nrf52 gets stuck waiting for NRF_RADIO->EVENTS_READY?

[Andrew Kohlsmith]

I'm not using a softdevice, and am doing some time critical measurements when the radio begins transmitting.

This code works very well with nrf51:

__disable_irq();

NRF_RADIO->EVENTS_READY = 0;
NRF_RADIO->TASKS_TXEN = 1;

/* now spin, waiting for the radio to become ready */
 while (NRF_RADIO->EVENTS_READY == 0) ;

/* do something time-critical here */

__enable_irq();

On nRF52840, the while loop never exits.

Reading the nRF52 Seres Migration document v1.0.0, there is a section about the system bus write buffer (specifically regarding interrupt clearing) but my while does perform a read so the write buffer should be flushed. Nevertheless, I tried this as well:

__disable_irq();

NRF_RADIO->EVENTS_READY = 0;
 (void)NRF_RADIO->EVENTS_READY; /* flush write buffer on nRF52 */
 NRF_RADIO->TASKS_TXEN = 1;

/* now spin, waiting for the radio to become ready */
 while (NRF_RADIO->EVENTS_READY == 0) ;


/* do something time-critical here */

__enable_irq();

But this also hangs.

What am I doing incorrectly on nRF52?

[Quyen Dao]

I've just encountered the same issue, it turns out that I forgot to power on the RADIO.

NRF_RADIO->POWER   = (RADIO_POWER_POWER_Enabled << RADIO_POWER_POWER_Pos);

Hope this helps