Pushing keys from KMU to ECB?

[SebastianA]

Hi!

I'm storing a key in the KMU for use by the ECB.

If I set the slot's destination address to an address in RAM, the KMU pushes the key there correctly, but if I instead set the destination address to &NRF_ECU00->KEY.VALUE[0], I can't push the key.

I run this code to push they key:

    if (nrf_kmu_status_get(NRF_KMU) != NRF_KMU_STATUS_READY) {
        printf("ERROR: KMU not ready\n");
        return;
    }
    nrf_kmu_keyslot_set(NRF_KMU, slot_id);

    nrf_kmu_event_clear(NRF_KMU, NRF_KMU_EVENT_KEYSLOT_PUSHED);
    nrf_kmu_task_trigger(NRF_KMU, NRF_KMU_TASK_PUSH_KEYSLOT);
    while (nrf_kmu_status_get(NRF_KMU) == NRF_KMU_STATUS_BUSY) {
        /* Busy wait */
    }

    if (!nrf_kmu_event_check(NRF_KMU, NRF_KMU_EVENT_KEYSLOT_PUSHED)) {
        printf("Failed to push key\n");
        return;
    }

I run this code in a mpsl timeslot handler.

I can write to the NRF_ECB00->KEY.VALUE[0] key registers there with the CPU.

Is there something more I have to do to be able to push they key directly to the ECB's KEY registers from the KMU?