random corrupted data in serial Arduino - serialization

Question

I have issue to read serial data from Arduino Uno in UWP C#. Sometimes when I start app I get corrupted data.
But in arduino monitor always is good.
Corrupted data is like this:
57
5
But should be 557.
Arduino codes:
String digx, digx2, digx3, digx1 ;
void setup() {
delay(500);
Serial.begin(9600);
}
void loop() {
int sensorValue = analogRead(A1);
sensorValue = map(sensorValue, 0, 1024, 0, 999);
digx1 = String(sensorValue % 10);
digx2 = String((sensorValue / 10) % 10);
digx3 = String((sensorValue / 100) % 10);
digx = (digx3 + digx2 + digx1);
Serial.println(digx);
Serial.flush();
delay(100);
}
And windows universal codes:
public sealed partial class MainPage : Page
{
public DataReader dataReader;
public SerialDevice serialPort;
private string data;
private async void InitializeConnection()
{
var aqs = SerialDevice.GetDeviceSelectorFromUsbVidPid(0x2341, 0x0043);
var info = await DeviceInformation.FindAllAsync(aqs);
serialPort = await SerialDevice.FromIdAsync(info[0].Id);
Thread.Sleep(100);
serialPort.DataBits = 8;
serialPort.BaudRate = 9600;
serialPort.Parity = SerialParity.None;
serialPort.Handshake = SerialHandshake.None;
serialPort.StopBits = SerialStopBitCount.One;
serialPort.ReadTimeout = TimeSpan.FromMilliseconds(1000);
serialPort.WriteTimeout = TimeSpan.FromMilliseconds(1000);
Thread.Sleep(100);
dataReader = new DataReader(serialPort.InputStream);
while (true)
{
await ReadAsync();
}
}
private async Task ReadAsync()
{
try
{
uint readBufferLength = 5;
dataReader.InputStreamOptions = InputStreamOptions.Partial;
//dataReader.UnicodeEncoding = UnicodeEncoding.Utf8;
var loadAsyncTask = dataReader.LoadAsync(readBufferLength).AsTask();
var ReadAsyncBytes = await loadAsyncTask;
if (ReadAsyncBytes > 0)
{
data = dataReader.ReadString(ReadAsyncBytes);
serialValue.Text = data;
}
}
catch (Exception e)
{
}
}
}
My idea was if it happened, Program skip that data. I tried different buffer length but more or less than 5 will always receive incorrect.
Thanks for any help.

Answer 1

Two methods that can fix your problem.
Method1: Make your UART communication robust
That there is no chance of an error but this is a tricky and time-consuming task in the case of windows software communicating with Arduino.
But still have some tricks which can help you because I have tried them and some of them work but please don't ask for the reason why it works.
Change your UART baud rate from 9600 to something else (mine if works perfect at 38400).
Replace Serial.begin(9600); to Serial.begin(38400,SERIAL_8N1)where 8 is data bit, 1 is stop bit and N is parity none in SERIAL_8N1. And you can also try different settings in data bit, stop bit, and parity. check here
don't send data after converting it into a string Serial.println(digx);. Send data in form of bytes array use Serial.write(digx,len);. check here
Method2: Add CRC Packet
At the end of each data packet and then send. When it reaches the windows software first fetch all UART data then calculate CRC from that data and then just compare calculated CRC and received CRC.If CRC matches then the data is correct and if not then ignore data and wait for new data.
you can check for CRC calculation its direct formula base implement and for little head start check this library by vinmenn.

Answer 2

I used two things to fix the problem,
1. In Windows codes added SerialDevice.IsDataTerminalReadyEnabled = true property to read bytes with correct order. From Microsoft docs
Here's a link!
2. As dharmik helped, I used array and send it with Serial.write(array, arrayLength) in Arduino and read them with dataReader.ReadBytes(array[]) and right buffer size in Windows app.
And result is so stable even with much lower Delays.