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#define RX_ENABLE_PIN 4
#define TX_ENABLE_PIN 16
#define DEBUG_PIN 13
void setup()
{
pinMode(RX_ENABLE_PIN, OUTPUT);
pinMode(TX_ENABLE_PIN, OUTPUT);
pinMode(DEBUG_PIN, OUTPUT);
digitalWrite(DEBUG_PIN, LOW); //disable led
digitalWrite(RX_ENABLE_PIN, LOW); //always listen.
Serial.begin(38400);
}
void loop()
{
if (Serial.available())
{
byte i = Serial.read();
rs485_tx(i);
digitalWrite(DEBUG_PIN, HIGH);
delayMicroseconds(100);
digitalWrite(DEBUG_PIN, LOW);
}
}
void rs485_tx(byte b)
{
transmit_mode();
Serial.print(b, BYTE);
int tmp = Serial.read();
while (tmp != b)
tmp = Serial.read();
receive_mode();
}
void transmit_mode()
{
digitalWrite(TX_ENABLE_PIN, HIGH); //enable tx
}
void receive_mode()
{
digitalWrite(TX_ENABLE_PIN, LOW); //disable tx
}
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