C# Serial Port + CCS C Serial Port + PIC 16F877A

Question

I have a PIC 16F887A connected to the serial port. I want it to lit a green led when it receives 0x01 and lit a red led when it receives 0x00 from pc. I send the characters from a C# windows forms application, the PIC itself is programmed with CCS C. Can you please tell me what i'm doing wrong as the codes below don't work?

Edit: By doesn't work i mean it lits the red led in both cases.

C# Code

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;
using System.IO.Ports;

namespace deneme
{
    public partial class Form1 : Form
    {
        SerialPort port = new SerialPort("COM2", 9600, Parity.None, 8, StopBits.One);
        public Form1()
        {
            InitializeComponent();
        }

        private void openportbtn_Click(object sender, EventArgs e)
        {
            if (port.IsOpen)
            {
                port.Close();
            }

            if (!port.IsOpen)
            {
                port.Open();
            }
        }

        private void rightbtn_Click(object sender, EventArgs e)
        {
            byte[] right = new byte[1];
            right[0] = 0x01;
            port.Write(right, 0, right.Length);
        }

        private void wrongbtn_Click(object sender, EventArgs e)
        {
            byte[] wrong = new byte[1];
            wrong[0] = 0x00;
            port.Write(wrong, 0, wrong.Length);
        }
    }
}

CCS C Code

#include <16f877A.h>

#fuses XT,NOWDT,NOPROTECT,NOBROWNOUT,NOLVP,NOPUT,NOWRT,NODEBUG,NOCPD

#use delay (clock=4000000)

#use rs232 (baud=9600, xmit=pin_c6, rcv=pin_c7, parity=N, stop=1, bits=8)

char received;
char right = 0x01;

#int_rda
void serial_interrupt()
{
   disable_interrupts(int_rda);
   received = getc();
   if(received == right)
   {
      output_high(pin_c5); //green led
      delay_ms(200);
      output_low(pin_c5);
   }
   else
   {
      output_high(pin_c4); //red led
      delay_ms(200);
      output_low(pin_c4);
   }
}

void main()
{
   setup_psp(PSP_DISABLED);
   setup_timer_1(T1_DISABLED);
   setup_timer_2(T2_DISABLED,0,1);
   setup_adc_ports(NO_ANALOGS);
   setup_adc(ADC_OFF);
   setup_CCP1(CCP_OFF);
   setup_CCP2(CCP_OFF);

   output_low(pin_c4);
   output_low(pin_c5);

   enable_interrupts(GLOBAL);
   while(1)
   {
      enable_interrupts(int_rda);
   }
}

Answer 1

If it receives 0x00 in both cases, it is likely that you have a baud rate mismatch, even a slight one. After detecting a start bit, the PIC might be seeing the first 7 zeroes and think it saw 8, going you 0x00 in both cases. I would try transmitting from the PIC and PC and watching the lines on a scope to ensure they are running the same speed. You can also try continuously transmitting 0xAA to get an eye pattern (10101010) and comparing the two signals.