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Adjust SPI CS to CLK delay in MQX

Question asked by Sean Dowell on Oct 24, 2014
Latest reply on Nov 20, 2014 by Sean Dowell

I'm running MQX 4.1 on a Kinetis K60 and using CW 10.6 and I'm seeing a long delay on the SPI bus from when the chip select is pulled low to when the clock actually starts running. And then again when the clock stops till the chip select goes high. As you can see in the scope capture (SPI CS is 1 and CLK is 2) the clock (and data too) are pretty quick (around 1.5 us) but the whole time for the transaction is long due to CS being held low for so much longer (around 40 us). I'm using a protocol that does lots of short 1 byte transfers and this 40us starts to add up even though the data is actually sent pretty fast.

 

I can't figure out how to control this time in MQX. Does anyone know how to adjust these delays under MQX?

 

Thanks,

Sean

 

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