Hello FreeCalypso community, I have an announcement to make: I am looking into building a new GSM MS development board, tentatively named FC Minnie. (This choice of name was inspired by this board being a "mini-modem".) FC Minnie will be built around FC Tango module (previously known as iWOW TR-800) in very much the same way how the proposed Sysmocom board of OS#4030 is designed around Huawei GTM900-B module, and is intended to compete for the same market niche as that supposedly-coming-soon OS#4030 board. It may be worth noting that the module that now lives as FC Tango was already a direct competitor to Huawei GTM900 back in mid-2000s, back when it was called iWOW TR-800, obviously long before I entered the picture - but it was so obscure that I only discovered its existence at the very end of 2019.
The design of FC Minnie will be different in one significant way from all previous FC boards - I aim to make it as low-cost as possible, within the constraint that it must still support standard FreeCalypso workflows that have already been established with FCDEV3B and Caramel2. One key point that needs to be borne in mind is that hw requirements imposed by FreeCalypso and OsmocomBB projects are asymmetric: every board that is designed for FC can also trivially run OBB, but not the other way around. As it currently stands, the board design contained in the gtm900-breakout directory of osmo-small-hardware git repo and discussed in OS#4030 is very unfriendly to working not only with FC, but even with Huawei's original official fw - it is essentially an OBB-only board. The dates on the files in git and on the Redmine ticket make it look like an abandoned project, but I've been told that this project is still active and may be reaching the public hacker community by way of Sysmocom webshop "some time soon". Seeing an OBB-only hardware offering reach general public availability, presumably at a fairly low cost, while the nearest FC-capable hw options are more expensive and have no easy distribution channel, constitutes an *intolerable* injury to my pride, and therefore I MUST do everything humanly possible to correct this situation. FC Minnie is going to be my current attempt at a solution. My intent for FC Minnie is to make a proper superset (in the strict mathematical definition of this term) of the capabilities of OS#4030 board. If someone wishes to run OsmocomBB on an FC Minnie board (despite having been very clearly warned that doing so outside of a Faraday cage is a very bad idea), they can easily do so - board support for target tr800 has already been merged into osmocom-bb master, from a patch which I submitted properly via Gerrit this time around. But the board will ship with FC firmware already in flash, so if you simply turn it on, you will get an AT command interface on ttyUSB0 and an RVTMUX binary packet interface that works with rvinterf tools on ttyUSB1. Cost reduction - I will be making the following two big changes from Caramel2+DUART28 duo to FC Minnie with the aim of reducing cost: * The modular dual-UART interface will be eliminated - FC Minnie will be just one board, hosting both the GSM domain (Tango module) and the USB domain (FT2232H to two UART channels). This combination feels philosophically wrong, having a modular interface between these two realms (and separate power domains) feels more right - but the modular interface adds cost. It costs more to produce two custom boards than one, connectors and cables are extra BOM parts, and the interdomain interface with LVC buffers can be simplified a little when both sides are fixed. * FC Tango (formerly iWOW TR-800) brings out a lot of interesting interfaces on its 80-pin connector: full Calypso memory bus for hooking up extra parallel peripherals, I2C, keypad lines, battery charging, two ADC channels, you name it. (GTM900 is bare minimum in comparison.) iWOW's original development board (DSK aka Caramel) brings out most of these signals on a big 56-pin header, and so does FC Caramel2. But this provision once again adds cost: there is the BOM cost of the 56-pin header itself, plus the PCB needs to be bigger and thus more expensive. This expansion interface will be eliminated on FC Minnie, leaving only a 5-pin header for MCSI (digital voice channel) like on FCDEV3B. A fully modular version (two boards instead of one) with the Tango-based board bringing out all signals on the big expansion interface will still be available for those who need such and would be willing to pay a little more - but FC Minnie needs to be very aggressively cost-reduced in order to compete with the board of OS#4030. I will be designing this new board in my ueda hardware design language (functional equivalent of schematics, but textual instead of graphical drawings) and then handing it over to one of my trusted contractors for PCB layout, probably the same gentleman who did the PCB layout of DUART28 and Caramel2, if he will be available when needed. (I have worked with 3 different PCB layout contractors over the years so far, all 3 very good.) It will take me a little while to create the design at schematic-equivalent level (which includes nailing down every part on the BOM and specifying the exact PCB footprint for it) before I can hand it over to layout, thus the time between now and the layout hand-off is the time window when I can receive suggestions from the community and possibly incorporate them into the design. The design will be done in one of my public Mercurial repositories, I will start by writing a detailed board design specification, and that spec will be posted for review once it's ready in its first draft. Hasta la Victoria, Siempre, Mychaela aka The Mother P.S. I originally planned to post this announcement to both FC and OBB mailing lists, and wrote it with that intent, but then I changed my mind - for the purpose of informing the people who matter the most, posting just on the FC mailing list should be sufficient. However, if anyone feels that this announcement should be posted to OBB ML as well, please feel free to repost it there. _______________________________________________ Community mailing list Community@freecalypso.org https://www.freecalypso.org/mailman/listinfo/community