Tag Archives: GSM


Here is a quick update on the RasPiComm+ status. We are currently working hard on the Raspberry Pi drivers and hope to get the RasPiComm+ out there in Q3.

RasPiComm Plus

RasPiComm Plus mounted on Raspberry Pi with GSM and 16 isolated I/O extensions

The board itself is a 56x74mm 4-layer board, most components are mounted on the bottom. The top-side only features 4 edge-board connectors for the modules, power LEDs and two JTAG debugging/programming headers for the Cortex M3/M4F and the Altera MAX V CLPD.

We currently have 6 RasPiComm+ modules which we are testing:


CAN bus, RS-485, 8 inputs and 8 outputs RasPiComm+ extension boards

  • 8 Input (with adjustable reference voltage, can be jumpered to 5V or 24V or fed from outside)
  • 8 Outputs (5V or 24V or fed from outside)
  • GSM module
  • RS-485 (two RS-485 on one board)
  • CAN (two CAN bus ports on one board, you’ll need the ARM Cortex-M4 option to use both simultaneously)
  • 16 isolated I/O (using th iC Haus iC-JX)

The firmware of the Cortex M3/M4F (both can be populated) will provide a bridge from the extension boards to the Raspberry Pi and interface with the drivers. The ARM microcontroller can be programmed from the Raspberry Pi for power users. It will come with a fully functional firmware and does not need to be changed though. If you want do do realtime or high relieability stuff you can do this by programming the ARM microcontroller.

The CPLD is also programmable via the Raspberry Pi, so changing configurations for different extension modules is easy.

RasPiComm+ bottom side

RasPiComm+ bottom side

The big metal box on the bottom side is an isolated DC/DC converter. This will be optional and powers both the RasPiComm+ and the Raspberry Pi from a 24V power supply. The battery holder is for the real-time clock backup battery for which we will also add driver support, so that the Raspberry Pi can get the current date and time.

The driver is very elegant I think. You can dynamically load and unload driver modules and they create an interface (for example /dev/ttyRPC0) to the specified module in case the module is a serial module (this applies to the GSM, RS-485 and the CAN module). This is already working quite well, we successfully sent SMS messages from the Raspberry Pi.

For the I/O modules we are looking into a driver interface similar to the Raspberry Pi GPIOs, but this is still work in progress, if you have suggestions what the best way is to implement I/Os leave a message 🙂

I will post separate articles about the RPCP extension boards to explain them in detail.

And if you have any other ideas how to make the RasPiComm+ even better let me know!


Arduino/Netduino GSM Shield


Versatile Arduino/Netduino GSM shield

I needed a way to send SMS messages from a Netduino board, so I first tried the SM5100B shield. It worked somehow but it was not very stable and I did not like the hardware design. It also lacked some features. So I decided to build my own. Here is what I did (if you already used Arduino/Netduino the nomenclature below will be familiar, if not read a little bit about Arduino or Netduino, its a really nice microcontroller platform):

I wired both serial ports (so you can open a data connection and still send AT commands through the other line), A2 and A3 are used for ignition and hard reset of the gsm module and D12 and D13 are used for the ring indicator (signals events) and power indicator. These two lines are optional so I added an smd jumper pad which is connected and can be cut easily. the same is for the second serial interface.

I also added a battery holder for backing up the RTC in the module, so you do not lose the time stored in the module. Also very handy.
The SIM card holder is a push-lock and is on the bottom of the PCB facing to the side with the usb and power connector, so when a housing is used you can cut a slot into the housing and change the sim-card without opening it.

The USB port can be used to configure the GSM board, but this is optional. All settings can be made through the RS232 interface.

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