pyserial连接到串口上的android没有响应

Question

Trying to communicate with an android device on a serial port. I can establish a connection through pyserial, but I don't understand how the flow of information works and why I can't get any output (or when I should expect output). As a check, I can log into the device using minicom or python3 -m serial.tools.miniterm and get the expected output from things like pwd and echo hello . My basic code:

import serial
ser = serial.Serial("/dev/ttyS0")
ser.write(b'echo hello')
ser.inWaiting()
ser.write(b'pwd')
ser.inWaiting()
# print(ser.readLine().decode())

ser.inWaiting() returns 0 both times it's called, so there's no point in trying to read anthing.

I would greatly appreciate any discussion of fundamentals that I seem to be missing. Thank you.

Answer 1

Compare your port , baudrate , parity and stopbits with the minicom setting and pass those keywords to serial.Serial . You did not set a baudrate and serial.Serial 's default of 9600 B is probably wrong. 115200 B would be my first guess.

On a general note:

1. The short introduction shows the usage of pyserial .
2. When reading a fixed number of bytes with read() or until and end of line character with read_until , ensure that the timeout is not set too low.
3. Ensure that only one instance open and closes the serial port. A port can be opened multiple times, but that leads to unexpected behavior.
4. When using inWaiting() you to wait a while for the answer first(300 ms would be good starting point)—serial communication is so slow!

Answer 2

The return of ser.inWaiting will be the number of bytes on input buffer. The code below writes your first message and waits if something is entered on input buffer then will read what come to you:

import serial
ser = serial.Serial("dev/ttyS0")
while 1:
    ser.write(b'echo hello')
    if ser.inWaiting()>0:
        ser.read(32)# the argument is the number of bytes to read