SPI clock issue not starting up properly on the NHS3100

[cpi-ugo]

See below image of the SPI lines on Salae showing the glitch I believe is causing round data into on the SI line. If I put a break point and step through the SPI transfer, the glitch won't be seen.

[patrickgeens]

Spoiler

Hi cpi-ugo,


Can you check if the clock frequencies restrictions are met?
In SPI controller mode, the maximum SSP bitrate is half the system clock frequency.

Info can be found in the SDK doc directory: "release_mra2_12_5_nhs3152/docs/firmware/a00860.html".

Kind regards,

Patrick

[cpi-ugo]

I have indeed checked all the documents (see below) but for some reason, I can't get stable communication if using any SPI clock bit rate more than 150KHz at Sys clock 4MHz. When I increased this to 8MHZ, I was able to push 400KHz on the SPI but with very unstable especially when starting up with only the battery connected, won't even connect via NFC with a weird noise played by the phone. 

I am left to limit the clock to 150KHz which is quite slow for my application.

[patrickgeens]

Hi cpi-ugo,

The weird noise from the phone when NFC tapping is typically an indication that there is no or a malformed NDEF message in the NFC memory of the tag.

For the instability problem I think we need to dive into the schematic, pcb/foil layout and prototype builds. Contact "nhs-support@nxp.com" for private support.

Kind regards,

Patrick

Kind regards,

Patrick