nrfx_spim_xfer_desc_t: why both tx_lendth and rx_length fields?

[Daniel Reisfeld]

Hi,

The structure nrfx_spim_xfer_desc_t contains both tx_length and rx_length fields. 

Is there a situation where tx_length != rx_length ?

Thanks,

Daniel 

[ovrebekk]

Hi Daniel

Technically an SPI bus is always full-duplex, but very often you only care about the data flowing in one direction (when writing to displays or reading from sensors for instance). 

To avoid having to allocate RAM for TX or RX data that you don't care about it is possible to set the TX length shorter than the RX length and vice versa. 

Best regards
Torbjørn

 

[Daniel Reisfeld]

Torbjorn thanks! Daniel