Maximizing Gazelle Data Throughput

RE: Maximizing Gazelle Data Throughput

jcondon — Mon, 27 Jul 2015 16:12:35 GMT

I haven't done thorough testing on the 2Mbps mode, as I'd prefer to maintain the range of the 1Mbps mode. I'll be doing testing on the 2Mbps mode later this week and can post results.

RE: Maximizing Gazelle Data Throughput

Hung Bui — Mon, 27 Jul 2015 07:55:20 GMT

@jcondon: Have you tried to change the datarate to 2Mbps and reduce the timeslot to 600us?

RE: Maximizing Gazelle Data Throughput

jcondon — Mon, 27 Jul 2015 05:27:57 GMT

I gave this a shot. Unfortunately I didn't see any noticeable change in the throughput. Is there anything else I could try or another test to run?

RE: Maximizing Gazelle Data Throughput

Brian — Mon, 06 Jul 2015 06:01:48 GMT

Hey guys, I have a similar setup (code below on device side), with the Gzll parameters printed out below: However, I'm only able to get a throughput of 41kpbs. What might I be missing here? Thanks!

    while(ImageTxIdx < ImageDataSize){

      if(nrf_gzll_ok_to_add_packet_to_tx_fifo(PIPE_NUMBER)) {

          for(uint8_t i=0;i<32;i++)
            data_payload[i] = ImageData[ImageTxIdx++];

          ret = nrf_gzll_add_packet_to_tx_fifo(PIPE_NUMBER, data_payload, 32);

          if(ret == false){
            TxErrCnt++;
            SEGGER_RTT_printf(0, "TxErrCnt:%d\n", TxErrCnt);
          }                                                                                                       
      }
    }

//device

nrf_gzll_get_datarate: 2

nrf_gzll_get_timeslot_period: 600

NRF_GZLL_CONST_MAX_PAYLOAD_LENGTH: 32

nrf_gzll_get_timeslots_per_channel: 2

nrf_gzll_get_sync_lifetime: 30

nrf_gzll_get_channel_table_size: 5

nrf_gzll_get_tx_power: 1

//host

nrf_gzll_get_datarate: 2

nrf_gzll_get_timeslot_period: 600

NRF_GZLL_CONST_MAX_PAYLOAD_LENGTH: 32

nrf_gzll_get_timeslots_per_channel: 2

nrf_gzll_get_sync_lifetime: 30

nrf_gzll_get_channel_table_size: 5

nrf_gzll_get_tx_power: 1

RE: Maximizing Gazelle Data Throughput

ovrebekk — Fri, 03 Jul 2015 09:03:35 GMT

The max data rate in Gazell is actually (1/(2*TimeslotPeriod))*PayloadSize, which should be 142kbps for the settings you use. This means you are quite close when using 2 slots per channel, and the reason you are not getting closer is probably that you lose sync on occasion.

For a higher data rate than this you would probably have to use 2Mbps data rate instead, allowing you to get away with a shorter timeslot.

One thing you can try to reduce the chance of losing sync is to make the timeslot on the device side slightly shorter than on the host side. In general it is better for the device to drift to the left of the timeslot than to the right, and this might improve performance. You can try to reduce the device timeslot with values in the 5-50 range for a start.

Best regards Torbjørn