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?

[Andrew Kohlsmith]

Just some updates (problem is still not solved):

• the radio state (0x550) is 0xc, which is TXDISABLED. I modified the while loop to continually issue TXEN and it still remains disabled.
• the radio config is 2Mbit, 5 byte address, 32 byte payload, 6 byte length, 0 byte S0/S1, with CRC, little endian and no whitening. Same as it was on nRF51 (same code in fact).
• HFCLK is running, and using external crystal
• This is on a Nordic 52840 400236 dev board, not custom hardware

A dump of the RADIO memory space when it is stuck waiting:

0000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
*
0000100 00000000 00000001 00000001 00000000 00000000 00000000 00000000 00000000
0000120 00000000 00000000 00000000 00000000 00000000 00000000 00000001 00000000
0000140 00000000 00000000 00000000 00000000 00000000 00000001 00000001 00000000
0000160 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
*
0000200 0000000b 00000000 00000000 00000000 00000000 00000000 00000000 00000000
0000220 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
*
0000300 00000000 00000008 00000008 00000000 00000000 00000000 00000000 00000000
0000320 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
*
0000400 00000000 00000000 00000000 00000000 00000000 00000000 0000000a 00000000
0000420 0000000a 00000000 00000000 00000000 00000d01 00002040 00000000 00000000
0000440 00000000 00000000 00000001 00000000 00000000 00000000 00000000 00000000
0000460 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
*
0000500 00000000 20000ee0 00000050 00000000 00000001 00000006 00040020 00000000
0000520 deadbeef 50a0aa00 00000000 00000001 0000000e 00000003 00011021 00ffffff
0000540 00000000 00000000 00000000 007f0000 0000000c 00000040 00000000 00000103
0000560 00000000 00000000 00000000 00000480 00000000 00000000 00002800 00000000
0000580 00000000 0009160a 00003a08 0000011b 3e120b70 0004c300 00000000 00110020
00005a0 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
*
0000640 00000000 00000000 00000000 1c0f1508 00000200 00000000 00000000 00000000
0000660 000000a7 00000000 00000000 052d0000 00000000 000010fa 58782e03 0000033c
0000680 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
*
0000700 00000000 00000000 00000001 00000730 00000000 00000000 00000000 00000000
0000720 00000000 00006c08 00680000 0000a006 81008400 0000205a 00000000 00003090
0000740 00282320 0c8a0008 00000003 0a106106 05090511 01f4044c 00960177 02100304
0000760 66642120 78646464 006c6366 00000000 00000150 00000307 00000010 62040122
0000780 00000008 00000000 00000000 00000000 00000000 00000000 00000000 00000000
00007a0 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
*
0000800 ffffffff ffffffff 00000000 00000000 00000000 00000000 00000000 00000000
0000820 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
*
0000900 022722b8 00000000 00000000 00000000 ffffffff ffffffff ffffffff ffffffff
0000920 ffffffff ffffffff 00000000 00000000 00000000 00000000 00000000 00000000
0000940 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
*
0000c00 00000000 fffffffc fffffffc 00000000 00000000 00000000 00000000 00000000
0000c20 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
*
0000d40 00000000 00000000 00000000 00000003 00000002 00000000 00000000 00000000
0000d60 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
*
0000e00 00000000 00000000 00000000 00000000 00000000 00000000 00000003 00000000
0000e20 00000000 00000001 00000000 00000006 00000007 00000004 00000006 00000000
0000e40 00000000 00000001 00000002 00000014 00000006 00000000 00000001 0000000e
0000e60 00000001 00000003 00000003 00000001 00000001 00000001 00000000 00000002
0000e80 00000000 00000000 00000001 0000000a 0000000d 00000000 00000000 00000000
0000ea0 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
*
0000fe0 00000000 00000000 00000000 00000000 00000000 00000000 00000001 00000001

[ovrebekk]

Hi Andrew

In general the radio should be in the disabled state before issuing the TXEN task. 

Could you try to disable it first and see if it solves the issue?

NRF_RADIO->EVENTS_DISABLED = 0;
NRF_RADIO->TASKS_DISABLE = 1;
while(NRF_RADIO->EVENTS_DISABLED == 0);

Best regards
Torbjørn

[lbe]

Hello,

I use this existing thread because I am actually experiencing the same problem on the NRF52832 dev board.

I am implementing a custom radio protocol, and the radio hangs in the  activation loop.

Furthermore, sometimes when in debugging mode, I got an Hardfault (I don't know if this is related to the debug mode though).

I tried the proposed solution with the radio disable, but it does not solve the issue.

Thanks for your help,

Lorenzo

[ovrebekk]

Hi Lorenzo

If the fix proposed here doesn't work it's probably a different issue. Could you please open a new item on this so we can handle it separately?

Feel free to mention my name, and the case will be assigned to me. 

If you can share your code in the case it will help. 

Also, feel free to share your motivation to implement the protocol from scratch, rather than using something like ESB or Gazell (needless to say, doing everything from scratch is a lot more time consuming). 

Best regards
Torbjørn

[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