Individual port failures

[sbscott]

Can individual I/o ports fail/go bad but the picaxe can still be communicated with?

 

[inglewoodpete]

In my experience, PICs and PICAXEs are pretty tough chips. However, if a pin is damaged, usually with over-voltage, it is often difficult to determine if other damage has occurred to the silicon or not. You may find unexpected performance issues occur.

 

[sbscott]

I have a bunch of chips that I have collected over the years and thought I would test them to see if they still worked. Most did but, several, particularly the larger 40x1 are probably bad. I was able to load a simple port test program to turn on/off four ports. Three toggled but one did not. I am assuming that at least one port is bad on this chip?

 

[inglewoodpete]

I expect that all four ports are actually working OK. On the 40X1, Port D is an input-only port, so unlikely to even accept code to toggle the pins as outputs.

However, the PIC16F887 PIC that the 40X1 is built on has four bi-directional ports, so it may be possible to use the SFRs to turn these pins into outputs. I have not tried to do this, so you will be on your own if you want experiment.

 

[erco]

I haven't blown any Picaxe output pins but I have some BASIC Stamps with blown output pins which function fine otherwise. Amazingly a blown output pin can still function fine as an input. Per IWP, it likely depends on the nature and failure mechanism whether secondary damage is done to the silicon.