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Are there any dedicated Propeller pins aside from power, ground, xtal one shoul — Parallax Forums

Are there any dedicated Propeller pins aside from power, ground, xtal one shoul

HarleyHarley Posts: 997
edited 2006-07-14 05:43 in Propeller 1
Searching the Propeller manual for dedicated pins, found none.

But seems I've read 'something/somewhere' to look at the Propeller Demo Board how the I/Os are used. If one is attempting to set up a protoboard (those using solderless connections, it appears that:
P0 - P7 is free
RESn is part of the serial I/O i/f
P8 and P9 is mic input (analog input)
P10 and P11 is stereo audio output
P12 - P15 is for TV (monitor or actual TV) video and audio
P16 - P21 for VGA drive
P24 and P25 for PS/2 mouse
P26 and P27 for PS/2 keyboard
P28 and P29 for EEPROM i/f
P30 and P31 serial I/O.

I assume the reason to retain these pins is to run demos without modification if one wishes to run the demos on the PropSTICK; is this correct? Or are there other reasons; like is there any dedicated h/w for serial I/O P30 and 31?

If this is called out in the manual, what's the real word(s) I should be searching for? A 400+ page manual isn't trivial for use in starting out with this neat IC. tongue.gif

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Harley Shanko
h.a.s. designn

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2006-07-14 03:41
    Pins 28 through 31 are dedicated during the boot process with 30 and 31 used to talk to a PC if present and 28 and 29 used to talk to an EEPROM if present. Once the boot process is over, these pins are available for general use. On the demo board and some other proto boards discussed on this forum, these 4 pins are not made generally available. On the PropStick, all the pins are accessible, but pins 28 and 29 are still tied to the EEPROM and have pullups to 3.3V. I believe pins 30 and 31 are left connected to the RS232 level converter. The transmit pin is usable, but the receive pin is driven by the converter and not really useful for anything else.

    If you're making a production Propellor board and don't need to download new software, you can use pins 30 and 31 for something else (as long as it doesn't conflict with the boot process). You're probably going to use pins 28 and 29 for a general I2C bus since it's used during boot for that purpose. You can always hang a real time clock, extra memory, etc. off those pins.
  • HarleyHarley Posts: 997
    edited 2006-07-14 05:43
    Mike Green said...

    Pins 28 through 31 are dedicated during the boot process with 30 and 31 used to talk to a PC if present and 28 and 29 used to talk to an EEPROM if present. Once the boot process is over, these pins are available for general use. On the demo board and some other proto boards discussed on this forum, these 4 pins are not made generally available. On the PropStick, all the pins are accessible, but pins 28 and 29 are still tied to the EEPROM and have pullups to 3.3V. I believe pins 30 and 31 are left connected to the RS232 level converter. The transmit pin is usable, but the receive pin is driven by the converter and not really useful for anything else.

    If you're making a production Propellor board and don't need to download new software, you can use pins 30 and 31 for something else (as long as it doesn't conflict with the boot process). You're probably going to use pins 28 and 29 for a general I2C bus since it's used during boot for that purpose. You can always hang a real time clock, extra memory, etc. off those pins.

    Thanks for the guidance for my protoboard setup. No, not for production, just for learning this new micro, language, and possibilities the Propeller can provide. Just trying to 'plan ahead' for the solderless breadboards I received today from All Electronics. smurf.gif

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    Harley Shanko
    h.a.s. designn
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