RS232 Transmission

16/Jul/2023

Windows

Connection

USB-SERIAL CH340 adapter pinout:

• 2 RX
• 3 Tx
• 5 GND

Sending data

Python example to write data to the serial port from Windows:

import serial
import time

ser = serial.Serial(
    port='COM3',\
    baudrate=9600,\
    parity=serial.PARITY_NONE,\
    stopbits=serial.STOPBITS_ONE,\
    bytesize=serial.EIGHTBITS,\
    timeout=0)

while(1):
    ser.write(b'\x00\x80\xaa\xff')
    time.sleep(1)

ser.close()

Waveforms

In this adapter, the idle level is low:

Arduino Duemilanove

Connection

Digital pin 1 and gnd.

Sending data

Arduino example to write to the serial port:

void setup() {
  Serial.begin(9600);
}

void loop() {
  char data[4] = {0x0, 0x80, 0xaa, 0xff};
  Serial.write(data, 4);
  delay(500);
}

Waveforms

Idle level is high: