#include<reg51f.h>
#include<stdio.h>
#include<string.h>
#define BAUD_RATE 9600.0
#define IN_BUF_SIZE 256
#define TRUE 1
#define FALSE 0
#define port P0
#define lcdport P1 //14,13,12,11 pins of lcd and 1.7,1.6,1.5,1.4 of controller
sbit rs=port^0; //Register select
sbit rw=port^1; //Read/Write
sbit en=port^2; //Enable pin
static unsigned char inbuf[IN_BUF_SIZE];
static unsigned char qin;
static unsigned char qout;
static char flag_rx_waiting_for_stop_bit;
static char flag_rx_off;
static char rx_mask;
static char flag_rx_ready;
static char flag_tx_ready;
static char timer_rx_ctr;
static char timer_tx_ctr;
static char bits_left_in_rx;
static char bits_left_in_tx;
static char rx_num_of_bits;
static char tx_num_of_bits;
static char internal_rx_buffer;
static char internal_tx_buffer;
static char user_tx_buffer;
sbit rx_pin=P2^0;
sbit tx_pin=P2^1;
char ch=0;
void delay(unsigned int count) //Function to provide delay
{
int i,j;
for(i=0;i<count;i++)
for(j=0;j<1100;j++);
}
/**************************** START OF LCD FUNCTIONS ***********************/
void lcdcmd(char cmdout)
{
lcdport=cmdout;
rs=0;
rw=0;
en=1;
delay(10);
en=0;
}
void lcddata(char dataout)
{
lcdport=dataout;
rs=1;
rw=0;
en=1;
delay(10);
en=0;
}
void dis_cmd(char cmd_value)
{
char cmd_value1;
cmd_value1 = cmd_value & 0xF0; //mask lower nibble because PA4-PA7 pins are used.
lcdcmd(cmd_value1); // send to LCD
cmd_value1 = ((cmd_value<<4) & 0xF0); //shift 4-bit and mask
lcdcmd(cmd_value1); // send to LCD
}
void dis_data(char data_value)
{
char data_value1;
data_value1=data_value&0xF0;
lcddata(data_value1);
data_value1=((data_value<<4)&0xF0);
lcddata(data_value1);
}
void lcd_init() // fuction for intialize
{
dis_cmd(0x02); // to initialize LCD in 4-bit mode.
dis_cmd(0x28); //to initialize LCD in 2 lines, 5X7 dots and 4bit mode.
dis_cmd(0x0C);
dis_cmd(0x06);
dis_cmd(0x80);
}
/************************ END OF LCD FUNCTIONS **************************/
char get_rx_pin_status(void) //Returns 0 or 1 dependent on whether the receive pin is high or low.
{
if(rx_pin==1)
{
return 0;
}
else
return 1;
}
void set_tx_pin_high(void) // Sets the transmit pin to the high state.
{
tx_pin=1;
}
void set_tx_pin_low(void) // Sets the transmit pin to the low state.
{
tx_pin=0;
}
void idle(void) // Background functions to execute while waiting for input.
{
unsigned char i=0,data0[]="idle";
dis_cmd(0xC1);
while(data0[i]!='\0')
{
dis_data(data0[i]);
delay(20);
i++;
}
}
void timer_set( ) // Sets the timer to 3 times the baud rate.
{
T2CON = 0x04; // Load Timer 2 control register
TH2 = 0xFF; // Load Timer 2 high byte
RCAP2H = 0xFF; // Load Timer 2 reload capt. reg. high byte
TL2 = 0xE0; // Load Timer 2 low byte
RCAP2L = 0xE0; // Load Timer 2 reload capt. reg. low byte
//Disable Interrupt Service Routine
//ET2 = 0;
//TR2 = 0;
}
void timer_isr(void) interrupt 5
{
char mask,start_bit, flag_in;
// Transmitter Section
if ( flag_tx_ready )
{
if ( --timer_tx_ctr<=0 )
{
mask = internal_tx_buffer&1;
internal_tx_buffer >>= 1;
if ( mask )
{
set_tx_pin_high();
}
else
{
set_tx_pin_low();
dis_cmd(0x80);
dis_data(48);
}
timer_tx_ctr = 3;
if ( --bits_left_in_tx<=0 )
{
flag_tx_ready = FALSE;
}
}
}
// Receiver Section
if ( flag_rx_off==FALSE )
{
if ( flag_rx_waiting_for_stop_bit )
{
if ( --timer_rx_ctr<=0 )
{
flag_rx_waiting_for_stop_bit = FALSE;
flag_rx_ready = FALSE;
internal_rx_buffer &= 0xFF;
if ( internal_rx_buffer!=0xC2 )
{
inbuf[qin] = internal_rx_buffer;
qin++;
dis_cmd(0x80);
dis_data(53);
if ( ++qin>=IN_BUF_SIZE )
{
qin = 0;
}
}
}
}
else // rx_test_busy
{
if ( flag_rx_ready==FALSE )
{
start_bit = get_rx_pin_status();
// Test for Start Bit
if ( start_bit==0 )
{
flag_rx_ready = TRUE;
internal_rx_buffer = 0;
timer_rx_ctr = 4;
bits_left_in_rx = rx_num_of_bits;
rx_mask = 1;
}
}
else // rx_busy
{
if ( --timer_rx_ctr<=0 )
{ // rcv
timer_rx_ctr = 3;
flag_in = get_rx_pin_status();
if ( flag_in )
{
internal_rx_buffer |= rx_mask;
}
rx_mask <<= 1;
if ( --bits_left_in_rx<=0 )
{
flag_rx_waiting_for_stop_bit = TRUE;
}
}
}
}
}
}
void set_timer_interrupt(timer_isr) // Enables the timer interrupt.
{
EA=1;
ET2 =1;
TR2 =1;
}
char _getchar( void )
{
do
{
while ( qout==qin )
{
idle();
}
ch = inbuf[qout]& 0xFF;
dis_cmd(0xC1);
dis_data(ch);
if ( ++qout>=IN_BUF_SIZE )
{
qout = 0;
}
}
while ( ch==0x0A || ch==0xC2 );
return( ch );
}
/*void _putchar(char ch )
{
while ( flag_tx_ready );
user_tx_buffer = ch;
// invoke_UART_transmit
timer_tx_ctr = 3;
bits_left_in_tx = tx_num_of_bits;
internal_tx_buffer = (user_tx_buffer<<1) | 0x200;
flag_tx_ready = TRUE;
}*/
void send(char ch)
{
while ( flag_tx_ready );
user_tx_buffer = ch;
// invoke_UART_transmit
timer_tx_ctr = 3;
bits_left_in_tx = tx_num_of_bits;
internal_tx_buffer = (user_tx_buffer<<1) | 0x200;
flag_tx_ready = TRUE;
}
void flush_input_buffer( void )
{
inbuf[IN_BUF_SIZE]=0;
//qin = 0;
//qout = 0;
}
char kbhit( void )
{
return( qin!=qout );
}
void turn_rx_on( void )
{
flag_rx_off = FALSE;
}
void turn_rx_off( void )
{
flag_rx_off = TRUE;
}
void init_uart( void )
{
flag_tx_ready = FALSE;
flag_rx_ready = FALSE;
flag_rx_waiting_for_stop_bit = FALSE;
flag_rx_off = FALSE;
rx_num_of_bits = 10;
tx_num_of_bits = 10;
set_tx_pin_low();
timer_set();
set_timer_interrupt(timer_isr); // Enable timer interrupt
}
void main()
{
char a,l=0;
P2=0x00;
//ch=0;
lcdport=0;
lcd_init();
dis_cmd(0x01);
init_uart();
turn_rx_on();
while(1)
{
a=kbhit();
if(a==1)
{
_getchar();
}
}
}