What is the safe way to implement ready line for SPI?

[neochinese]

I want to implement a ready line for SPI and I noticed nordic has similar code in your sdk: components/serialization/common/transport/ser_phy/ser_phy_spi_slave.c.

However the following comment concerns me: "     //toggle - this should go high - but toggle is unsafe"

So I want to do a safe version and I do the following change:

In spi_slave_gpiote_init(), I change the following line

>> nrf_drv_gpiote_out_config_t config = GPIOTE_CONFIG_OUT_TASK_TOGGLE(true);
to

>> nrf_drv_gpiote_out_config_t config = GPIOTE_CONFIG_OUT_TASK_HIGH;
>> config.init_state = NRF_GPIOTE_INITIAL_VALUE_HIGH;

And I also change the lines in set_ready_line()

from:

>> //toggle - this should go high - but toggle is unsafe
>> uint32_t rdy_task = nrf_drv_gpiote_out_task_addr_get(m_spi_slave_raw_config.pin_rdy)

>> *(uint32_t *)rdy_task = 1;

to

>> nrf_gpio_pin_clear(m_spi_slave_raw_config.pin_rdy);

But it doesn't work at all. The ready line keeps high and never becomes low which indicates ready. I don't know what I do wrongly and what is supposed to be the safe way instead of toggle?

[Edvin]

Hello,

This should not be set up like it is, as you say.

The reason that the nrf_gpio_pin_clear() does not work is that the pin is already "taken" by the task.

If you have set GPIOTE_CONFIG_OUT_TASK_HIGH, then you should use nrf_drv_gpiote_pit_task_addr_get() and *(uint32_t *)rdy_task  = 1; as it was. Have you tested that?

I have not set this up and tested it myself, but let me know if that doesn't work, and I will look into it.

Best regards,

Edvin

[neochinese]

I need to use gpio task so that my PPI can set the pin to HIGH when SPI transfer is done. Then I need to set the pin to LOW when my SPI slave is ready to receive. Then how should I achieve that? I can do it using toggle task but it doesn't seem to be safe.