nrf52 inv-ESB receive 0 length packets

[Liny]

hi,i have met some strange problem about inv-esb

i send 21 length packets in peripheral(i use rx as peripheral,use tx ascenter),but ireceive 0 length packets in center.

i printf the length of send packets in  tx-end-event of peripheral,such as this example:

it is in RADIO_IRQHandler():

if (NRF_RADIO->EVENTS_END && (NRF_RADIO->INTENSET & RADIO_INTENSET_END_Msk))

{

NRF_LOG_INFO("m_rx_payload_buffer = %d",m_rx_payload_buffer[0]);

}

and it printf "m_rx_payload_buffer  = 21".(this place i use uart to printf log)

but the problem is ,i printf length of receive packet,i get 0 results.such as this example：

it is in on_radio_disabled_tx_wait_for_ack（）

NRF_LOG_INFO("length = %d",m_rx_payload_buffer[0]);

and it printf "length = 0"

if i connect peripheral with jlink,and click "connect" in RTT-viewer,it won't happen,i can receive 21 length bytes.

i want to know why this happen ,and why i connect jlink with peripheral then it won't happen,thanks for your answer.

[Liny]

hi Hanon Alseth，

i have found the problem .

the reason is  when i send packets in periphral,  i add some code in on_radio_disabled_rx(), it takes more than 40 us （in radio fast mode，disable - tx raedy takes 40.25us ），it cause RADIO->PTR updated after tx-ready came。so ，although m_tx_payload_buffer[0] = 21, but NRF_PTR may not point m_tx_payload_buffer?(want your explain)。

i have a questions：

Q：does RADIO->PTR register  locked after tx—ready came？if not ，why？

[Håkon Alseth]

Hi,

 

You are changing the library, so I cannot state explicitly why its happening, but its usually two reasons:

1. Changing the content of the buffer after the radio has sent the data

2. Changing the PTR after the radio has latched.

 

You should not update the pointer after the radio has been started:

https://infocenter.nordicsemi.com/topic/ps_nrf52840/radio.html?cp=4_0_0_5_19_12#concept_dxt_xfj_4r

 

Once the START task is triggered, the EASYDMA latches, but note that the PTR register itself is double-buffered.

 

Kind regards,

Håkon

[Liny]

hi Hanon Alseth，

i have two questions:

1、can i modify the packet's length after tx—ready came but before event_address came?

2、can i modify the packet's payload  after tx—ready came but before event_address came?

added：in 52832

thanks！

[Håkon Alseth]

Hi,

 

You should not change the payload content after triggering TASKS_START. You should wait until the EVENTS_END is set to ensure that the content has been sent on-air.

 

Kind regards,

Håkon