how to make a reliable consecutive transmission over UART

RE: how to make a reliable consecutive transmission over UART

leo.lau — Tue, 26 Jan 2021 06:43:45 GMT

Thank you so much for the suggestions.

The problem actually related to the event length.

Hope this code helps the people with similar questions.

In sdk_config.h

#define NRF_SDH_BLE_GAP_EVENT_LENGTH 3

void conn_evt_len_ext_set(bool status)
{
    ret_code_t err_code;
    ble_opt_t  opt;

    memset(&opt, 0x00, sizeof(opt));
    opt.common_opt.conn_evt_ext.enable = status ? 1 : 0;

    err_code = sd_ble_opt_set(BLE_COMMON_OPT_CONN_EVT_EXT, &opt);
    APP_ERROR_CHECK(err_code);

    m_test_params.conn_evt_len_ext_enabled = status;
}


int main(void){
    ...
    conn_evt_len_ext_set(true);
}

RE: how to make a reliable consecutive transmission over UART

Kenneth — Tue, 01 Dec 2020 17:17:36 GMT

Adding additional BLE peripheral links are in essence just more high priority interrupts that cause more frequent pending of code execution in the application main() and interrupts. I am not sure where to begin to debug here, but adding a counter in the buffer, could make it easier to catch that the same nrf_libuarte_async_tx() was called two times with the same counter. That could be a start to narrow it down?

RE: how to make a reliable consecutive transmission over UART

leo.lau — Tue, 01 Dec 2020 12:03:13 GMT

Because the problems is getting worse when two peripherals connected.

1 peripheral:

total time	117.73
total packet	11774
repeated packet	2
CRC erorr	0

2 peripherals,

	p1	p2
total time	53.9	53.58
total packet	5393	3528
repeated packet	137	862
CRC erorr	-3	1830

Receiving side is a PC running Python. It keeps checking inWaiting() and printing out the value.

I don't think my pc is slower than a DK...

Here is the testing code.

import binascii

import serial
import serial.tools.list_ports as ports
import time
import sys
import threading
import queue


inputQueue = queue.Queue()


def receive_thread(com, inputQueue):
    while com:
        if com.inWaiting() > 0:
            line = com.readline()
            hex_str = ""
            for i in range(len(line)):
                hex_str += chr(line[i])
            print(hex_str)
            
            try:
                (int(hex_str, 16))     # check CRC 
                if len(hex_str) == 74: # check string legnth
                    inputQueue.put(hex_str)
            except ValueError:
                print("ValueError")


def convert_data_thread(inputQueue):
    # convert and log data in another thread
    

if __name__ == "__main__":
    port = serial.tools.list_ports.comports()[0].device

    com = serial.Serial(port=port,
                        baudrate=460800,
                        parity=serial.PARITY_NONE,
                        stopbits=serial.STOPBITS_ONE,
                        bytesize=serial.EIGHTBITS,
                        rtscts=True,
                        timeout=1)

    if com is None:
        print("cannot open serial port")
        sys.exit()
        
    t1 = threading.Thread(target=receive_thread, args=[com, inputQueue])
    t1.daemon = True
    t1.start()
    convert_data_thread(inputQueue)

RE: how to make a reliable consecutive transmission over UART

awneil — Mon, 30 Nov 2020 17:49:26 GMT

[quote userid="81755" url="~/f/nordic-q-a/68936/how-to-make-a-reliable-consecutive-transmission-over-uart"]

sometimes the DK transmitting repeat data and sometimes error data is sent(missing 1 byte).

[/quote]

How do you know that the problems are in the DK ... ?