How spi_xfer_done flag is being updated without calling its function in SPI example from SDK15.3.0 after the transfer?

[AimHigh]

Hi,

I could not find the logic for spi_xfer_done flag (main.c) that is being updated after SPI transfer is done in the SPI example from SDK 15.3.0.

There is no particular function call being made for spi_xfer_done flag to be updated.

Noticed that spi_xfer_done is updated after call to function below. (nrf_spim.h)

__STATIC_INLINE void nrf_spim_task_trigger(NRF_SPIM_Type * p_reg,
nrf_spim_task_t spim_task)
{
*((volatile uint32_t *)((uint8_t *)p_reg + (uint32_t)spim_task)) = 0x1UL;
}

I am dazed here, kindly help me understand this!

[Mojo]

Well, have you search for it in the main.c ? It is set in spi_event_handler.

[AimHigh]

Yes, i did. And you can see spi_evnt_handler is user defined and has only one call in nrf_spi_init function. And of course the flag spi_xfer_done is being update after nrf_spi_xfer function, to which spi_evnt_handler function is not passed as an argument.

[Mojo]

it is passed in the init function right ? The pointer is kept in the driver. So when transfer is done, it gets called. As simple as that.

[AimHigh]

You are right user defined event handler is called right after transfer is done. But it is hard to keep up with this API. Event handler is kept in m_hanlder[].