72 lines
2.3 KiB
C
72 lines
2.3 KiB
C
#pragma once
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#include <avr/io.h>
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// control bits
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// source: https://www.exploreembedded.com/wiki/Basics_of_I2C_with_AVR
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#define INTERRUPT_CB TWINT
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#define ENABLE_ACK_CB TWEA
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#define START_CONDITION_CB TWSTA
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#define STOP_CONDITION_CB TWSTO
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#define WRITE_COLLISION_CB TWWC
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#define TWI_ENABLE_CB TWEN
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#define INTERRUPT_ENABLE_CB TWIE
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#define START_COND_CB START_CONDITION_CB
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#define STOP_COND_CB STOP_COND_CB
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// status bits
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// source: https://www.microchip.com/webdoc/AVRLibcReferenceManual/ch20s33s01.html
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// registers
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#define BIT_RATE_REG TWBR
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#define CONTROL_REG TWCR
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#define DATA_REG TWDR
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#define STATUS_REG TWSR
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#define ENABLE_REG TWEN
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#define MASTER_REG TWSTA
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#define STOP_COND_REG TWSTO
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// misc constants
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#define TWI_READ 1
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#define TWI_WRITE 0
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#define PRESCALAR_MASK 0xF8 // I don't know where this comes from T_T
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#define SCL_CLOCK_100_MHZ 100000L // TODO: which resistor?
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#define SCL_CLOCK_400_MHZ 400000L // TODO: which resistor?
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#define SCL_CLOCK_1700_MHZ 1700000L // TODO: which resistor?
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// helpers
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#define WAIT_FOR_CONTROL_FLAGS(FLAGS) while(!(CONTROL_REG & FLAGS));
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#define WAIT_FOR_INTERRUPT WAIT_FOR_CONTROL_FLAGS(S1(INTERRUPT_CB))
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#define WAIT_FOR_START WAIT_FOR_CONTROL_FLAGS(S1(START_CONDITION_CB))
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#define WAIT_FOR_STOP WAIT_FOR_CONTROL_FLAGS(S1(STOP_CONDITION_CB))
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#define CURRENT_STATUS (TW_STATUS & PRESCALAR_MASK)
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extern void twi_init(void);
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extern void twi_stop(void);
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extern unsigned char twi_start(unsigned char addr);
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extern unsigned char twi_rep_start(unsigned char addr);
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extern void twi_start_wait(unsigned char addr);
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extern unsigned char twi_write(unsigned char data);
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extern unsigned char twi_read_ack(void);
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extern unsigned char twi_read_nak(void);
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extern unsigned char twi_read(unsigned char ack);
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#define twi_read(ack) (ack) ? twi_readAck() : twi_readNak();
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/*
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modified from Peter Fleury's code
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found at /keyboards/ergodone/twimaster.h
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original header below
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*/
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/*************************************************************************
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* Title: C include file for the I2C master interface
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* (i2cmaster.S or twimaster.c)
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* Author: Peter Fleury <pfleury@gmx.ch> http://jump.to/fleury
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* File: $Id: i2cmaster.h,v 1.10 2005/03/06 22:39:57 Peter Exp $
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* Software: AVR-GCC 3.4.3 / avr-libc 1.2.3
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* Target: any AVR device
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* Usage: see Doxygen manual
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**************************************************************************/
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