nRF52 SDK11 SPIM example transmitting incorrect data

[bvuong87]

Hi All,

I'm using nrf52 PCA10040 v 0.9.0, with SDK11. No softdevice being used in this case.

While exploring using EasyDMA with the SPI peripheral, the example in sdk11\examples\peripheral\spi was mentioned here to get quickly started.

The example looks pretty straight forward, initializing a tx buffer with "Nordic" and looping forever sending it using nrf_drv_spi_transfer().

The project compiles and flashes, with no issue, and using Segger RTT I can see the "Transfer Complete" message everytime the transfer finishes. However, when taking a look at the actual SPI lines using a logic analyzer, the SPI data looks to be very incorrect. (See attached)

I notice an incorrect number of bytes being clocked out on each "transaction" (period where /CS is low) as well bytes which are not in the tx_buffer

Has anybody else seen anything like this or have any ideas on what this may be or what to look into?

Thanks!

[bvuong87]

Answered my own question again! The logic analyzer I'm using can only support SPI transfers up to 3MHz and the spi example configures the peripheral to run at 4MHz.

I changed the configuration to 1MHz and all is right in the world again :)