RADIO Power Control for Register reset

[jake.yoon]

Hello, I'm working on timeslot and RADIO on nRF52840.

I found a sample code which sets 1 to "NRF_RADIO->POWER" to initialize RADIO peripheral.

-------------------------------------------------
/* Reset all states in the radio peripheral */
NRF_RADIO->POWER = 1;
-------------------------------------------------

However, the description in "6.20.14.39 POWER" is somewhat different.

-------------------------------------------------
Peripheral power control. The peripheral and its registers will be reset to its initial state by switching the peripheral off and then back on again.
-------------------------------------------------

It is clearly saying that the POWER should be set to "0' and then "1" like following, isn't it?

-------------------------------------------------
/* Reset all states in the radio peripheral */
NRF_RADIO->POWER = 0;
NRF_RADIO->POWER = 1;
-------------------------------------------------

[Håkon Alseth]

Hi,

 

The PS register definition should help you:

https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52832.ps.v1.1/radio.html?cp=4_2_0_22_13_45#register.POWER

 

.POWER=0 means that the peripheral is powered off. .POWER=1 means that power is routed to the peripheral, and you can start configuring and using it.

 

Kind regards,

Håkon

[jake.yoon]

Of course, I know what .POWER=0 and .POWER=1 means.

And to set .POWER=1 when it was .POWER=0 means that the RADIO is turning on and all the register values will be their default values.

What I'm asking is that "to set .POWER=1 when it was already .POWER=1 makes the registers to their default value. Is it?

[Håkon Alseth]

Hi,

 

jake.yoon said:

What I'm asking is that "to set .POWER=1 when it was already .POWER=1 makes the registers to their default value. Is it?

My apologies for misinterpreting.

Only toggling the power, ie. at some point setting the .POWER=0, will reset the registers.

 

By the way, since you're writing to a peripheral mapped register, you should introduce a wait-condition, as its not running on the same clock speed as the CPU:

NRF_RADIO->POWER = 0;
/* Dummy read of random volatile register. Wait state to ensure write */
(void)NRF_RADIO->EVENTS_DISABLED;
NRF_RADIO->POWER = 1;

 

Kind regards,

Håkon

[Dmitry]

jake.yoon said:

What I'm asking is that "to set .POWER=1 when it was already .POWER=1 makes the registers to their default value. Is it?

No, you should set it to 0 then 1.

[jake.yoon]

Thank you for the kind and clear answer.

[jake.yoon]

Thank you for the answer.

You have even answered to my next question for the time of turning on/off.

1. By the way, is the register readable even when power is down?

2. Is the register reading blocking action? (ie. line 3 "(void)NRF_RADIO->EVENTS_DISABLED;" is waiting until power is completely down/up?)

3. Then, is following the proper way to start RADIO operation in timeslot?

NRF_RADIO->POWER = 0;

/* Dummy read of random volatile register. Wait state to ensure write */
(void)NRF_RADIO->EVENTS_DISABLED;

NRF_RADIO->POWER = 1;

/* Dummy read of random volatile register. Wait state to ensure write */
(void)NRF_RADIO->EVENTS_DISABLED;

NRF_RADIO->TASKS_TXEN = 1;

 

[jake.yoon]

Dear Håkon Alseth,

Do you need more time to answer this question?

[Håkon Alseth]

Hi,

 

jake.yoon said:

1. By the way, is the register readable even when power is down?

Yes, the register is readable when .POWER=0.

To generate the wait state, you could read any EVENTS_* register, for instance (void)NRF_TIMERx->EVENTS_COMPARE[0];

 

jake.yoon said:

Is the register reading blocking action? (ie. line 3 "(void)NRF_RADIO->EVENTS_DISABLED;" is waiting until power is completely down/up?)

 Its ensuring a 16 MHz cycle wait is introduced, as all peripherals are running on the PCLK16M.

 

jake.yoon said:

Then, is following the proper way to start RADIO operation in timeslot?

Yes. Write .POWER=0, 1 cycle wait on 16M peripheral clock tree, write .POWER=1.

 

Kind regards,.

Håkon

[jake.yoon]

Thank you for the prompt answer.

I have one more question.

Do I have to reset the RADIO registers by myself whenever timeslot starts?

Or SD(Soft Device) resets them or powers down RADIO before calling my timeslot start routine(NRF_RADIO_CALLBACK_SIGNAL_TYPE_START)?

Best regards,

Jake

[jake.yoon]

Dear Håkon Alseth,

May I have the answer today?

I'm sorry for urging you but it's urgent to me(Of course, everyone here may say the same.)

Best regards,

Jake

[Håkon Alseth]

Hi,

 

jake.yoon said:

Do I have to reset the RADIO registers by myself whenever timeslot starts?

No, that should not be necessary. You only need to power it on.

jake.yoon said:

Or SD(Soft Device) resets them or powers down RADIO before calling my timeslot start routine(NRF_RADIO_CALLBACK_SIGNAL_TYPE_START)?

 The Softdevice will power off the RADIO peripheral after every connection interval is finished, to ensure it starts from a known position on the next connection interval it should handle. A timeslot is scheduled after a BLE operation is finished, so the timeslot will be opened up with .POWER=0.

For an example implementation, you can have a look at this blog post:

https://devzone.nordicsemi.com/nordic/nordic-blog/b/blog/posts/running-micro-esb-concurrently-with-ble

 

Kind regards,

Håkon