Dear all,
[nrf sdk version 17.02 ; Broad:nrf52840DK]
I am now combing the time sync code into ESB protocol.In the original time sync source code,time slot API is used in order to let esb work cocurrently with BLE protocol.
But in my case,I remove that part.I used esb_ptx to send data packet and using an app timer to trigger program sending sync packet each 30ms.
The method for taking timestamp to sync is one main difference from the source code shown below.
esb_ptx modification
typedef struct
{
uint8_t message_id; //recogonize sync_pkt or urllc_payload
} urllc_header;
//sync packet format
typedef struct
{
urllc_header header;
int32_t timer_val;
uint32_t counter_val;
} sync_pkt_t;
//data packet format
typedef struct
{
urllc_header header;
int32_t seq_num;
uint32_t time_stamp; //time stamp to evaluate latency
uint8_t data[URLLC_PAYLOAD_LENGTH];
} urllc_payload;
void take_sync_timer_val(sync_pkt_t* p_pkt)
{
uint32_t sync_timer_val;
uint32_t count_timer_val;
uint32_t peer_count;
timers_capture(&sync_timer_val, &count_timer_val, &peer_count);
p_pkt->counter_val = count_timer_val;
p_pkt->timer_val = sync_timer_val;
}
// timer handler for sending sync packet periodically
static void repeated_timer_handler(void * p_context)
{
tx_payload.length = sizeof(sync_pkt_t); //set packet length
tx_payload.noack = true; //sync packet is not required ack
sync_pkt_t *p_pkt;
p_pkt = (sync_pkt_t*)malloc(sizeof(sync_pkt_t));
p_pkt->header.message_id = SYNC_PKT; //rx used meassage id to tell whethere the packet is for sync or data transmit
take_sync_timer_val(p_pkt);
memcpy(tx_payload.data,p_pkt,sizeof(sync_pkt_t));
if (nrf_esb_write_payload(&tx_payload) == NRF_SUCCESS)
{
NRF_LOG_INFO("Sending sync packet succeed");
}
else
{
NRF_LOG_WARNING("Sending sync failed");
}
free(p_pkt);
}
In esb_prx,Rx will receive two types of packet,one is data packet with URLLC_DATA_PKT(0) as meassage_id,the other is sync packet with SYNC_PKT(1) as meassage
id.In RADIO_IRQHandler(),Rx first see the meassage_id,if it equals to SYNC_PKT,then the program follow the compensate procedure as the time sync code,I only modified the
Tx_CHAIN_DELAY to 2800.If Rx received the packet with URLLC_DATA_PKT as meassage_id,then the program follows the precedure in esb_rx.
esb_prx modification
void RADIO_IRQHandler() {
if (NRF_RADIO->EVENTS_READY && (NRF_RADIO->INTENSET & RADIO_INTENSET_READY_Msk)) {
NRF_RADIO->EVENTS_READY = 0;
//DEBUG_PIN_SET(DEBUGPIN1);
}
if (NRF_RADIO->EVENTS_END && (NRF_RADIO->INTENSET & RADIO_INTENSET_END_Msk)) {
NRF_RADIO->EVENTS_END = 0;
//DEBUG_PIN_SET(DEBUGPIN2);
// Call the correct on_radio_end function, depending on the current protocol state
if (on_radio_end) {
on_radio_end();
}
}
if (NRF_RADIO->EVENTS_DISABLED && (NRF_RADIO->INTENSET & RADIO_INTENSET_DISABLED_Msk)) {
NRF_RADIO->EVENTS_DISABLED = 0;
uint8_t message_id;
message_id = m_rx_payload_buffer[2];
switch (message_id){
case SYNC_PKT:
{
bool adjustment_procedure_started;
sync_pkt_t *p_pkt;
p_pkt = (sync_pkt_t*)&m_rx_payload_buffer[2];
adjustment_procedure_started = sync_timer_offset_compensate(p_pkt);
/*if (adjustment_procedure_started) {
p_pkt = tx_buf_get();
}*/
clear_events_restart_rx();
}
break;
case URLLC_DATA_PKT:
if (on_radio_disabled)
{
on_radio_disabled();
}
break;
}
}
}
