Burst transmission triggered many times

Question

I am doing burst transfers using exactly the code suggested here devzone.nordicsemi.com/.../ 
 The problem is, the data is received three times by the receiver (three times the same packet) 
 Additional info: 
 
 I have a registered a callback function on ANT events on the transmitter, and during transmission it triggers only once event 0x0a (EVENT_TRANSFER_TX_START) and 0x05 (EVENT_TRANSFER_TX_COMPLETED) 
 On the receiver (AntWare II) the packet indexes are consecutive, as if it was only a single burst transmission (i.e. if the burst transmission is 2 * 8 bytes, indexes are 0x00, 0x20, 0x30, 0x60, 0x20, 0xc0); 
 The only difference I reckon, my m_burst_data[] is bigger than the real data, and I use the second argument of sd_ant_burst_handler_request(..) for telling how many bytes to send (always multiple of 8). That way, I can send almost arbitrary length data - is that a legit usage? I'd like to avoid using heap and malloc. - EDIT: even with an array of the right size, the problem persists. 
 
 EDIT #2: 
 reference code: 
 do
{
err_code = sd_ant_burst_handler_request(CHANNEL_0, sizeof(m_burst_data), m_burst_data, BURST_SEGMENT_START); 
} while (err_code == NRF_ANT_ERROR_TRANSFER_IN_PROGRESS);

APP_ERROR_CHECK(err_code);
while(burst_wait)
;


err_code = sd_ant_burst_handler_request(CHANNEL_0, sizeof(m_burst_data), m_burst_data, BURST_SEGMENT_CONTINUE);
APP_ERROR_CHECK(err_code);
while(burst_wait)
;


err_code = sd_ant_burst_handler_request(CHANNEL_0, sizeof(m_burst_data), m_burst_data, BURST_SEGMENT_END); 
APP_ERROR_CHECK(err_code);
while(burst_wait)
;
 
 If I comment the middle "sd_ant_burst_handler_request(... BURST_SEGMENT_CONTINUE)" section, the burst transmission happens 'only' 2 times. 
 I I comment both the middle section and the last "sd_ant_burst_handler_request(... BURST_SEGMENT_END)", the burst is received once, but the receiver triggers a EVENT_TRANSFER_RX_FAILED_0x04 
 Has anyone an idea about how sd_ant_burst_handler_request() is supposed to work and what it specifically does? Why have I found also a version without BURST_SEGMENT_CONTINUE somewhere in the thisisant website?
 www.thisisant.com/

testy · Accepted Answer

This works for me to send 64 bytes of 72: 
 uint8_t m_burst_data[72];
err_code = sd_ant_burst_handler_request(CHANNEL_1, ((sizeof(m_burst_data))-8), m_burst_data, (BURST_SEGMENT_START | BURST_SEGMENT_END));
 
 Consider: 
 Burst: the last packet of the burst will be retransmitted on the next channel period if ANT has not received any new data from the master’s host MCU.
Advanced Burst: the first packet of the burst will be retransmitted on the next channel period if ANT has not received any new data from the master’s host MCU.
Unlike normal burst transfers, the retransmitted data will be the first packet of the burst (the initial 8-byte normal burst packet). 
 That's for nRF51 master (sends Advanced Burst) -> ANT AP2 81M5IB slave (Burst only capable device): 
 
 It's funny, but after I figured this line of code out, today I found exactly the same solution here . 
 This can help too.