60 lines
1.1 KiB
C
60 lines
1.1 KiB
C
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/*
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* i2c.h
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*
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* Created: 5/21/2014 11:41:32 PM
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* Author: true
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*/
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#ifndef I2C_H_
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#define I2C_H_
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#include "config.h"
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/* macros */
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#define i2c_clear_int_flag() TWCR |= _BV(TWINT)
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#define i2c_disable_interrupt() TWCR &= ~(_BV(TWIE))
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#define i2c_enable_interrupt() TWCR |= _BV(TWIE)
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#define i2c_disable_slave() TWCR &= ~(_BV(TWEA))
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#define i2c_enable_slave() TWCR |= _BV(TWEA)
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/* configuration */
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static inline void i2c_slave_init(uint8_t address, uint8_t enable_general_addr)
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{
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// set bitrate register, clear prescaler
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// should get us 400KHz (fast mode) max rate
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TWBR = 2;
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TWSR = ~(_BV(TWPS0) | _BV(TWPS1));
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// set slave address and clear address mask
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TWAR = ((address << 1) | (enable_general_addr & 1));
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TWAMR = 0;
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// enable auto-ack, enable TWI, and enable the TWI interrupt
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TWCR = _BV(TWEA) | _BV(TWEN) | _BV(TWIE);
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}
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/* sending */
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static uint8_t i2c_slave_tx(uint8_t byte, uint8_t is_last_byte)
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{
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// load data
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TWDR = byte;
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// start sending
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TWCR |= _BV(TWINT);
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if (is_last_byte) {
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// this is all the data we have to send; send a nack after this byte
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i2c_disable_slave();
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}
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return 0;
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}
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#endif /* I2C_H_ */
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