1
0
This repo is archived. You can view files and clone it, but cannot push or open issues or pull requests.
tmk_keyboard_custom/keyboard/ergodone/twimaster.c
2016-08-25 18:27:47 +09:00

259 lines
7.4 KiB
C

/*************************************************************************
* Title: I2C master library using hardware TWI interface
* Author: Peter Fleury <pfleury@gmx.ch> http://jump.to/fleury
* File: $Id: twimaster.c,v 1.3 2005/07/02 11:14:21 Peter Exp $
* Software: AVR-GCC 3.4.3 / avr-libc 1.2.3
* Target: any AVR device with hardware TWI
* Usage: API compatible with I2C Software Library i2cmaster.h
**************************************************************************/
#include <inttypes.h>
#include <compat/twi.h>
#include <util/delay.h>
#include <i2cmaster.h>
#include "timer.h"
#include "debug.h"
/* define CPU frequency in Mhz here if not defined in Makefile */
#ifndef F_CPU
#define F_CPU 4000000UL
#endif
/* I2C clock in Hz */
#define SCL_CLOCK 400000L
#define SCL_DURATION (1000000L/SCL_CLOCK)/2
volatile uint8_t i2c_force_stop = 0;
#define TIMEOUT 3000
#define CHECK_FORCE_STOP() if(i2c_force_stop){i2c_force_stop=0;break;}
#define CHECK_TIMEOUT_PRE() \
uint16_t start; \
uint8_t once = 1;
#define CHECK_TIMEOUT_PRE2() \
once = 1;
#define CHECK_TIMEOUT(retval) { \
if (once) { \
start = timer_read(); \
once = 0; \
} \
else { \
if (timer_elapsed(start) >= TIMEOUT) { \
i2c_forceStop(); \
return retval; \
} \
} \
}
static void i2c_forceStop(void);
/*************************************************************************
Initialization of the I2C bus interface. Need to be called only once
*************************************************************************/
void i2c_init(void)
{
/* initialize TWI clock: 100 kHz clock, TWPS = 0 => prescaler = 1 */
TWSR = 0; /* no prescaler */
TWBR = ((F_CPU/SCL_CLOCK)-16)/2; /* must be > 10 for stable operation */
}/* i2c_init */
/*************************************************************************
Issues a start condition and sends address and transfer direction.
return 0 = device accessible, 1= failed to access device
*************************************************************************/
unsigned char i2c_start(unsigned char address)
{
uint8_t twst;
// send START condition
TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN);
// wait until transmission completed
CHECK_TIMEOUT_PRE();
while(!(TWCR & (1<<TWINT))) { CHECK_TIMEOUT(2); };
// check value of TWI Status Register. Mask prescaler bits.
twst = TW_STATUS & 0xF8;
if ( (twst != TW_START) && (twst != TW_REP_START)) return 1;
// send device address
TWDR = address;
TWCR = (1<<TWINT) | (1<<TWEN);
// wail until transmission completed and ACK/NACK has been received
CHECK_TIMEOUT_PRE2();
while(!(TWCR & (1<<TWINT))) { CHECK_TIMEOUT(2); };
// check value of TWI Status Register. Mask prescaler bits.
twst = TW_STATUS & 0xF8;
if ( (twst != TW_MT_SLA_ACK) && (twst != TW_MR_SLA_ACK) ) return 1;
return 0;
}/* i2c_start */
/*************************************************************************
Issues a start condition and sends address and transfer direction.
If device is busy, use ack polling to wait until device is ready
Input: address and transfer direction of I2C device
*************************************************************************/
void i2c_start_wait(unsigned char address)
{
uint8_t twst;
while ( 1 )
{
// send START condition
TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN);
// wait until transmission completed
while(!(TWCR & (1<<TWINT)));
// check value of TWI Status Register. Mask prescaler bits.
twst = TW_STATUS & 0xF8;
if ( (twst != TW_START) && (twst != TW_REP_START)) continue;
// send device address
TWDR = address;
TWCR = (1<<TWINT) | (1<<TWEN);
// wail until transmission completed
while(!(TWCR & (1<<TWINT)));
// check value of TWI Status Register. Mask prescaler bits.
twst = TW_STATUS & 0xF8;
if ( (twst == TW_MT_SLA_NACK )||(twst ==TW_MR_DATA_NACK) )
{
/* device busy, send stop condition to terminate write operation */
TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);
// wait until stop condition is executed and bus released
CHECK_TIMEOUT_PRE();
while(TWCR & (1<<TWSTO)) { CHECK_TIMEOUT(); };
continue;
}
//if( twst != TW_MT_SLA_ACK) return 1;
break;
}
}/* i2c_start_wait */
/*************************************************************************
Issues a repeated start condition and sends address and transfer direction
Input: address and transfer direction of I2C device
Return: 0 device accessible
1 failed to access device
*************************************************************************/
unsigned char i2c_rep_start(unsigned char address)
{
return i2c_start( address );
}/* i2c_rep_start */
/*************************************************************************
Terminates the data transfer and releases the I2C bus
*************************************************************************/
void i2c_stop(void)
{
/* send stop condition */
TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);
// wait until stop condition is executed and bus released
CHECK_TIMEOUT_PRE();
while(TWCR & (1<<TWSTO)) { CHECK_TIMEOUT(); };
}/* i2c_stop */
/*************************************************************************
Send one byte to I2C device
Input: byte to be transfered
Return: 0 write successful
1 write failed
*************************************************************************/
unsigned char i2c_write( unsigned char data )
{
uint8_t twst;
// send data to the previously addressed device
TWDR = data;
TWCR = (1<<TWINT) | (1<<TWEN);
// wait until transmission completed
CHECK_TIMEOUT_PRE();
while(!(TWCR & (1<<TWINT))) { CHECK_TIMEOUT(2) };
// check value of TWI Status Register. Mask prescaler bits
twst = TW_STATUS & 0xF8;
if( twst != TW_MT_DATA_ACK) return 1;
return 0;
}/* i2c_write */
/*************************************************************************
Read one byte from the I2C device, request more data from device
Return: byte read from I2C device
*************************************************************************/
unsigned char i2c_readAck(void)
{
TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWEA);
CHECK_TIMEOUT_PRE();
while(!(TWCR & (1<<TWINT))) { CHECK_TIMEOUT(2); };
return TWDR;
}/* i2c_readAck */
/*************************************************************************
Read one byte from the I2C device, read is followed by a stop condition
Return: byte read from I2C device
*************************************************************************/
unsigned char i2c_readNak(void)
{
TWCR = (1<<TWINT) | (1<<TWEN);
CHECK_TIMEOUT_PRE();
while(!(TWCR & (1<<TWINT))) { CHECK_TIMEOUT(2); };
return TWDR;
}/* i2c_readNak */
void i2c_forceStop(void)
{
xprintf("i2c timeout\n");
/* let slave to release SDA */
TWCR = 0;
DDRD |= (1<<PD0);
DDRD &= ~(1<<PD1);
_delay_us(30);
if ((PIND & (1<<PD1)) == 0) {
for (uint8_t i = 0; i < 9; i++) {
PORTD &= ~(1<<PD0);
_delay_us(SCL_DURATION);
PORTD |= (1<<PD0);
_delay_us(SCL_DURATION);
}
}
DDRD &= ~(1<<PD0);
/* send stop condition */
TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);
}