EIP B40 anybus embedded module - I have a question about SPI clock rates and CRC errors. We had our clock rate for the SPI bus set to 12.5 MHz and that worked great - but our computer board turbos and causes that SPI clock rate to 20 Mhz on the SPI clock. During that time we went from no errors in our SPI communication to an almost unusable amount of CRC errors and retries when it was up at 20 Mhz. Our clock and data signals looked crisp. Does this make sense to you ? At what speed would you say you would stay safely below to avoid this? We are obviously bumping into a hard limit.
Without having more information on this, it’s a little difficult to say what the issue might be. Is there any chance that you have a Saleae Logic analyzer so we could see the errors that are happening on this device?
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No I do not. The CRC errors were determined by the software programmer. He must have been looking at anybus status register. When the unit was running at 12.5MHz all was good and no errors. When the CPU clocked up the SPI clock to 20Mhz he started getting errors. He slowed it completely down to 1 Mhz and we do not see errors now. I would rather not run at 1 Mhz. so I was looking for guidance. If you say 20Mhz should be fine then we will relook at it. He did not know the CPU was speeding up the SPI clock. He only noticed the errors. So his instinct was to slow it down. That worked.
Our devices should be able to support a 20MHz clock based off what I’m seeing in the host application implementation guide:
But as for what’s causing these issues right now it’s a little hard to say without more info
Ok thanks, that’s what I needed to hear. I will dig deeper and see if I can get more info.