Legal Removal Request

Post: I'm glad you have working communication between your Raspberry Pi and ESP32 module. The Raspberry Pi code I used was the program you posted in your second post. [pre][code]import serial, time if __name__ == '__main__': ser = serial.Serial('/dev/ttyAMA0', 115200, timeout=1) ser.flush() while True: ser.write(b"Hello from Raspberry Pi!\n") line = ser.readline().decode('utf-8', errors="ignore").rstrip() print(line) time.sleep(1)[/code][/pre] The error you are getting looks like something is trying to access the serial port at the same time as your program. In your /boot/cmdline.txt file are there any references to ttyS0, serial0 or ttyAMA0? If there are remove them and that should fix the problem. If that is not the issue then there may be another process running that is trying to send data to the serial port.