Werner Almesberger wrote: > Ian Stirling wrote: >> This would basically be a 'last chance, should never happen' event. >> >> It's in case someone intentionally unprotects and flashes the bootloader. >> >> (Intentionally, as it requires 2 specific 32 bit words written to the >> flash controller - which should not be present on the device, and be >> communicated to it by the 'flash' program.) > > Ah, now I see what you mean. If I understand things right, we may > not have to worry about this scenario: > > http://lists.openmoko.org/pipermail/hardware/2008-August/000307.html >
That works too. I went off on another tangent after this, and started thinking about something else, though I have not had time to flesh it out properly. Headset connector is quite sane and already exists. Well protected USB switches are available. http://www.maxim-ic.com/quick_view2.cfm/qv_pk/5233 Headset - USB plugs are widely available, used in the ipod shuffle for example. In normal headphone/headset operation, the switch simply connects L and R to the audio amp. When a USB->headset connector is detected, it switches to USB. When Vbatt = 0, and VheadsetIn = 5 (the state caused by the rest of the circuitry being unpowered, and the switch powered by VheadsetIn), it supplies a few mA to the STM, and then connects the rxd and txd of the STM to the serial bootloader. I was trying to elaborate this with another voltage, to allow the serial wire debug of the STM, when I realised I might be insane. This also potentially allows a much easier connector to 'dock' with. As I understand it, this would be compatible with headset wiring, but I haven't gone into this in detail. This does not answer the 'user does not have debug board' - but it reduces the nastiness of the 'dev board' - it's just a picked RS232-USB adaptor, a DB9 on a board, with a headset plug, and 4 or so passives, rather than having a FPN. Sorry for not fleshing this out properly before posting. _______________________________________________ hardware mailing list [email protected] http://lists.openmoko.org/mailman/listinfo/hardware
