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BlueNRG - Throughput Limitation

Question asked by mattos.willian on Jun 24, 2017
Latest reply on Aug 1, 2017 by mattos.willian

Dear Colleagues,

 

I'm developing a real time application which I need around 128 kbps of BLE application throughput.

 

Inside BlueNRG package there is a Throughput demo that shows how to implement a simple throughput test between two BlueNRG devices. In my case I have configured the following scenario:

 

STM32L053R8+IDB04A1 (as a SERVER) and STM32F030R8+IDB05A1 (as a CLIENT),

 

The throughput demo used is the 'SampleAppThT' with THROUGHPUT_TEST parameter defined in both sides (V2.8.0 / 10-Feb-2017) . Using the original code  I got around 155 kbps in the throughput test (only calculated by the SERVER side).

 

After this, I only did the following changes in the original code provided by ST:

 

1) Uncomment PRINTF command --> SERVER SIDE (sample_service.c)

while(aci_gatt_update_char_value(sampleServHandle, TXCharHandle, 0, 20, data)==BLE_STATUS_INSUFFICIENT_RESOURCES) {
// Radio is busy (buffer full).
PRINTF("Radio is busy (buffer full)\n");
if(Timer_Expired(&t)) {
break;
}

 

2) Uncomment PRINTF command --> CLIENTE SIDE (sample_service.c)

n_packet2 = LE_TO_HOST_32(attr_value+16);
if(n_packet2 != n_packet1 + 1){
lost_packets += n_packet2-(n_packet1+1);
}
n_packet1 = n_packet2;
packets++;
PRINTF("packet %d\n", packets);

 

However, after uncomment the PRINTF lines I've realized that after around 230 packets, the CLIENT side stops to receive packets and therefore the throughput calculated by the SERVER considered only the 'sent packets' .

I can see that when the SERVER busy (the output queue is fulland even so the SERVER try to send the packets the connection is dropped or the CLIENT simply does not receive anything.

 

I could verify the event EVT_BLUE_GATT_TX_POOL_AVAILABLE added in BlueNRG-MS FW stack 7.1c for avoiding continuous polling until BLE_STATUS_INSUFFICIENT_RESOURCES is returned. See: https://community.st.com/thread/33358

 

However, I don't think that this verification could increase the throughput (as the server will need to wait until the queue is free).

 

As the CLIENT does not receive at least the 500 packets, is not possible to correctly evaluate the real throughput in the CLIENT side.

 

After the explanation I have the following questions:

 

1) What's is the maximum throughput provided BLUENRG in the CLIENT side? (As the maximum throughput in demo provided by ST is only showed in the SERVER side).

 

2) Does anyone have a working solution which could achieve the maximum theoretical BLE rate with BLUENRG? (Around 128Kbps).

 

PS.: I also attached the results provided by Serial terminal showing the results.

 

Many Thanks.

 

BR,

 

Willian Mattos

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