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Topic: Hardware SPI questions (Read 15 times) previous topic - next topic

Nick Gammon

Glad I could help. :)

According to some documentation I read, you could leave SS low (eg. tie it to ground at the peripheral end) and that would work with some devices but not others.

However some other devices (apparently) do not respond until they see the high-to-low transition. This makes a certain amount of sense, because otherwise a single glitch on the clock line could throw everything out by one bit, forever.

The act of pulling SS low effectively synchronizes sending and receiving, at least for those devices that look for such a transition.

Boffin1

Yes, I pull the shift registers latch low and high from the external circuit to latch it all in.
I should really do a notSCLR  between data I suppose to make sure it doesn't get out of sync?
With my mobile phone I can call people and talk to them -  how smart can you get ?

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