Maximum spi transfer length

[DanisXZ]

Hi,

SDK - 17.1.0

I am performing an spi write of 500 bytes to an eeprom, but it does not seem to work if the TX length is above ~200 bytes.

nrfx_spim_xfer_desc_t xfer = NRFX_SPIM_XFER_TRX(tx_data, tx_length, reg_data, tx_length + reg_data_length);
err_code = nrfx_spim_xfer(&m_spim, &xfer, NULL);

Is there any limitation for the SPI max read/write length ?

[Håkon Alseth]

Hi,

 

EasyDMA for SPIM on nRF52832 is 8 bit (ie. up to 255 bytes):

https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52832.ps.v1.1/spim.html?cp=5_2_0_30_5_13#register.TXD.MAXCNT

You will have to split the transfer into multiples of 255, or consider using for instance nRF52833, which has 16 bits EasyDMA.

 

Kind regards,

Håkon

[DanisXZ]

Thanks