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/*
* Soft_UART_Timer1.h
*
* Software UART for ATmega328p using Timer1
*
* Now only tranmission, no receiving
*/
#ifndef SOFTUARTTIMER1_H_
#define SOFTUARTTIMER1_H_
//////////////////////////////////////////////////////////////////////////
// Usage (in your .c file):
// 1. define Tx pin: DDR register, PORT register, PIN number:
// #define Soft_UART_TX_PORT PORTD
// #define Soft_UART_TX_DDR DDRD
// #define Soft_UART_TX_PIN 3
// 2. define UART speed
// #define Soft_UART_Baud 9600
// 3. include .h file:
// #include "Soft_UART_Timer1.h"
// 3. initialize software UART, required to call before usage other functions:
// static void Soft_UART_init(void);
// 4. send byte
// static void Soft_UART_send_byte(char byte);
// this function send byte in background,
// only one byte in background, other will wait.
//////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////
// From this line begins code to the end of file.
// All code written in .h file for better inline optimization.
// Try to include this file only once per project.
//////////////////////////////////////////////////////////////////////////
volatile char Soft_UART_busy_flag=0;
char Soft_UART_next_byte=0;
//////////////////////////////////////////////////////////////////////////
// Initialization software UART, required to call before usage
//////////////////////////////////////////////////////////////////////////
static void Soft_UART_init(void)
{ // Pin init
bit_set(Soft_UART_TX_DDR,Soft_UART_TX_PIN);
bit_set(Soft_UART_TX_PORT,Soft_UART_TX_PIN);
// Timer1 init
TCCR1A=(0<<COM1A1)|(0<<COM1A0)|(0<<COM1B1)|(0<<COM1B0)|(1<<WGM11)|(0<<WGM10);
TCCR1B=(0<<ICNC1)|(0<<ICES1)|(1<<WGM13)|(1<<WGM12)|(0<<CS12)|(0<<CS11)|(0<<CS10); // prescaler 0, timer stopped
TCCR1C=(0<<FOC1A)|(0<<FOC1B);
TIMSK1=(0<<ICIE1)|(0<<OCIE1B)|(0<<OCIE1A)|(0<<TOIE1);
//ICR1=1666;
ICR1=F_CPU/Soft_UART_Baud;
}
//////////////////////////////////////////////////////////////////////////
// Internal function, start timer, when need to send something
//////////////////////////////////////////////////////////////////////////
static void Soft_UART_Timer1_start(void)
{
bit_set(TIMSK1,TOIE1);
bit_set(TCCR1B,CS10);
}
//////////////////////////////////////////////////////////////////////////
// Internal function, stop timer, when nothing to send
//////////////////////////////////////////////////////////////////////////
static void Soft_UART_Timer1_stop(void)
{
bit_clr(TIMSK1,TOIE1);
bit_clr(TCCR1B,CS10);
}
//////////////////////////////////////////////////////////////////////////
// Send byte in background, only one byte in background, other - wait
//////////////////////////////////////////////////////////////////////////
static void Soft_UART_send_byte(char byte)
{
while(Soft_UART_busy_flag)
;
Soft_UART_busy_flag=1;
Soft_UART_Timer1_start();
Soft_UART_next_byte=byte;
}
//////////////////////////////////////////////////////////////////////////
// Internal function, send next bit
//////////////////////////////////////////////////////////////////////////
ISR(TIMER1_OVF_vect)
{
static char Soft_UART_pos=0;
switch(Soft_UART_pos)
{
case 0: // send START bit
bit_clr(Soft_UART_TX_PORT,Soft_UART_TX_PIN);
break;
case 9: // send STOP bit
bit_set(Soft_UART_TX_PORT,Soft_UART_TX_PIN);
break;
case 10:// end of transmission
Soft_UART_busy_flag=0;
Soft_UART_pos=0;
Soft_UART_Timer1_stop();
return;
default:// send data bit
if(bit_tst(Soft_UART_next_byte,Soft_UART_pos-1))
bit_set(Soft_UART_TX_PORT,Soft_UART_TX_PIN);
else
bit_clr(Soft_UART_TX_PORT,Soft_UART_TX_PIN);
break;
}
Soft_UART_pos++;
bit_change(PORTB,5);
}
#endif /* SOFTUARTTIMER1_H_ */
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