uart_tunnel.c

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#include "LPC21xx.h"

#include "std.h"

#include "mcu.h"
#include "led.h"

#define TXD0_PIN 0
#define RXD0_PIN 1
#define TXD1_PIN 8
#define RXD1_PIN 9

int main(int argc __attribute__((unused)), char **argv __attribute__((unused)))
{
  int tx = 0, rx = 0;
  int tx_shadow = 1, rx_shadow = 1;
  mcu_init();
  led_init();
#if USE_LED_1
  LED_ON(1);
#endif

  /* TXD0 and TXD1 output */
  SetBit(IO0DIR, TXD0_PIN);
  SetBit(IO0DIR, TXD1_PIN);

  /* RXD0 and RXD1 input */
  ClearBit(IO0DIR, RXD0_PIN);
  ClearBit(IO0DIR, RXD1_PIN);

  /* use shadow bits to reduce jitter */
  while (1) {
    tx = bit_is_set(IO0PIN, RXD0_PIN);
    if (tx != tx_shadow) {
      if (tx) {
        SetBit(IO0SET, TXD1_PIN);
      } else {
        SetBit(IO0CLR, TXD1_PIN);
      }
      tx_shadow = tx;
#if USE_LED_2
      LED_TOGGLE(2);
#endif
    }
    rx = bit_is_set(IO0PIN, RXD1_PIN);
    if (rx != rx_shadow) {
      if (rx) {
        SetBit(IO0SET, TXD0_PIN);
      } else {
        SetBit(IO0CLR, TXD0_PIN);
      }
      rx_shadow = rx;
#if USE_LED_3
      LED_TOGGLE(3);
#endif
    }
  }
  return 0;
}