RS232 handshaking

Projects Networking, Protocols, and Devices
1

This is part of my code

#include <LiquidCrystal.h>
LiquidCrystal lcd(8,9,4,5,6,7);
const int sw1 = 3;
int zn;
int x=0;

void ini_comm(){
Serial.end();
Serial.begin(2400);
UCSR0C = ( UCSR0C & ~_BV(UPM00) | _BV(UPM01) );
} //UPM01=1 --> Parity on UPM00=0-->Even

void setup() {
lcd.begin(16, 2);
pinMode(sw1, INPUT);
digitalWrite(sw1,HIGH);
lcd.print("1 start ");
lcd.setCursor(0, 1);
}

void loop(){
if(digitalRead(sw1)==LOW)
{
delay(1000);
lcd.clear();
ini_comm(); // ini comm
Serial.write(0xF4);
Serial.write(0x03);
Serial.write(0x51);
Serial.write(0x0A);
Serial.write(0xAC);
}
if (Serial.available() > 0) {
zn = Serial.read();
lcd.print(zn,HEX);
lcd.print(' ');
}
}

I don't have reply on LCD ( terminal show repply ).
It looks like RX start with little latency. Why ?

2

maybe cause you delay for a second, which stops your whole program?

3

Delay is only for switch. ( no repeating ini comm ).
It does not matter for reciving !!!!!!!!
ini_comm(); // ini comm
Serial.write(0xF4);
Serial.write(0x03);
Serial.write(0x51);
Serial.write(0x0A);
Serial.write(0xAC);

When I send F4 03 51 0A AC I see response on terminal but don't see on LCD !!!