How to play with FreeCalypso GSM firmware on a Neo Freerunner
=============================================================

We have two entirely different firmware offerings for the Freerunner:

1. Leo2moko fw produced back in 2013-10: this is the only one suitable for
   end users.  We also have leo2moko-debug which is a slightly hacked-up
   version of leo2moko with some additional debug features for developers;
   this version is for developers only; end users should stick with the
   original leo2moko-r1 aka moko12 from 2013-10.

2. The work-in-progress full-source gcc-built FreeCalypso Citrine fw
   you are looking at can be built for multiple targets, and the
   gtamodem target is one of them - the original one, in fact.

The flash+SRAM chip which FIC/Openmoko populated in their modems provides
plenty enough RAM for the firmware's data space requirements, but not enough
to run a complete firmware code image entirely from RAM, hence whichever fw
version you would like to exercise, you need to flash it.  There are two ways
to flash modem firmware images in these smartphones: from inside the phone
(from the application processor) or externally through a special serial cable
inserted into the analog headset jack.  The internal method is intended only
for end users flashing released production-quality images; developers and
tinkerers are expected to use the serial cable method.

The serial cable wiring requirements for the GTA02 are the same as for Mot C1xx
phones, thus the same cable can be used for both.  The FreeCalypso project has
endorsed UberWaves as our official vendor for serial cables; George at
UberWaves now makes serial cables that are specifically certified for use with
FreeCalypso.  If you would like to order one, email uberwaves@gmail.com.

Please see the Current_Status write-up for the current status of the present
Citrine firmware.  As you can read there, this fw is currently nowhere near
being able to replace leo2moko.  Therefore, if you are going to flash Citrine
into your FR's modem, we expect that you are using your FR as a poor man's
substitute for the not-yet-built FCDEV3B (a board we seek to build specifically
for developers and not for end users), and are NOT expecting this experimental
work-in-progress modem fw to work together with user-oriented application
processor software like QtMoko or SHR.

If you would like to play with our experimental Citrine fw using a GTA02 modem
as the hw platform, here are the instructions:

1. Build the firmware in the gtamodem-gsm configuration - see the Compiling
   document for more details;

2. You should get a flashImage.bin image built; now you need to flash it into
   your FR's modem.  The serial cable method is highly recommended: the only
   thing you'll be able to do with our current not-fully-functional firmware is
   play with it and observe the debug output, and the serial cable will be
   needed for the latter part anyway.

3. Run fc-loadtool the same way you would if you were flashing leo2moko;

4. The actual flash programming commands are a little different because the
   image is smaller and in a different format:

flash erase 0 0x160000
flash program-bin 0 finlink/flashImage.bin

The second number in the flash erase command needs to be the size of
flashImage.bin rounded up to a multiple of 64 KiB (the flash sector size in the
GTA02 modem); 0x160000 is correct for the fw image size as of this writing, but
please double-check it yourself before flashing.  The 0 argument in the
flash program-bin command is the flash offset at which the image should be
programmed: it will always be 0 for FreeCalypso flashable fw images for gtamodem
and other targets that have the Calypso boot ROM enabled in the hardware.

Once you have flashed our experimental fw into your modem, you can power-cycle
the modem and see the new fw boot.  You should have the serial cable connected,
the serial channel enabled from the Freerunner's AP side and either rvtdump or
rvinterf running on your PC or other development machine when you first power
your modem up with the experimental fw in it: this way you will see the debug
output as the firmware boots up.

Once the firmware has booted, it needs to be controlled via AT commands.  The
present fw presents its AT command interface on two channels on this target: on
the MODEM UART going to the Freerunner's application processor and via RVTMUX.
At the present stage of development, we highly recommend that you avoid running
any GSM-driving software on the AP and exercise our work-in-progress fw solely
through the external serial interface on the headset jack, using rvinterf and
fc-shell.  The standard AT command interface on the dedicated MODEM UART is a
feature which we plan to address properly only when we build our planned FCDEV3B
hardware, which will bring both UARTs out to the external host.

Assuming that you already have rvinterf running in a terminal window (you should
have started it before you gave the modem power-on command from the AP side),
to exercise our firmware further, you will need to open another terminal window
on your driving PC/laptop and run fc-shell.  This program will connect to the
already running rvinterf process via a local socket, and it will enable you to
send various commands to the running fw on the target, the most important ones
being standard AT commands.  Send the following sequence of AT commands to
bring up GSM functionality:

AT+CMEE=2	-- enable verbose error responses
AT+CFUN=1	-- enable radio and SIM interfaces
AT+COPS=0	-- register to the default GSM network

To reflash your modem back to stable and working leo2moko aka moko12, execute
the following fc-loadtool commands:

flash erase 0 0x230000
flash program-m0 leo2moko.m0

(Whichever firmware image you are flashing, the flash erase command needs to
 cover the range of flash sectors this image will occupy.  You can erase more
 sectors up to 0x300000, the "natural" boundary of the flash area where fw
 images live, but I prefer to erase only the needed number of sectors: it is
 both faster and imposes less wear on the flash.)