Zephyr SPI works in timer handler but not main functionhttps://devzone.nordicsemi.com/f/nordic-q-a/112271/zephyr-spi-works-in-timer-handler-but-not-main-functionI&#39;m having a problem using SPI within Zephyr. My custom nRF52840 board has 74HC959 shift registers to drive LEDs. I&#39;m using the SPI bus to transfer LED on/off states and can successfully do so when spi_write_dt is only called from a kernel timer handleren-USTelligent Community 13Thu, 20 Jun 2024 19:55:37 GMTRE: Zephyr SPI works in timer handler but not main functionhttps://devzone.nordicsemi.com/thread/489820?ContentTypeID=1Thu, 20 Jun 2024 19:55:37 GMT137ad170-7792-4731-bb38-c0d22fbe4515:056b4c04-76da-4b99-89c7-d0b6c2f9d4ddabhav<p>Turns out I overlooked the <code>count</code> field of <code>tx_spi_buf_set</code>. Even though the data to be written was len=2, the number of SPI buffer sets is only 1. Changing <code>count</code> to 1 fixed my issue. Really not sure why this even worked in the first place within the timer context, though it explains the error code I was getting.</p><div style="clear:both;"></div>