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Picture of FCDEV3B board

We are proud to introduce our first FreeCalypso hardware product: a GSM mobile station development board. Our board features the same legendary TI Calypso GSM MS chipset that was used in commercial GSM/GPRS modems such as Openmoko's (our design is based on TI's Leonardo schematics and Openmoko's PCB layout), and functions as a standalone (or bare) GSM modem. The name of our board is FCDEV3B, which stands for FreeCalypso development board, triband.

Function and purpose

Before we can clearly communicate the purpose and function of our product, we first need to clarify what it is not:

So, if it is not any of the above, what is the function and purpose of our board? Answer: it is a platform for exercising, demonstrating and further developing our TI-based FreeCalypso modem solution. The primary mission of FreeCalypso is to give a second life (post-TI) to our beloved Calypso chipset+software solution, in order to fulfill the just-stated wish we needed a board that has the chipset on it and runs the software, and so we built our FCDEV3B.

When running our FreeCalypso Standard Modem firmware, the board functions as a standard AT modem, i.e., a standards-compliant GSM mobile station controlled via AT commands. To exercise our modem, you would need to get a SIM from your local GSM network operator, insert that SIM into the SIM socket on our board, power up and boot our board, then command our firmware to connect to the network, make and receive calls, send and receive SMS, exercise GPRS and other functions. It is a totally plain vanilla GSM+GPRS modem with an AT command interface, but with one very special feature: unlike our bigger competitors, we freely publish the complete source code for our internal firmware.

Hardware features


Compared to the mainstream commercial GSM modem kits for hobbyists and tinkerers and IoT/M2M applications and whatnot, our FreeCalypso GSM modem is unique in that it is explicitly designed to allow you to tinker with the inner workings of its firmware: you are explicitly encouraged to recompile our firmware from source and to flash your own fw builds into the modem, as well as to study our source, learn how it works, and make your own improvements which we never dreamt of. And if you totally dislike our firmware and wish to write your own completely from scratch instead, all hardware registers and functions are fully documented.

Compared to the ultra-cheap Motorola C1xx phones which are also based on the same Calypso chipset and which may thus seem no worse at first glance, our board is a fairly direct (by way of Openmoko) derivative of TI's Leonardo reference design, whereas Motorola's (really Compal's) hw design is considerably mutilated relative to the Leonardo baseline. Here are the serious shortcomings of Mot C1xx hardware:


If our product description sounds interesting to you and you would like to get one of our boards, how can one do so? The answer depends on your use case: