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@@ -1,166 +0,0 @@
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-#include <util/twi.h>
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-#include <avr/io.h>
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-#include <stdlib.h>
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-#include <avr/interrupt.h>
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-#include <util/twi.h>
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-#include <stdbool.h>
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-#include "i2c.h"
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-
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-#ifdef USE_I2C
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-
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-// Limits the amount of we wait for any one i2c transaction.
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-// Since were running SCL line 100kHz (=> 10μs/bit), and each transactions is
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-// 9 bits, a single transaction will take around 90μs to complete.
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-//
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-// (F_CPU/SCL_CLOCK) => # of μC cycles to transfer a bit
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-// poll loop takes at least 8 clock cycles to execute
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-#define I2C_LOOP_TIMEOUT (9+1)*(F_CPU/SCL_CLOCK)/8
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-
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-#define BUFFER_POS_INC() (slave_buffer_pos = (slave_buffer_pos+1)%SLAVE_BUFFER_SIZE)
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-
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-volatile uint8_t i2c_slave_buffer[SLAVE_BUFFER_SIZE];
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-
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-static volatile uint8_t slave_buffer_pos;
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-static volatile bool slave_has_register_set = false;
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-
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-// Wait for an i2c operation to finish
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-inline static
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-void i2c_delay(void) {
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- uint16_t lim = 0;
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- while(!(TWCR & (1<<TWINT)) && lim < I2C_LOOP_TIMEOUT)
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- lim++;
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-
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- // easier way, but will wait slightly longer
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- // _delay_us(100);
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-}
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-
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-// Setup twi to run at 100kHz
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-void i2c_master_init(void) {
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- // no prescaler
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- TWSR = 0;
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- // Set TWI clock frequency to SCL_CLOCK. Need TWBR>10.
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- // Check datasheets for more info.
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- TWBR = ((F_CPU/SCL_CLOCK)-16)/2;
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-}
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-
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-// Start a transaction with the given i2c slave address. The direction of the
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-// transfer is set with I2C_READ and I2C_WRITE.
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-// returns: 0 => success
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-// 1 => error
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-uint8_t i2c_master_start(uint8_t address) {
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- TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN);
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-
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- i2c_delay();
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-
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- // check that we started successfully
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- if ( (TW_STATUS != TW_START) && (TW_STATUS != TW_REP_START))
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- return 1;
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-
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- // send device address
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- TWDR = address;
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- TWCR = (1<<TWINT) | (1<<TWEN);
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-
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- i2c_delay();
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-
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- if ( (TW_STATUS != TW_MT_SLA_ACK) && (TW_STATUS != TW_MR_SLA_ACK) )
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- return 1; // slave did not acknowledge
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- else
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- return 0; // success
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-}
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-
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-
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-// Finish the i2c transaction.
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-void i2c_master_stop(void) {
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- TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);
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-
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- uint16_t lim = 0;
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- while(!(TWCR & (1<<TWSTO)) && lim < I2C_LOOP_TIMEOUT)
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- lim++;
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-}
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-
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-// Write one byte to the i2c slave.
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-// returns 0 => slave ACK
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-// 1 => slave NACK
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-uint8_t i2c_master_write(uint8_t data) {
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- TWDR = data;
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- TWCR = (1<<TWINT) | (1<<TWEN);
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-
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- i2c_delay();
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-
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- // check if the slave acknowledged us
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- return (TW_STATUS == TW_MT_DATA_ACK) ? 0 : 1;
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-}
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-
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-// Read one byte from the i2c slave. If ack=1 the slave is acknowledged,
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-// if ack=0 the acknowledge bit is not set.
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-// returns: byte read from i2c device
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-uint8_t i2c_master_read(int ack) {
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- TWCR = (1<<TWINT) | (1<<TWEN) | (ack<<TWEA);
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-
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- i2c_delay();
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- return TWDR;
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-}
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-
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-void i2c_reset_state(void) {
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- TWCR = 0;
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-}
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-
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-void i2c_slave_init(uint8_t address) {
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- TWAR = address << 0; // slave i2c address
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- // TWEN - twi enable
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- // TWEA - enable address acknowledgement
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- // TWINT - twi interrupt flag
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- // TWIE - enable the twi interrupt
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- TWCR = (1<<TWIE) | (1<<TWEA) | (1<<TWINT) | (1<<TWEN);
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-}
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-
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-ISR(TWI_vect);
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-
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-ISR(TWI_vect) {
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- uint8_t ack = 1;
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- switch(TW_STATUS) {
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- case TW_SR_SLA_ACK:
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- // this device has been addressed as a slave receiver
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- slave_has_register_set = false;
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- break;
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-
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- case TW_SR_DATA_ACK:
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- // this device has received data as a slave receiver
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- // The first byte that we receive in this transaction sets the location
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- // of the read/write location of the slaves memory that it exposes over
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- // i2c. After that, bytes will be written at slave_buffer_pos, incrementing
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- // slave_buffer_pos after each write.
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- if(!slave_has_register_set) {
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- slave_buffer_pos = TWDR;
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- // don't acknowledge the master if this memory loctaion is out of bounds
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- if ( slave_buffer_pos >= SLAVE_BUFFER_SIZE ) {
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- ack = 0;
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- slave_buffer_pos = 0;
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- }
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- slave_has_register_set = true;
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- } else {
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- i2c_slave_buffer[slave_buffer_pos] = TWDR;
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- BUFFER_POS_INC();
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- }
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- break;
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-
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- case TW_ST_SLA_ACK:
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- case TW_ST_DATA_ACK:
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- // master has addressed this device as a slave transmitter and is
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- // requesting data.
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- TWDR = i2c_slave_buffer[slave_buffer_pos];
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- BUFFER_POS_INC();
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- break;
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-
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- case TW_BUS_ERROR: // something went wrong, reset twi state
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- TWCR = 0;
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- default:
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- break;
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- }
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- // Reset everything, so we are ready for the next TWI interrupt
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- TWCR |= (1<<TWIE) | (1<<TWINT) | (ack<<TWEA) | (1<<TWEN);
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-}
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-
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-
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-
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-#endif
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TerryMathews