Openmoko strives for openness

Ian Stirling OpenMoko at
Fri Apr 11 21:36:05 CEST 2008

Sorry for the delay in commenting, not been keeping up with the MLs.

Michael Shiloh wrote:
>  - Merge the debug board function on to the phone, perhaps with internal
> micro USB used for debricking and hacking.  No write-once memory.

>  - Discard U-Boot, minimal bootloader direct to kernel
>  - Focus on SD Card rootfs rather than internal memory
>  - Add a small lowpower MPU like TI MPS430 to manage everything
> seamlessly when main CPU is down.  Stuff like motion sensors, wake
> sources, battery management, maybe touchscreen, leds so there is an
> always-on "guiding hand" in the phone that is consistent and reliable

There are some MCUs that can help with several of these aims. For 
example - the STM32F103Tx - QFN36,  not too large, 32 bit, USB, 10K RAM, 
64K ROM, SPI with SD/MMC support, 10 A/D and $3ish in qty.

I'd envision this connected to JTAG on the SoC, with all the buttons and 
LEDs and the above connected to it, and connected in parallel with the 
USB outside port that would for example:

Battery insertion with button held down then USB plugged in:
    Act like existing debug board, do JTAG things, maybe even talk to SD 
card over SPI acting as a mass storage device.

USB plugged in - battery flat:
    Do host negotiation for more power, play tune or flash charging LED 
at user, flash to indicate how much we're charging, and if we can power up.
Normal condition - suspended:
    Talk to GSM modem over serial about stuff, poll accelerometers, 
maybe even listen to mic for user.

Are there any models completely lacking NAND flash, that are cheaper?

If the above was used, and was also connected to the SD, it could have a 
simple stupid 'read block 0 on the SD, and boot using JTAG' BIOS.

This could potentially delete the NOR flash, the NAND flash, and some of 
the glue.

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