Is putting +5V on the resonator pin of a 28X2 OK?

wapo54001

Senior Member
A 28X2 is operating on its internal resonator. During programming only, it would be convenient to apply +5V to a resonator pin (pin 10). Is there any problem with doing that other than it's unconventional?
 

fernando_g

Senior Member
Pin 10 is the resonator's amplifier output.
That particular output is a low power port and it actually operates class "A" (linear mode).

Unless that +5v source is high impedance, I would say it is not a good engineering practice.

Why would you want to do that?
 

oracacle

Senior Member
I suspect it is to make life easier to supply power to pin 20. its only reason I can think that any one would want to take power that way.
 

hippy

Technical Support
Staff member
Because the 28X2 supports a crystal or resonator, and leg 10 (OSC2) will be an output as that is the case; it would be something to be avoided.

One thing to bear in mind is that there is never any guaranteed 'only when programming' state of the PICAXE. When powered-up and after a program has been downloaded it will execute the program downloaded.
 

wapo54001

Senior Member
I can see that there are too many issues with doing a universal ZIF for programming as I originally wanted to do. So, I'm keeping the ZIF and the 08M2 to detect programming signal to turn on power to the chip to be programmed, but I'm adding three 4-way jumper sockets to accommodate the various Picaxe chips.

It turns out the wiring isn't that complicated and has the advantage of orienting pin one of every chip to pin 1 of the ZIF.

I'd upload a diagram, but the forum 'attachment' system doesn't seem to be working at the moment.
 
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