In my nybble, I can write from the Raspberry Pi but cannot read it through serial communication between NyBoard V0_2 and RaspberryPi 3B+.
Serial communication is enabled and console is disabled in the rasbian settings.
After running the python code below, I get nothing when I run ser.readline ().
ser = serial.Serial (
    port = '/dev/ttyAMA0',
    baudrate = 57600,
    parity = serial.PARITY_NONE,
    stopbits = serial.STOPBITS_ONE,
    bytesize = serial.EIGHTBITS,
    timeout = 1
)
However, nybble works normally when I execute the following command.
echo "kbalance"> /dev/ttyAMA0
On the other hand, the following command does not display anything
cat /dev/ttyAMA0
Why can I write to nybble but not read it from my Raspberry Pi? Is it likely a hardware problem?
I used the following tools on my Raspberry Pi and confirmed that GPIO # 14 and # 15 are true.
https://github.com/kgbplus/gpiotest
You can run the ardSerial.py as a bash script in the terminal. For example:
python ardSerial.py ktrwill have the same effect as entering ktr in the serial monitor. It should also read and print the returning serial signal in the terminal.
If it can both read and write the serial port, then it's probably some software issue when you use the commands.