Unreliable communication with tinyproto

[redemption95]

I am unable to get reliable data transmission at a bit higher baud rate: 115200, 57600. Enabled crccheck16() on both sides.

Send : Rpi python

ser = serial.Serial('/dev/ttyS0', 115200, parity = serial.PARITY_NONE, timeout= 0)

while True:
    buf = bytearray([ 0x7E, 0xFF, 0x3F, 0xF3, 0x39, 0x40, 0x7E  ])
    buf = "SAM\0"
    buf = "HELLO-WORLD\0"
    print("Writing byte array to serial")
    print(p.put(buf)) #bytearray([ 0x7E, 0xFF, 0x3F, 0xF3, 0x39, 0x7E  ])
    # print(p.tx())
    ser.write(p.tx())

Receive: Arduino

#include <TinyProtocol.h>
#include <SoftwareSerial.h>

int buff[256];
tinyproto::Hdlc proto_hdlc(buff, 256);
SoftwareSerial mySerial(A3, A2);

void hdlcRecieveCallback(tinyproto::IPacket &pkt)
{
    //Recive and process packets
    Serial.println("HDLC Recieve callback");
    Serial.println(pkt.getString());
    Serial.println("Recieved data size : " + String(pkt.size()));
    Serial.println("Max buffer size : " + String(pkt.maxSize()));
    Serial.println("=========================");
}
void setup() {
    /* No timeout, since we want non-blocking UART operations. */
    Serial.setTimeout(0);
    mySerial.setTimeout(0);
    /* Initialize serial protocol for test purposes */
    Serial.begin(115200);
    mySerial.begin(9600);
    proto_hdlc.setReceiveCallback(hdlcRecieveCallback);
    proto_hdlc.begin();
    proto_hdlc.enableCrc16();
}

void loop()
{

    size_t len =   mySerial.available();  
    // char bytes[128];
    if (len) {
        uint8_t bytes = mySerial.read();
        proto_hdlc.run_rx( &bytes, 1 );
        // mySerial.readBytes(bytes,len > 128 ? 128 : len);
        // proto_hdlc.run_rx( bytes, len > 128 ? 128 : len ); // run FD protocol parser to process data received from the channel
    }
}

Baud: 115200 Zero reliability

More reliable than above. But still unacceptable to the requirement. Baud : 57600

Most reliable Still too many error packets Baud : 9600

Am I doing something wrong. or the observation is correct.

Thank you in advance. Sasank Panda

[lexus2k]

Hi Sasank,

did you try examples from examples folder? Do they work on your setup? As I wrote earlier in another github issue #20: Also, I would recommend to carefully test Software Serial library communication, because unlike Hardware implementation, the Software one may miss some bits due to higher load off AVR MCU. Even printing debug information to hardware Serial Serial.println("HDLC Recieve callback"); in the hdlcRecieveCallback callback eats the resources of AVR MCU.

Since, you're using Software Serial on the weak micro controller, this could be a root cause. You can try to switch to more powerful hardware.

[redemption95]

Yes, I tried, I did finally change to AltSoftSerial the second-best to hardware as I managed to get pin 8,9 free. There I observed I was writing to the buffer too fast (probably faster CPU of RPi ), than the Arduino can empty the buffer. I managed to get good reliability adding some delay although I am not convinced with the solution. But yes no issues with the library functionality.

Thank you , Sasank Panda