A 2-Propeller 'reset' question

Harley

I have a 2-Prop board (a ProtoBoard with 2nd DIP40 Prop) and am wondering if there is 'any' problem with both RESn pins tied together???____

This board interfaces to another pcb with a 'reset' switch, which would be convenient to directly connect to that switch to the two Prop RESn pins without any other components. It seems to work OK connected to the other board, but am wondering if this creates any problems for PropPlug or programming an EEPROM.

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Harley Shanko
h.a.s. designn

Mike Green

You should be able to connect the two. If you're enabling the brown-out detector, if either Prop finds its Vdd too low, it will put both Propellers into reset. Both Props will come out of reset at about the same time and look at their P30/P31 lines for a download from a PC via a PropPlug. If that fails, they will both try to read from an attached EEPROM (on pins P28/P29). You didn't say how these Props are connected otherwise.

I suggest that the 2nd Prop have its own PropPlug header and its own EEPROM. You could connect the 2nd Propeller's EEPROM to another pair of pins on the "master" Prop and the "master" could write (and read) to it when the 2nd Prop is not accessing it.

Post Edited (Mike Green) : 3/8/2007 9:16:31 PM GMT

Harley

Thanks, Mike.

It seemed like there should be no problem with common reset. But wasn't sure if there were anything not considered.

At first I had each RESn separate, with resistors to 'protect' it from the 5v from the other board. (It is pulled up to 5v via a 10K resistor, so shouldn't be any problem, to my thinking.)

Yes, each Prop has their own EEPROM and programming header, and the BOEn's are grounded. No problem if one Prop resets the other.

Prop#1 outputs a 5 MHz squarewave for Prop#2's clock on X1. FSynth works great.

The reason for two Props is the interface required over 32 I/Os and 8 cogs; one used for TV_text for debugging (displaying internal 'register' use).

Thanks for the confirmation.

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Harley Shanko
h.a.s. designn