Andy Green wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Somebody in the thread at some point said: > | Werner Almesberger wrote: > |> Ian Stirling wrote: (of the stm32)
> |>> I think you can always mass-erase the chip though, so a USB bootloader > | If I read it correctly - you can secure the code - p22 of > | http://www.st.com/stonline/products/literature/pm/13259.pdf says you > | can't overwrite pages 0-3 in read-protected mode, without mass-erasing. > > We've been through this with the NOR. We really don't like write-once > stuff either for us having to make a golden implementation for the > factory or for the user not being able to update it in a package. If > malicious code mass erased this bootloader section we are bricked. > Fair enough. It occurs to me that another solution that isn't quite ideal might be possible. Make a 'debug board' available, but much, much cheaper. This would be something like (in basic form) A 20ish way 0.5mm FPC connector, replacing the existing debug connector, which - for most users - they simply connect with a basic debug board comprising only a 9 pin serial socket, a FPC connector, a couple of resistors and zener diodes, and a jumper. Plug the jumper in, you get bootloader mode on the STM. Don't plug the jumper in, and you get serial-console or something, from the STM32. Supply with a picked USB-serial adaptor that can live with 3.3V thresholds. This would solely be for recovering from a bricked STM32. The advanced debug board is either an existing one, with a converter board, or a new one. As a possible plus, this connector could also support add-ons, rather than the fragile expensive to make existing one. $5 for a serial-USB converter. $4 BOM, $1 PCB, $1 assembly (in moderate quantity) - plausible to sell at $20. (for production programming, I'd imagine a bed-of-nails, with power, ground and rs232 might be more convenient than the FPC.) _______________________________________________ hardware mailing list [email protected] http://lists.openmoko.org/mailman/listinfo/hardware
