Let’s start playing with sigfox technology

SigFox with TD1208I already wrote some stuff about Sigfox here, so may know that it is a really promising French technology IoT oriented. So I have a project to connect a Raspberry Pi and arduino system on a such peripheral.  The use of this technology is quite easy as it works like a modem, based on AT command transfered over a 9600bps serial line.  The main issue is that the chip is really CMS and hard to hack at home easily… by the way, as you see, a poor soldering makes it working for the test purpose.

As much as I have test, I can say that using this device to communicate with an Arduino or a PI is really easy ! code can be written in less than a minute ; compared to what you have to do to make wifi / Ethernet / GSM working in a stable way, this is incredibly easier ! You can also use the device as an autonomous sensor for temperature and contact switch of your choice for an affordable price.  In my point of view one thing is missing : you do not really know the signal quality and if you have a good connection or not with sigfox network. [update] The RSSI is indicated in the SigFox Api on the backend side for each of the received messages [/update] . Meaning you must receive the first one to know if the location is covered or not. This can be a problem to deliver a product and get an easy support to your consumer. The other limit of the technology, as much as I know is that you can transmit data but not receive some from the SigFox network [update] The ability for the device to receive messages will be soon added with limitation, but it will [/update]. In many case it is enough but sometime you like to respond to a specific value received. Read next to get details on how to use it …

First step – Hardware stuff

The first step is to get the appropriate datasheet, this link is the right place to get the last one ! The schema to connect the TD1208 chip to the processor serial port is the following one :

TD1208 typical application

TD1208 typical application

RX signal is connected to TX on arduino or FDTI.

TX signal is connected to RX on Arduino or FDTI.

Personally I started to connect the TD1208 on a fdti cable to use it over USB on my Mac or my raspberry pi quickly.

Just have to be carefull, USB is delivering 5V power supply and this device is based on 3.3V.

Once connected, we just have to connect over the serial port and send some data !

Second step – Let’s make fun with AT cmd

Over a terminal session, it is possible to communicate with the chip. Basically typing AT will return OK. This is a good starting point. By default, device activate ECHO so you do not need to activate the local ECHO in the terminal.

Next try is to check versions : AT&V


Telecom Design TD1208
Hardware Version: 0F
Software Version: SOFT1198
S/N: 0000XXXX
E1 V1 Q0 X1 S200:0 S300:24 S301:2 S302:14 S303:1 S400:000000 S401:FFFFFFF S402:0 S403:869312500 S404:14


Third step – Let’s understand own to works

First thing to know is that this ship can be used for multiple usage :

  • The first one is named LAN and is a Local Area Network, it means that 2 (or more) TD1208 can communicate over the 868MHz channel with a speed of 9600bps.
    • In this mode you can have up to 15 devices and one of them is a gateway.
    • One TD1208 is a gateway, gateway basically echo the messages
    • The others are Devices that have to register to the Gateway
  • The second mode is SigFox, it allows a worldwide communication using the SigFox network.

The device can be configured as Gateway, Device or Transmitter ; this last mode is a standalone mode where the device is sending message over SigFox network. To get the device mode you can use ATS500? for example ; 02 means Transmitter.

The module includes some sensor, it can be automatically programmed to send alert of values measured on these sensors. This means it could be used as an autonomous circuit to monitor temperature for example.

The AT command to get these informations are

  • ATI26 : gives temperature in celcius (as much as i’ve seen it is not really precise)
  • ATI27 : return voltage in V

The At command list is accessible with AT? command

Fourth Step – Upgrade firmware

The firmware can be upgraded over the serial line. Unfortunately this can only be done on Windows … but I assume it is easy to revere engineer it ; things I’ll take a look later, as once you have deployed it on an embedded device you generally do not really want to move it to upgrade it … by the way just start the tool provided on the chip home page and the last firmware. Do not forget to choose the right chip and wait a short time. It’s done !

Fifth Step – Send the first message over SigFox

Sending a message on SigFox network is really easy : you just need to send the bytes over the AT interface :

AT$SS=00 01 02 03 04


This command has sent the 5 bytes {00,01,02,03,04} over the network. The message length is a maximum of 12 bytes.

sixth Step – Now receive the sent message

This part is the more complicated in fact as you have to registered the device in the TelecomDesign cloud or the SigFox backend.

Once registered (frankly speaking, you need to be a professional to register your device or going through an integrator/distributor), you have access to the SigFox backend, here you can follow all your sensors activity, message received, rssi :

sigfoxbackendTo proceed your message automatically on your own back-end, you can configure a Callback for a device. This callback is an url , owner by your application, that will be call each time a message is received. I’ll describe in a later article how to build an end-to-end example.

Next Step & next articles

One of the big advantages of this chip, as I said is that you can easily connect it to an Arduino or a raspberry Pi, but, instead of using an arduino, you can also build your own firmware and makes want you want based on the GPIO, I2C and ADC available on the chip. As the embedded arm core is more powerful than most of the arduino, it could be a good deal and allow to design really low cost sensors.

The chip is managing sleep mode and is based on low power component. As the transmission is really rare and short, the device life on battery should be really interesting to study.

The last point I need to clarify is how to get message from the SigFox cloud to the device, according to documentation is a capability of sigfox but reading the API, I do not see a lot of information 🙁






24 thoughts on “Let’s start playing with sigfox technology

  1. Thanks for the great post Paul! I just wanted to clarify that you do actually get the signal quality when SIGFOX sends you the message. The API documentation explains how to retrieve this, but ping me if you need help!


    • Well, it’s good to know 🙂 . I did not find it on the device side, the only RSSI monitoring seems to be applicable to the LAN mode only. I assume what you mention is the Sigfox API on the backend side.

  2. Very interesting post, I’ll try to make some nice projects with my arduino and raspberry with this technology, may I contact you if I encounter some issues ?

  3. Hi, Paul, thanks for all your posts about TD modem. I did some test for myself. As I live in a country without SigFox coverage (for the moment, hopefully ;-), I was trying only to compose LAN from two TD1208’s. I configured one of the modems to Gateway and one to the Device. Then I opened Gateway for registration by sending AT$LR=1 and tried to register the Device to the LAN by sending AT$LR to it. I always receive the ERROR response. Do you think it is even possible to compose LAN without Gateway registered to SigFox network? Or do I do some other mistake? Frequencies on both the modems are set to the same value.

  4. Great post!,
    But, at the end, is it possible to communicate from backend to device? What is the way to do it?

  5. Hi Paul,

    I am using a TD1204 as a TD1208 to send messsages on the Sigfox network. I write the AT commands with an Arduino Uno but I can’t find how to read the “OK” that returns the TD1204. Do you know if I can read those “OK” on the serial port with my arduino ?

    • sure you can …
      while ( Serial.available() > 0 );
      if ( Serial.read() == ‘O’ {
      while ( Serial.available() == 0 );
      if ( Serial.read() == ‘K’ ) {
      // Here you get the OK

      This solution is really bad as it is blocking but something like this make sense to get the OK. By-the-way, the ok just tells you that the transmission is finished, not more (when no downstream) so you can also just delay(8000); it will do the same.

      • Thank you for your help. But reading the “OK” is just a start. What I want to do is reading the GPS data. I know that if i use the command “AT$GPS=…” and put the parameters, the sigfox device can answer me by sending the GPS data to the serial port. So I think I asked you the wrong question before. I wanted to ask if I can read whatr the Sigfox is sending me on the Serial port with an arduino ?

      • You have to modify the code to consider any text string, but your question is clear : can your process the sigfox modem serial text with an arduino ? the answer is yes. Unfortunately you have now to create the right code to do it.

  6. Hi Paul,

    Your blog is really great. I have a question related to playing with Sigfox technology that I would really appreciate an answer to.

    How can one play with Sigfox in a city which has no Sigfox network available ? Can one obtain the parts required to build a 1-base station demo sigfox network just for running experiments?

    If I run your demo explained in this post, I will be able to send a Sigfox signal except there would be no network to receive it. Please advise.


    • Hello, Sigfox can rent you a base station, for this you can contact them. You can run my examples, it will work but you will never get the message until you have a basestation around.

  7. HI PAUL,




  8. Hi Paul,
    I am looking for the specification spectral mask for the RF transmission. Do you have that information?
    There is about 4 dB of peak to average ration in BPSK and because this is not a constant RF envelope, spectral regrow can rapidly spill into the adjacent channel.
    Thank you

    • Take a look to some of my post, you have some information about spectral but for details, you should directly ask to sigfox.

  9. Hi Paul,
    I have a Sigfox device (Mbili) and I put in commands in my serial monitor. The messages are getting retrieved in my Sigfox backend, though, I want my device to operate without any cables attached. (It’s now attached to my laptop.) I also want the data to be transmitted to a retriever. I am using a temperature sensor and I want the temperature to be transmitted so you can wirelessly transmit the temperatures.
    Thanks in advance

    • I assume your webserver called by the sigfox callback function is in your home network. Did you opened HTTP port on your internet gateway ?

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