CODEWITHSUNDEEP
pythonraspberry-pimicropythonraspberry-pi-pico
merit_2
merit_2

Reputation: 471

UART communication Raspberry Pi Pico to Raspberry Pi

I am trying to communicate with a raspberry pi pico with my raspberry pi 4 over uart. The below code does transmit data, but I am only receiving data from the print statement.

 import os
    import utime
    from machine import ADC
    
    temp_sensor = ADC(4) # Default connection of temperature sensor


def temperature():
    # get raw sensor data 
    raw_sensor_data = temp_sensor.read_u16()
    
    # convert raw value to equivalent voltage
    sensor_voltage = (raw_sensor_data / 65535)*3.3
    
    # convert voltage to temperature (celcius)
    temperature = 27. - (sensor_voltage - 0.706)/0.001721
    
    return temperature
    

#print setup information :
print("OS Name : ",os.uname())

uart = machine.UART(0, baudrate = 9600)
print("UART Info : ", uart)
utime.sleep(3)

while True:
    temp = temperature()
    print(str(temp))
    uart.write(str(temp))
           
    utime.sleep(1)

And the code on my raspberry pi 4 is:

import serial
import time
import numpy as np
import matplotlib.pyplot as plt

#ser = serial.Serial('COM14',9600)
ser = serial.Serial('/dev/ttyACM0', 9600)

time.sleep(1)


while True:
    # read two bytes of data
    #data = (ser.read(8))
    data = (ser.readline())
    # convert bytestring  to unicode transformation format -8 bit
    temperature = str(data).encode("utf-8")
    #print("Pico's Core Temperature : " + temperature + " Degree Celcius")
    print(temperature)

The output in the terminal on my RPI 4 is:

27.2332

26.443

26.443

26.564

There is an extra new line between. If I remove print(str(temp)) from the pico code I get nothing. I can put just about anything in uart.write(str(temp)) and still receive the print statement, but without the uart.write() I will receive nothing.

Upvotes: 2

Views: 6080

Answers (1)

rami atallah
rami atallah

Reputation: 139

  1. extra new line: this problem is just because the print ends with new line you can change print(str(temp)) to print(str(temp), end="") in raspberry pi pico code

  2. with respect to your second problem I don't think that uart.write(str(temp))is doing something useful. print statement is the way to send data to raspberry pi

A way I use to send data to raspberry pi is:

  • raspberry pi pico send the number of chars of the message then send the message
    while True:
        temp = temperature()
        print(len(str(temp)))
        utime.sleep(1)
        print(str(temp))
        utime.sleep(1)

the length would be between 1 and 9 so raspberry pi will receive 1 char in raspberry pi code

    while True:
        # read length of data
        length = int(ser.read(1).encode("utf-8"))
        # read the data
        data = (ser.read(length))
        #convert bytestring  to unicode transformation format -8 bit
        temperature = str(data).encode("utf-8")
        print(temperature)

Upvotes: 0

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