NRF 5340 spi4 communication, SDK 3.0.1

RE: NRF 5340 spi4 communication, SDK 3.0.1

Vidar Berg — Mon, 28 Jul 2025 06:50:27 GMT

Dear Minseok Kim,

[quote user="gwan0624"]However, even though I want to use 16-bit SPI, I found that using SPI_WORD_SET(8) instead of SPI_WORD_SET(16) seems to work without any problems. When I use two 8-bit buffers instead of one 16-bit buffer, it appears to generate a 16-bit clock signal.[/quote]

That explains it.The SPI HW does not support 16 bit operation so it will not work. However, spi_transceive() should have returned with -EINVAL with this word configuration: https://github.com/zephyrproject-rtos/zephyr/blob/6e3a1fda493a63806a315f56b57959ba57a2c9ba/drivers/spi/spi_nrfx_spim.c#L325

[quote user="gwan0624"]With SPI_WORD_SET(8) fixed, it seems that using a single 8-bit buffer generates an 8-bit clock signal, while using two 8-bit buffers generates a 16-bit clock signal. Is this the expected behavior?[/quote]

Yes, the 8 bit width does not limit how long a continuous transfer can be.

Best regards,

Vidar

RE: NRF 5340 spi4 communication, SDK 3.0.1

gwan0624 — Mon, 28 Jul 2025 00:07:13 GMT

Dear Vidar,

As you suggested, I tried setting the MISO pin to pull-up, but the issue persists.

However, even though I want to use 16-bit SPI, I found that using SPI_WORD_SET(8) instead of SPI_WORD_SET(16) seems to work without any problems. When I use two 8-bit buffers instead of one 16-bit buffer, it appears to generate a 16-bit clock signal.

With SPI_WORD_SET(8) fixed, it seems that using a single 8-bit buffer generates an 8-bit clock signal, while using two 8-bit buffers generates a 16-bit clock signal. Is this the expected behavior?

Best regards,

Minseok Kim

RE: NRF 5340 spi4 communication, SDK 3.0.1

Vidar Berg — Tue, 22 Jul 2025 06:53:20 GMT

Hello,

Please try enabling the internal pull up on MISO ( Unable to pull SPI MISO line down via device tree configuration ). This may help if the problem is that the slave is not driving the MISO signal after the CS has been asserted.

Bes regards,

Vidar