Comments on: Using SPI on an AVR (3) http://www.rocketnumbernine.com/2009/07/03/using-spi-on-an-avr-3/ Andrew's Project Blog - hardware, software, things Tue, 31 Aug 2010 07:51:52 +0100 http://wordpress.org/?v=2.9.2 hourly 1 By: Iggy http://www.rocketnumbernine.com/2009/07/03/using-spi-on-an-avr-3/comment-page-1/#comment-133 Iggy Tue, 06 Apr 2010 01:28:19 +0000 http://www.rocketnumbernine.com/?p=284#comment-133 This is terrific. With your three blog posts and the avr SPI library you posted @ google code I was able to get a nice dual avr setup w/ SPI between a 328 and a 644p. This is terrific. With your three blog posts and the avr SPI library you posted @ google code I was able to get a nice dual avr setup w/ SPI between a 328 and a 644p.

]]> By: andrew http://www.rocketnumbernine.com/2009/07/03/using-spi-on-an-avr-3/comment-page-1/#comment-72 andrew Wed, 09 Dec 2009 07:54:57 +0000 http://www.rocketnumbernine.com/?p=284#comment-72 If the controllers are on the same board or near I doubt if you need to add check sums - although it won't do any harm and would save you from the occasional sunspot In http://www.rocketnumbernine.com/2009/05/12/using-spi-on-an-avr-2/ I tested communicating with a chip that could send multiple bytes in one 'session' with no issues. If all the spi slave handler is doing is to save the bytes received in a buffer until all received there should be no problem as long as the SPI clock rate is not too high. Good luck Andrew If the controllers are on the same board or near I doubt if you need to add check sums – although it won’t do any harm and would save you from the occasional sunspot
In http://www.rocketnumbernine.com/2009/05/12/using-spi-on-an-avr-2/ I tested communicating with a chip that could send multiple bytes in one ’session’ with no issues.
If all the spi slave handler is doing is to save the bytes received in a buffer until all received there should be no problem as long as the SPI clock rate is not too high.
Good luck
Andrew

]]> By: Dale http://www.rocketnumbernine.com/2009/07/03/using-spi-on-an-avr-3/comment-page-1/#comment-71 Dale Wed, 09 Dec 2009 05:16:32 +0000 http://www.rocketnumbernine.com/?p=284#comment-71 Andrew, Thanks! I've been looking for an example of using SPI interrupt to handle receiving messages in an arduino slave. I'm concerned that if I just polled to look for new data available, would miss bytes. Would you have any advice on how long to make messages, whether it's required to do checksums on them? if doing a checksum on the message would you do that probably in the parsing of the message, not the handler which shifts into buffer. or would you add each byte as received, and have checksum already done at end. I have approximately 15 float variables to pass between controllers, is 60 bytes too much all at once? probably could/should reduce them to 2 byte variables instead. that's still 30 bytes. Andrew,
Thanks! I’ve been looking for an example of using SPI interrupt to handle receiving messages in an arduino slave. I’m concerned that if I just polled to look for new data available, would miss bytes.

Would you have any advice on how long to make messages, whether it’s required to do checksums on them? if doing a checksum on the message would you do that probably in the parsing of the message, not the handler which shifts into buffer. or would you add each byte as received, and have checksum already done at end.

I have approximately 15 float variables to pass between controllers, is 60 bytes too much all at once? probably could/should reduce them to 2 byte variables instead. that’s still 30 bytes.

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