facing issues with hardware UART port in raspberry

[Abu_Abdullah]

Hi,

I'm trying to connect to external controller via the hardware UART pins in raspberry. the serial receives the data in broken way in onNewSerialDataAvailable(byte[] inBuf).

How can i troubleshoot this issue. I'm using the standard code below:

try
{
   serial = new SerialComManager();
   
   String PORT = "/dev/ttyS0"; 
// "/dev/ttyUSB0"  via UART1:USB      

   comPortHandle = serial.openComPort(PORT, true, true, true);
   serial.configureComPortData(comPortHandle, DATABITS.DB_8, STOPBITS.SB_1, PARITY.P_NONE, BAUDRATE.B115200, 0);
   serial.configureComPortControl(comPortHandle, FLOWCONTROL.NONE, 'x', 'x', false, false);

   // register data listener for this port
   serial.registerDataListener(comPortHandle, this);
}
catch (Exception e)
{
   e.printStackTrace();
   if(comPortHandle != -1)
      try {serial.closeComPort(comPortHandle);} catch (Exception e1) {}
   return;
}

[Abu_Abdullah]

listening to the serial via USB (USB-UART from both sides raspberry and the external controller) is working fine but not working if using the hardware UART pins in both sides.

[Rishi Gupta]

May you please share exact hardware details like pin number of rpi, rpi2 or rpi3, connection details like rpi --> ft233 -> which controller etc. so that I can understand further. Also how one end sends data to other.

[Abu_Abdullah]

sure,

Raspberry Pi 3, GPIO 14 (TX) & 15 (RX)
those are the UART pins, it is connected to UART2 - RMRC Seriously Dodo Flight Controller 

attached are the layout for both

in raspberry pi 3, the same pins are used for both bluetooth and serial:
/dev/ttyAMA0 (hardware high performance UART)
/dev/ttyS0 (software low performance UART)

ttyS0 is the default for serial but can be switched with the hardware. i tried both of them. for switching i was following:
http://spellfoundry.com/2016/05/29/configuring-gpio-serial-port-raspbian-jessie-including-pi-3/

the UART-USB that is working is connected in the controller to the USB which is connected internally to UART1 and to one of raspi usb ports.

[Abu_Abdullah]

there is a possibility that the issue is from the controller firmware and not raspi or serialpundit. I will check this

[Abu_Abdullah]

ok, after some troubleshooting, the serial stream is received in chunks of 8 or 5 bytes and not in a clean way as in the USB-UART. i modified my code so that it will merge bytes together.

I'm not sure if this is an issue in the controller or something else but this workaround is enough at this stage. thanks