Hello André, On Mon, Sep 29, 2008 at 11:50 PM, André Schwarz <[EMAIL PROTECTED]> wrote: > Leon, > > you're right. > PORESET is just there to prevent the core from running as long as power may > be unstable and/or PLLs are out of lock. > HRESET is the signal that should reset everything. I did it on my board and > it works fine. > Understood so far.
> Since you also have to assert HRESET when you assert PORESET > But when I assert PORESET, the processor will assert HRESET itself AFAIK, so why do this? > you can wire-or them with a low drop schottky diode. > Ooh, analog electronics, long time ago. Let me think: arrow of diode symbol pointing from HRESET# to PORESET#, right, so that PORESET# going low will pull HRESET# low enough, right? > Hope this helps. > Yes it does, thanks. Regards, Leon. > Leon Woestenberg wrote: >> >> Hello all, >> >> not Linux related per se*, but I wonder how your board designs deal >> with the reset circuitry for embedded PowerPC processors (MPC8313E in >> my case). >> My requirement is that both a processor-external hard reset and >> processor-internal hard reset must both reset the boot device NOR >> FlashROM, so that it does not remain in write mode (if it is). >> >> Given those processor pins: >> >> PORESET# (input pin to the processor, power on reset) >> HRESET# (bidirectional pin on the processor, asserted by processor on >> hard reset such as watchdog) >> >> I see many designs (even the Freescale reference designs) where the >> HRESET# resets some of the board, but not the FlashROM, and where >> PORESET# resets the FlashROM. This can cause a deadlock in the case >> where the watchdog resets during writing to FlashROM, as the FlashROM >> is not reset and remains in write mode, not allowing the processor to >> boot from it. >> >> I am thinking of using this approach: PORESET# -> processor <--> >> HRESET# -> board reset. >> >> Would that work? or why not? >> >> Regards, >> > > > MATRIX VISION GmbH, Talstraße 16, DE-71570 Oppenweiler - Registergericht: > Amtsgericht Stuttgart, HRB 271090 > Geschäftsführer: Gerhard Thullner, Werner Armingeon, Uwe Furtner > -- Leon _______________________________________________ Linuxppc-dev mailing list [email protected] https://ozlabs.org/mailman/listinfo/linuxppc-dev
