+++ /dev/null
-/*************************************************************************
-* 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 <i2cmaster.h>
-
-
-/* define CPU frequency in Mhz here if not defined in Makefile */
-#ifndef F_CPU
-#define F_CPU 16000000UL
-#endif
-
-/* I2C clock in Hz */
-#define SCL_CLOCK 400000L
-
-
-/*************************************************************************
- Initialization of the I2C bus interface. Need to be called only once
-*************************************************************************/
-void i2c_init(void)
-{
- /* initialize TWI clock
- * minimal values in Bit Rate Register (TWBR) and minimal Prescaler
- * bits in the TWI Status Register should give us maximal possible
- * I2C bus speed - about 444 kHz
- *
- * for more details, see 20.5.2 in ATmega16/32 secification
- */
-
- TWSR = 0; /* no prescaler */
- TWBR = 10; /* 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
- 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)) return 1;
-
- // send device address
- TWDR = address;
- TWCR = (1<<TWINT) | (1<<TWEN);
-
- // wail until transmission completed and ACK/NACK has been received
- while(!(TWCR & (1<<TWINT)));
-
- // 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
- while(TWCR & (1<<TWSTO));
-
- 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
- while(TWCR & (1<<TWSTO));
-
-}/* 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
- while(!(TWCR & (1<<TWINT)));
-
- // 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);
- while(!(TWCR & (1<<TWINT)));
-
- 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);
- while(!(TWCR & (1<<TWINT)));
-
- return TWDR;
-
-}/* i2c_readNak */
projects / qmk_firmware.git / blobdiff