Arduino units. We’ll see!
— Markus
Yeah, it’ll probably easiest to start out with two separate Arduinos. That way you can just use the precompiled firmware on the modem Arduino, and have all your control code on the other one.
So… I just realized something from your comments. My goal is to give students a hands-on experience with technology. This is why your hardware approach is the perfect match for what I’m trying to do – it’s an Arduino (which a student could make from scratch if they wanted to) and the MicroModem that a student can solder for themselves. I’d really like that kind of experience for the software side as well. But I see in your comments that the MicroModem coding for the Microduino is a “black box” experience (precompiled firmware.) I know I’m asking a lot, but is there any way I could talk you into sharing your original Arduino IDE sketches? Or some “Microduino Light” sketches with basic APRS functionality? I’d like students to work with the actual files and upload them to the Arduino. This would help students see that rather than “waiting for someone to develop an app”, they can get in and make things happen themselves.
Thanks,
— Markus
Sure, all the source code for the MicroModem firmwares are available on my GitHub page already!
AX.25 firmware: https://github.com/markqvist/MicroAPRS
MicroModemGP: https://github.com/markqvist/MicroModemGP
I did not use the Arduino IDE environment for those firmwares though, as it is a bit limiting when you’re used to just using a plain old GCC toolchain.
But I absolutely understand the appeal of the Arduino IDE, so that’s why I wrote LibAPRS. It’s a library that can be added to the Arduino IDE, that contains all of the heavy-lifting code for modulation/demodulation, line coding, DAC output and so on. That way you can just code actual programs, and not worry about the really complicated stuff. Here’s info on the library: https://unsigned.io/projects/libaprs/
I think that will do what you want. The students can use a standard Arduino Uno or similar, and solder all the MicroModem components on a separate board, that can then be connected to the Arduino, and they can write code and upload to the completed modem from the Arduino IDE 🙂
Hello Mark,
since i am interested in the code of your micromodem (i own one), but i am not very skilled in
programming, i have a fundamental question:
Nearly all Atmega328-based modems (trackers) use one digital out pin for the AFSK.
I know, that this is done by performing a PWM with a sine table.
Why are you using 4 pins and how is it done ? Is the Atmega328 working as a kind of 4 Bit DAC ?
Is it possible to explain to me ? Normally my world is hardware – not software 🙂
best regards, 73 de dc1mak micha
Hi Micha!
Yes, the four pins are used as a 4-bit DAC, you are exactly right. It yields a higher quality signal than just using PWM on one pin. The modem is synthesising the correct frequencies for the AFSK signal in software, and translating to analog values through the 4-bit DAC at 9.6KHz sample rate. Hope that makes it more clear!
Kind regards,
Mark
Hi Mark,
absolutely clear now – thanks for you explanation.
Hi Mark,
Another question… I’m building the MicroModem from scratch. Rather than using a MicroDuino, I’m using an Arduino Mega, since it has the extra pins. Can you give me an exact list of what files (APRS.h, AX25.h, etc) will need to be included in my Arduino sketch? What is the syntax for sending and receiving a message coming from my radio?
Thanks,
— Markus
When will the next batch of Rnode be available to US customers?
I have components incoming, and will be restocked on november 14th the latest.
Hi Mark,
I have all the components and am starting to assemble them on a breadboard. I’m using ../ModemMicroduino/Modem.sch as the schematic. However I’m having some difficulty with the layout. There are places where the traces cross and they have a dot, indicating that the traces are connected – such as where R9 meets D3. However there are many other places where it’s not clear if the traces touch or not – such as R1, R2, R3, and R4 – there are two places where traces cross on their way to C1. Would it be possible to get an updated schematic that has a dot wherever the traces connect?
Thanks,
— Markus
Hi
I am SATYA, VE3YSN.
Can i use Micro modem as TNC to connect my FTM100DR ( Yaesu) , for packet communication, to use winlink, outpost etc.,
thanks and 73s
Satya
Hello Satya!
Yes, MicroModem works for this purpose! You will just need to make a cable to connect the DATA port of the FTM100DR to the audio port of the modem, and you are good to go.
Thanks Mark
Hi Mark,
Sorry to be a pain but I really want to get this up and running! I need some additional information regarding how to connect the MicroModem to the radio. I’m looking at the three connectors for the 2.5mm plug (sleeve, ring, tip) and the three connectors for the 3.5mm plug (sleeve, ring, tip.) I’m also looking at the schematic which has three “Radio” lead, one “PTT+” lead and one “PTT-” lead. Can you tell me what lead should be connected to what connector on each of the plugs?
Thanks,
— Markus
Hi Markus! No worries!
The pin options can be a little confusing, since it’s made to support as many different radio types as possible. I’ll explain it in general terms here, if you let me know what radio you use, I can probably provide more specific info.
The “AUDIO_IN” and “AUDIO_OUT” pins are pretty easy, AUDIO_IN is connected to the speaker/headphone output of your radio. AUDIO_OUT is connected to the microphone input of your radio. If your radio has a dedicated data port, use the in/out pins of that.
For the PTT part, there is a variety of options. There is one pin just labeled “PTT”. This is a 5V logic signal that is turned on when the modem requests PTT. So just before the modem starts transmitting, this pine goes from 0V to 5V, and stays at 5V during the entire transmission. Some radios have a “direct” PTT input like this (mostly mobile and base station radios, and almost anything with a dedicated modem or data port).
The other options is using the pin labeled “PTT_V+”. This option is mostly for use with handheld radios. Some radios supply a positive voltage on a pin of their headset connector, and when this pin is connected to ground, the radio will open the transmitter. Think of it as a simple push-button on a headset being pressed, and shorting the positive voltage to ground. The radio detects this, and opens the transmitter. As stated above, most handheld radios use this method. You just find what pin your radio supplies this voltage on, and connect it to the “PTT_V+” port of the modem. When the modem requests PTT, it will internally short the PTT_V+ port to ground, and the radio will open up the transmitter.
As a last resort, you can use the modem by using your radios VOX function, but I really don’t recommend it, since “real” PTT is much more stable and performs better.
I hope that helped! If you’re still having trouble, let me know!
Hi Mark,
Thanks for the info – very helpful to have that background! I’m tinkering with three radios – a Kenwood TH-D7, a Baofeng, and a Yaesu FT-2800m. I’m working off the schematic you have posted at http://unsigned.io/wp-content/uploads/2014/11/Schematic.pdf – specifically the pin-outs that seem to be related to the radio connections. I see a “Radio” block, containing pin-outs for “Line_Level_In”, “Mic_Level_Out”, and “Ground”. I see the “PTT+” block containing a pin-out for “PTT_V+”. I see the “PTT-” block containing a pin-out for “Ground”. I need to figure out how these connect to my plugs: 3.5 mm Sleeve, Ring, Tip and 2.5 mm Sleeve, Ring, Tip.
Thanks,
— Markus
Are you using a self-made modem, or one you bought from me? Since you are reffering to the schematic for the do-it-yourself version, I’m guessing it’s a self built one?
Yup – building it myself. The hope is to be able to do this with students so they can build the electronics more or less themselves so they can see that not everything is a “black box” and they can actually make things.
— Markus
Ah yes, that’s right, sorry couldn’t remember!
That’s right, the schematic you are looking at is the old “DIY” schematic, it is a bit simplified, and only has the pins “PTT+” and “PTT-“, not exactly like I described it in the above. You can add the logic level PTT signal like in the “full” MicroModem, by looking at the PTT schematic here: http://unsigned.io/wp-content/uploads/2014/12/Schematic.pdf
Since you’re going to be using a variety of different radios, I’d really suggest you familiarise yourself with how the PTT function works on the different types, then it’ll be easy to know how to hook things up for any radio. Also, a google image search for something like “[radio name] ptt pinout” will yield a lot of help in knowing what pins are what on various radios!
Hi Mark,
Thanks for the info! since I’m working with the “old DIY schematic”, I’d like to stick with that. (I have all the parts picked and installed on a breadboard at this point.) I’ve also been studying your YouTube video for this. (https://www.youtube.com/watch?v=L-LeizF6ixY&t=82s)
Basically, I feel like I understand the general schematic, but I’m having an “apples to oranges” moment trying to understand what part of your circuit connects to what plug going into the radio. If I focus on the Kenwood unit, I can see the schematic for the speaker and mic plugs. (http://manual.kenwood.com/files/TH-D7-English.pdf – see page 96).
I just need a list of what part of your circuit connects to what part of the plug (tip, ring, sleeve) for each of the two plugs (mic and speaker).
Thanks,
— Markus
Hi Mark,
Thanks for the info! since I’m working with the “old DIY schematic”, I’d like to stick with that. (I have all the parts picked and installed on a breadboard at this point.) I’ve also been studying your YouTube video for this. (https://www.youtube.com/watch?v=L-LeizF6ixY&t=82s)
Basically, I feel like I understand the general schematic, but I’m having an “apples to oranges” moment trying to understand what part of your circuit connects to what plug going into the radio. If I focus on the Kenwood unit, I can see the schematic for the speaker and mic plugs. (http://manual.kenwood.com/files/TH-D7-English.pdf – see page 96).
I just need a list of what part of your circuit connects to what part of the plug (tip, ring, sleeve) for each of the two plugs (mic and speaker).
Thanks,
— Markus
Hi Markus
I can understand that diagram on page 96 can be a little hard to decipher, if you’re not used to it 😉 Here’s a simplified connection diagram I found by googling “kenwood tnc pinout”: http://www.mfwright.com/KenwoodTHF6toKPC3.gif
That should make it absolutely clear what goest where. It’s the same way for 99% of all radios that use the Kenwood style connector. The PTT pin connects to the PTT_V+ pin on your modem.
Hi Mark,
Going tho. the tread, I want to be clear, before I place the order on Micro Modem
I use YAESU,FTM100DR, which has 10pin data port..
May I know , the connections diagram from PC – Modem – Radio..and want to use the Modem for Packet transmission AX.25
Thanks
Satya
Hi Satya
Look at the pinout here from the FTM100DR manual: https://unsigned.io/wp-content/uploads/2018/11/ftm100d_pinout.png
Connect MicroModem to PC via USB or direct serial port.
Connect PKD (pin 1) to AUDIO_OUT on MicroModem
Connect RX1200 (pin 5) to AUDIO_IN on MicroModem
Connect PSK (pin 3) to PTT on MicroModem
Connect GND (pin 2) to GND on MicroModem
Kind regards,
Mark
Hi Mark – apologies if this is a repeat – the website wasn’t posting my note so I sent it again.
Thanks for the info! since I’m working with the “old DIY schematic”, I’d like to stick with that. (I have all the parts picked and installed on a breadboard at this point.) I’ve also been studying your YouTube video for this. (https://www.youtube.com/watch?v=L-LeizF6ixY&t=82s)
Basically, I feel like I understand the general schematic, but I’m having an “apples to oranges” moment trying to understand what part of your circuit connects to what plug going into the radio. If I focus on the Kenwood unit, I can see the schematic for the speaker and mic plugs. (http://manual.kenwood.com/files/TH-D7-English.pdf – see page 96).
I just need a list of what part of your circuit connects to what part of the plug (tip, ring, sleeve) for each of the two plugs (mic and speaker).
Thanks,
— Markus
Hi Mark,
Thanks for the info! I’m just a little confused about the diagram you sent me. It has four leads (Mic, PTT, Spkr, Gnd) but your schematic has six leads (PTT V+, Gnd(1), Line Level In, Gnd(2), Line Level Out, Mic Level Out.) Can you tell me what connects to what? It’s a Kenwood radio, so can I assume:
3.5mm (Sleeve) PTT PTT V+
3.5mm (Ring) Mic Mic Level Out
2.5mm (Tip) Spkr Line Level In
2.5mm (Sleeve) Gnd Gnd(1) and Gnd(2)
Is that close?
— Markus
The blogging software took out some characters – let me try it this way:
3.5mm (Sleeve) PTT <> PTT V+
3.5mm (Ring) Mic <> Mic Level Out
2.5mm (Tip) Spkr <>Line Level In
2.5mm (Sleeve) Gnd <> Gnd(1) and Gnd(2)
Does this look like the correct way to connect these?
— Markus
Hi Markus
Yes, I’d say that looks good! By the way, it should be the same connection for those cheap Baofeng radios, if you use those as well.
Cheers,
Mark
when do we get the micro modem case?
Shall I wait to place an order for Micro modem, until you get the stocks for the case ?
I will have them in stock again in the beginning of January, so if you want the modem quick, you can order that now, and order the case later, or you can wait and order it all together.
Hi Mark,
I think I have the hardware all set for the MicroModem!
Now I’m moving on to the software. I see that you have some firmware files available. However because I eventually want to do this with students, I’d like them to use the Arduino IDE, since they’ll be using that for uploading other kinds of sketches to their Arduino. Therefore, can you tell me which files I’ll need and what sketch I need to upload to the Arduino to complete the process?
Thanks,
— Markus
Hi Markus
My suggestion would be to start off with one of the premade firmwares, just to test that the hardware is all working. The “SimpleSerial” version of the MicroAPRS firmware is very easy to communicate with over a serial console, it has a text driven interface with an interactive menu and help.
Once you know the hardware is OK, you can use LibAPRS (look in the “Software” section of my site) to easily program sketches in the Arduino IDE that can send and receive packets. LibAPRS takes care of all the heavy lifting of modulating, demodulating, packetising, checksumming and so on, and presents a simple API to send and receive data. There’s some included examples in the library to get you started.
Kind regards,
Mark
Hi Mark,
This sounds cool! I want to confirm though – the “SimpleSerial” version of the firmware, that’s something I need to flash to the Arduino using an ISP programmer, correct?
Thanks,
— Markus
Hi Markus
No, you don’t need an ISP programmer! Just upload it to the board over USB with the avrdude program. I personally find using avrdude easiest, especially on Mac and Linux, but if you’re on Windows and would rather like a GUI, there’s a free program called “XLoader” which you can use as well.
Hey Mark – Success! I still have a long way to go, but tonight I loaded the firmware and when I entered stuff into the serial monitor, it keyed the radio and transmitted! So I’m on the right path. Thank you for your patience – both over the past couple months and the questions still to come. Much appreciated!
— Markus
Hi from Istanbul, TA2IBT.
I’m a Search and Rescue member and responsible for communications. We need a communication module for teams comm. We can use PC-micromodem-radio combination for chat as youtube video : (https://www.youtube.com/watch?v=fWjoXkWOHYE).
We need something like a two way pager. We give pagers to our volunteers. Each pager has ID coded. In emergency situtation, we want to see where they are, are they active or passive for duty (they select) and communicate with all (send message to group). We maybe connect with phone (bluetooth) to send and receive messages.
– Send active APRS position
– Receive active APRS positions
– Send message
– Receive message
We need (I think) :
– Micromodem
– GPS
– Screen
– Bluetooth
– Battery
– Case
– Radio connection cable
– Keyboard (?)
APRS Screen Sample :
https://www.youtube.com/watch?v=HirYVgM6mMs
Is it possible to with micromodem? If it is possible, can you show way and true combinations. Thanks.
Burcak TURKAY
AKUT Search And Rescue Team
Hi Burcak
Thanks for contacting me! There’s several ways to do what you want, so I sent you an email at the address you specified here, so we can discuss the details!
Hi Mark,
If I may, a small piece of feedback from someone who doesn’t have an engineering background but is willing to tinker until everything goes right. I absolutely *love* that you have something people can build themselves from scratch. As you move on to new versions of your board, I would ask that you keep the “do it yourself” option up to date or even expand it. It would also be really handy if the schematics continue past what you currently have to include wiring all the way to the plug. (I understand you can’t do this for all radios, but I think if you did it for just one radio, people like me could use that and adapt it to whatever radio we’re using.) Now that I have a functioning breadboard – and all the notes I’ve made about the journey to get to this place – I’m looking forward to tinkering over the course of the winter!
Thank you again – for your resources, your patience, and your willingness to answer questions!
Regards,
— Markus
Hi Markus
Thanks very much for your comments and suggestions, I appreciate it. I agree that the DIY versions and resources should be kept more up-to-date. It’s something I’ve also wanted to do, but since I don’t really know how many people still use it, I’ve prioritised it further down a very long list of what I want to do. All of unsigned.io is basically a one-man operation, and unlike many others who just have a fab in China do all production, I actually produce all the hardware myself in my small workshop in Denmark. So between design, production, programming software and user support, it’s a constant balancing act of time. That being said, I will definitely try to get some time in to update the DIY instructions here in January or February.
Kind regards,
Mark
Outstanding! And happy to help in any way I can. (I’m a technical writer and educator – would be delighted to take on whatever would make your burden lighter.)
Happy New Year!
— Markus
Thanks a lot Markus, I will probably take you up on that! It would be a very great help! I am currently working on the final design of a new modem coming out soon, and after that, I will get in touch with you about this.
This sounds great – can’t wait to see the new modem! If I may… playing around with APRS stuff this week, I’m starting to understand about telemetry and how it’s displayed on APRS.fi. It would be super cool if you could include a couple sensor inputs in your new design.
— Markus
Here’s a little sneak preview of a prototype of the new modem I’m currently doing some testing on: https://unsigned.io/wp-content/uploads/2019/01/P1080689-e1548774569559.jpg
You’re not the first to request that, so there is now 4 user IO pins on the modem, that can be used as digital inputs or outputs, or analog inputs. There’s also free UART port that can communicate with whatever you’d like, and expansion ports for GPS and Bluetooth LE modules on board.
The PTT circuitry has been much improved, and four different PTT styles (should cover 99.9% of radios) are now selectable just by moving a jumper on the board.
Lot’s of software improvements as well. The modem is now both AX.25 and Ethernet compatible, and supports 300, 1200 and 2400 baud AFSK, selectable in software.
You’ll also notice there is now an SD card slot, useful for many things 🙂
Wow – this is a major upgrade in options and capabilities! Awesome!!
Wow!! Good stuff , thanks for sharing the info ..
Ok Mark – time for the next leap in my learning! I have implemented the serial firmware on the open source MicroModem, as we’ve discussed. Now I want to take the next step of building my own firmware. I’m guessing I need some libraries, but not sure what I need beyond APRSLibrary. I’ll see what I can put together, but suggestions and cautionary tales welcome!
— Markus
Hi Mark,
Question about the jumpers you use with your machine pins – I see it’s solid core wire with some kind of black collar around it. Just wondering what you use.
— Markus
Hi Markus, it’s something like these: https://www.sparkfun.com/products/11026
Hi Mark,
Another question – I’m using your file Basic_usage with the make-it-yourself modem. I ran the pre-compiled firmware and was able to make it work correctly. However the Basic_usage sketch is behaving oddly. I put in the necessary information (my callsign, destination callsign, etc.) and it will transmit a packet. However when it does so, the two LEDs both light dimly. The radio transmits for what seems like a long time. When it’s done transmitting, there is a very brief pause before it tries to transmit again. This doesn’t seem right. Is this something you’ve seen before?
Thanks,
— Markus
To add some detail – I’ve tried this with both a Baofeng and a Kenwood D-7 and I get the same response. If I run the sketch with no radio attached, one of the LEDs comes on which seems to correspond to a transmission. As soon as I connect the radio, it behaves as noted above. This is set with the ADC at 5v. When I change the ADC setting in Basic_usage to 3.3v, the behavior is different when connected to the radio. The LED I assume is the transmit light comes on fully (no dimming) at the same time the transmit light on the radio comes on. However it doesn’t key the radio. Not sure what’s going on here…
— Markus
Well OK! So now it’s behaving appropriately, I have no idea why. Something else I’ve noticed – the serial monitor only contains garbage characters. Will tinker with this more and see what happens.
— Markus
Well there it is! (Funny how posting on a board helps you find the answer sometimes!) I see the line: Serial.begin(115200) – so changed the serial monitor to 115200 and voila! 🙂
— Markus
Haha, yes, I know how it is. Glad you found it 🙂
Time for “Name That Function” in the “Basic_usage” file! There is a function called “processPacket()” called at the end of the file. I can’t find this function anywhere, even in Internet searches. Any idea what’s being called?
Thanks,
— Markus
The processPacket() function is defined in the Basic_usage file. Have a look here:
https://github.com/markqvist/LibAPRS/blob/master/examples/Basic_usage/Basic_usage.ino#L131
As the comments state just above the function definition: “Here’s a function to process incoming packets. Remember to call this function often, so you won’t miss any packets due to one already waiting to be processed”
As you can see in the code, the processPacket() function formats and prints out the received packet to the serial monitor. You might have noticed that there is also a aprs_msg_callback() function at the top of the file, that gets called when a packet has been decoded. So why not just print out stuff directly from this function? Why does the aprs_msg_callback() function simply copy the packet to another memory location, and set the “gotPacket” flag to true?
As you can read in the comments just above the function, the aprs_msg_callback() function will get called from within an interrupt. That interrupt needs to run 9600 times a second, so you only have about 0.1 milliseconds to execute code in each interrupt run. Printing out to the serial terminal takes a long time, so we need to execute that from the main program loop. That way the interrupt can, well interrupt, the slower running code, and everything will work. If the serial printing was being executed from within the interrupt code, demodulation and decoding would not be able to work while the packet was being printed out.
I highly encourage you to read through all the code in the Basic_usage example, and all the comments, a few times, from end to end. It should answer most questions 🙂
It would be awesome if we could work together at some point on improving the documentation for all of this, as you suggested. I’m primarily a programmer, not an educator, so while I try to make things as clear as possible in the documentation, it doesn’t always work 😉
Well I feel a little silly now… I did look through the whole file, and even used the search functionality. Not sure what was going on but thanks for the clarification! And yes, I’m up for helping out however it’s handy, particularly during the summer when school is out of session.
— Markus
A couple more questions about the “Basic_usage” file – neither of them about things that aren’t working:
1) On line 18, there are comments that start out, “You always need to include this function…” – can you talk a little more about what function this is referring to?
2) On lines 28 and 29, it talks about printing info, ending in “… from your main loop, like this:” – was there supposed to be something else there? The next line of code talks about setting the value for “gotPacket” but doesn’t deal with printing.
Apologies if this feels like I’m picking at small details, but I’m still learning how this all goes together and need to make sure I understand things correctly, though I’m sure this is one of those “everyone else gets it” items… 😉
— Markus
The comments starting on line 18 refers to the aprs_msg_callback() function. The aprs_msg_callback() is not called by the user, therefore you won’t find a reference to it inside the “Basic_usage.ino” file. Rather, the library itself calls back to this function when a packet has been decoded.
No, there was not supposed to be something else in there 😉 Try reading my previous comment again, and specifically the part starting with “So why not just print out stuff directly from this function?”.
As mentioned before the aprs_msg_callback() will get called from an interrupt. You can’t do anything that takes more than approximately 0.05 milliseconds inside the aprs_msg_function(). If you’re unsure exactly what I’m talking about when I say “interrupt”, try to read up on that topic. I know it’s a bit daunting when coming purely from the Arduino environment, which abstracts those things away, but you need at least a basic understanding of how an interrupt works, to understand why the code in the example is set up as it is.
To try and sketch it out, the aprs_msg_callback() function will not print anything out itself. It will just do two very simple things. One, copy the contents of the packet to a variable that the main program has access to, and two, it will set the variable gotPacket to true. That’s all.
Inside the programs main loop the processPacket() function is called. Inside the processPacket() function, there is a check to see whether gotPacket is set to true. If it is, the processPacket() function will print out the info.
If you can explain to me why we have to make this arrangement, you will have understood the code, I think 🙂
Hello!!! Do you have micro modem in stock right now ? (https://unsigned.io/product/micromodem-r23b/)
Hi there! Yes, there is plenty in stock for immediate shipping!
Okay , I’m working with Siwanan Poophat this is my project and i need to use this product immediately. So how long i get it. (Thailand)
Hi Surapat
With DHL Express shipping, it should not be more than 3-4 business days to Thailand. I ship daily, so you will have the products fast 🙂
Kind regards,
Mark