[Tutor] Serial communication problem

[Phil]

Thank you Alan, Cameron and Rauf for your replies.

I know that the "1" and "0" are received by the pico because the LED 
turns on and off.

I know that the "ok" ready signal is sent by the pico because the python 
code prints "ok".

The pico seems to be ignoring the "s" sent by the python code, I'm not 
certain of that. Debugging the running  pico code is difficult, I'm 
relying on print statements.

The delays are sprinkled among the code just to be sure that the serial 
transmissions aren't being overwhelmed. The delays haven't helped.

Here is the latest python code:

# synchronised write and read to and from the pico

import time
import serial

with serial.Serial("/dev/ttyACM0", 9600) as ser:
     while True:
         for char in (b"1", b"0"):
             ser.write(char)
             time.sleep(1)


             # Wait for acknowledgment
             while True:
                 print("in the loop")

                 ready = ser.readline().decode().strip("\r\n")
                 print(ready)

                 if ready == "ok":
                     print(f"after if: {ready}")

                     time.sleep(1)
                     #ser.flush()
                     #ser.reset_input_buffer()
                     #ser.reset_output_buffer()
                     break

             ser.write(b"s")
             print("outside the loop")
             time.sleep(2)

             data = ser.readline().decode().strip("\r\n")
             print(f"Received: {data}")

             time.sleep(1)
             print()
             print()

And here is the pico code:

import uselect
import sys
import machine
import utime


class LEDController:
     def __init__(self):
         self.led = machine.Pin('LED', machine.Pin.OUT)
         self.led_status = 'led off'

     def set_led_status(self, new_ch):
         if new_ch == '1':
             self.led.value(1)
             self.led_status = 'led on'
             #print(self.led_status)
         elif new_ch == '0':
             self.led.value(0)
             self.led_status = 'led off'

     def get_led_status(self):
         return self.led_status
         #return "X"

     def read_char(self):
         poll_obj = uselect.poll()
         poll_obj.register(sys.stdin,1)

         if poll_obj.poll(0):
             #read one character
             ch = sys.stdin.read(1)
         else:
             ch = None
         return ch

     def send_acknowledgement(self):
         print('ok')

controller = LEDController()

while True:
     new_ch = controller.read_char()
     print(new_ch)

     if new_ch is not None:
         controller.set_led_status(new_ch)
         controller.send_acknowledgement()

         # After sending acknowledgement, get LED status
         status_request = controller.read_char()
         #utime.sleep(1)
         #print(status_request)

         #status_request = 's'
         if status_request == 's':
             led_status = controller.get_led_status()
             print(led_status)
             #print("Z")

utime.sleep(.5)

I just ran this project and I see the LED is not blinking, so I've 
stuffed something up. I've got a medical appointment so I've go to scoot.

I'm sorry to be such a pest.

-- 

Regards,
Phil