SPI read failure after upgrading from NCS 3.2.4 to 3.4.0 on nRF52840 custom board

[Yoshihiro Goto]

Hi,

I am experiencing an issue where SPI read operations fail after upgrading from NCS 3.2.4 to NCS 3.4.0.

Hardware:

• Custom board based on nRF52840
• ADS1294 (ECG ADC IC) connected via SPI
• The board has a proven track record working with nRF5 SDK and NCS 3.2.4, so hardware issues are ruled out

Symptoms:

• SPI read works correctly on NCS 3.2.4
• After upgrading to NCS 3.4.0, SPI read always returns 0xFF, suggesting that MISO is not being driven and the SPI read itself is not functioning

What I have tried:

• Added spi-cs-setup-delay-ns and spi-cs-hold-delay-ns to the SPI device child node as per Zephyr 4.3.0 migration guide → no improvement

Questions:

• Are there any breaking changes in NCS 3.4.0 / Zephyr 4.3.0 related to SPI that I might be missing?
• Is there any additional configuration required for SPI on NCS 3.4.0?

Any help would be greatly appreciated.

Thank you.