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Itsybitsy m4 express interfacing with ADS8638 chip via SPI.
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Itsybitsy m4 express interfacing with ADS8638 chip via SPI.

by suresh4693 on Sat Jul 11, 2020 3:21 am

Hello Team,

this issue continuation of https://e2e.ti.com/support/data-convert ... 3/t/893830
https://e2e.ti.com/support/data-convert ... 3/t/922061

-As per the itsybitsy m4express SPI MOSI- interfacing with ads8638 chip getting Spikes at the end of the 8-bit frame.
1. Is it a correct Senario or not .........?
2. If yes why?. As per SPI frame this is not right.
3. If this is correct Scenario..will the slave ADS8638 chip gets responded correctly?.
4, If this is wrong Scenario how to reove the spikes..

Thanks
Suresh.
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suresh4693
 
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Re: Itsybitsy m4 express interfacing with ADS8638 chip via S

by mckenney on Sat Jul 11, 2020 12:49 pm

It's not illegal. The master can do pretty much whatever it wants with MOSI as long as the clock is idle. It just must make sure MOSI is stable at the next clock edge (rising in this case). This is also true of the slave and MISO, but that's chancy since it doesn't know when the next clock is coming.

In this case, it appears that MOSI idles high, which is as good a choice as any.

[Edit: clarified wording slightly.]

mckenney
 
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