Getting a Com Port serial reading in a certain period of time

Question

I'm taking my first steps in Python programming. I'm using a TFMini Plus Lidar connected to a Windows 7 computer through a USB to TTL serial connection.

I'm getting readings through this code:

import time
import serial
import datetime
import struct
import matplotlib.pyplot as plt

ser = serial.Serial(
        port="COM1",
        baudrate = 115200,
        parity=serial.PARITY_NONE,
        stopbits=serial.STOPBITS_ONE,
        bytesize=serial.EIGHTBITS,
        timeout=1
)

while 1:
        x = ser.readline().decode("utf_8").rstrip('\n\r')
        y=float(x)
        print(y)
        #time.sleep(0.1)
        if y > 3:
                print("too far!")

I want to have a single reading every X second (that can be set as per user choice), but I cannot find a way to do it. When I use time.sleep(), the readings get all the same:

Readings with time.sleep on

Basically i want to delay the frequency of readings or make it to selectively give me a single reading from the ones captured. How can I do it?

Thanks

Answer 1

You could use the schedule package. I.e.:

import time
import serial
import schedule

ser = serial.Serial(
        port="COM1",
        baudrate = 115200,
        parity=serial.PARITY_NONE,
        stopbits=serial.STOPBITS_ONE,
        bytesize=serial.EIGHTBITS,
        timeout=1
)

def read_serial_port():
    x = ser.readline().decode("utf_8").rstrip('\n\r')
    y=float(x)
    print(y)
    if y > 3:
        print("too far!")

rate_in_seconds = 10
schedule.every(rate_in_seconds).seconds.do(read_serial_port)

while True:
    schedule.run_pending()
    time.sleep(1)