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What is FreeCalypso?

The primary mission of our family of projects is to give a second life to a certain GSM baseband chipset+software solution that was once upon a time developed, then later abandoned, disowned and discarded in the trash by Texas Instruments (TI). Once upon a time, in a distant era long gone by, TI were in the business of making GSM (2G) and UMTS (3G) cellular baseband chipsets and the software that goes with them — but then they fully exited this business in 2009, and have since destroyed every trace of ever having been in it. All of the intellectual property associated with this business went into the trash dumpster — as we understand it, TI tried to sell that business unit, but failed to find an interested buyer.

However, some GSM cellphone and modem engineers who have worked extensively with TI's Calypso chipset have developed a deep love for this chipset and the software solution associated with it, and we are not willing to let it die. Therefore, we have taken it upon ourselves to give a second life to this chipset and its associated software post-TI. We buy TI-made Calypso and RF chips on the Chinese surplus market (they are still available in very large quantities despite having been out of production for many years), we design and build our own reference boards with these chips, and we strive to provide the same level of support for this chipset to the worldwide free and open source community as TI once provided to their customers.

What's in the name?

Calypso is originally a Greek mythology character, and it is also the informal but commonly used nickname of TI's GSM baseband processor chip formally known as HERCROM400G2. TI also made other GSM chipsets prior to exiting that line of business, most notably LoCosto, but the Mother who started the FreeCalypso family of projects has a strong personal liking specifically for the Calypso chipset (as opposed to LoCosto), hence the project name.

The Free part of our name refers to our use of the methods and principles taken from the world of free and open source software. It should be obvious that the historical Calypso chipset has no mainstream commercial value: it only supports the ancient GSM/2G technology with no possibility of ever supporting anything newer, and even for GSM/2G the newer chips made by MediaTek and Spreadtrum are much cheaper, more integrated and more powerful than the Calypso. Instead the only people for whom our TI-based FreeCalypso solution can possibly be of interest are free and open source enthusiasts and tinkerers, hence they are the audience for which our family of projects is targeted.

What makes the Calypso more free

From the viewpoint of the free and open source community, one major defect of all current (as opposed to historical) cellular baseband chipsets made and sold by companies like Qualcomm, MediaTek and Spreadtrum is that they are very closed: they don't provide detailed technical documentation for their chips, and the software (firmware) that is required for these chips to perform their useful function is available only as binaries without source code.

We don't know what TI's policies on such matters were back in the days when they were actively involved in this business — those days were before our time — but what practically matters in the present day, almost a full decade after TI's complete exit from that business, is that we were able to find many of TI's chip datasheets and other technical documents on Chinese mobile phone developer forum sites and elsewhere on the Internet, presumably posted there by various Chinese, Taiwanese and other Asian manufacturers of TI-based cellular phones and modems.

We have also been able to reconstruct the complete software suite for the Calypso chipset from the numerous fragmented bits and pieces which we have found on the Internet. The original bits and pieces which we found on the net were highly fragmented and incomplete, and it took the Mother several years of painstaking work to reconstruct the complete original solution in its full glory, but it has now been done: the software (firmware) that runs on our FCDEV3B modem board is built by us from source which we maintain — see our software page for more information.

We need donations!

Back in 2017 we have successfully produced our first FreeCalypso development board called FCDEV3B. These boards work quite well with the exception of just one defect: sleep modes don't work because the way we have wired the flash reset line (following TI's reference schematics) has turned out to not be correct for the high-capacity flash chip we are using. We now have a revised version of our board design that has this defect corrected, but we need money to make a new PCB fabrication and assembly run from the updated design files: we need about $5000 USD. Anyone who may be in a position to help, please email Mother Mychaela.