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TheKittyTheKitty
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Create i2c.h
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‎Mini_LED_Gamer/Mini_LED_Gamer/i2c.h‎

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// This library provides the high-level functions needed to use the I2C
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// serial interface supported by the hardware of several AVR processors.
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#ifndef i2c_h
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#define i2c_h
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#include <avr/io.h>
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// TWSR values (status codes)
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// Master
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#define TW_START 0x08
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#define TW_REP_START 0x10
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// Master Transmitter
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#define TW_MT_SLA_ACK 0x18
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#define TW_MT_SLA_NACK 0x20
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#define TW_MT_DATA_ACK 0x28
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#define TW_MT_DATA_NACK 0x30
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#define TW_MT_ARB_LOST 0x38
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// Master Receiver
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#define TW_MR_ARB_LOST 0x38
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#define TW_MR_SLA_ACK 0x40
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#define TW_MR_SLA_NACK 0x48
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#define TW_MR_DATA_ACK 0x50
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#define TW_MR_DATA_NACK 0x58
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// Slave Transmitter
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#define TW_ST_SLA_ACK 0xA8
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#define TW_ST_ARB_LOST_SLA_ACK 0xB0
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#define TW_ST_DATA_ACK 0xB8
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#define TW_ST_DATA_NACK 0xC0
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#define TW_ST_LAST_DATA 0xC8
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// Slave Receiver
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#define TW_SR_SLA_ACK 0x60
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#define TW_SR_ARB_LOST_SLA_ACK 0x68
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#define TW_SR_GCALL_ACK 0x70
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#define TW_SR_ARB_LOST_GCALL_ACK 0x78
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#define TW_SR_DATA_ACK 0x80
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#define TW_SR_DATA_NACK 0x88
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#define TW_SR_GCALL_DATA_ACK 0x90
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#define TW_SR_GCALL_DATA_NACK 0x98
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#define TW_SR_STOP 0xA0
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// Misc
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#define TW_NO_INFO 0xF8
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#define TW_BUS_ERROR 0x00
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// defines and constants
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#define TWCR_CMD_MASK 0x0F
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#define TWSR_STATUS_MASK 0xF8
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// return values
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#define I2C_OK 0x00
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#define I2C_ERROR_NODEV 0x01
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//! Initialize I2C (TWI) interface
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void i2cInit(void);
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// Low-level I2C transaction commands
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//! Send an I2C start condition in Master mode
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void i2cSendStart(void);
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//! Send an I2C stop condition in Master mode
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void i2cSendStop(void);
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//! Wait for current I2C operation to complete
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void i2cWaitForComplete(void);
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//! Send an (address|R/W) combination or a data byte over I2C
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void i2cSendByte(unsigned char data);
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//! Receive a data byte over I2C
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// ackFlag = -1 if recevied data should be ACK'ed
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// ackFlag = 0 if recevied data should be NACK'ed
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void i2cReceiveByte(unsigned char ackFlag);
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//! Pick up the data that was received with i2cReceiveByte()
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unsigned char i2cGetReceivedByte(void);
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//! Get current I2c bus status from TWSR
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unsigned char i2cGetStatus(void);
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void delay_10us(uint16_t x);
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/*********************
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****I2C Functions****
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*********************/
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void i2cInit(void){
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// set SCL freq = F_CPU/(16+2*TWBR*4^TWPS))=16*10^6/(16+2*12)=400kHz
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TWSR &= ~(_BV(TWPS0)|_BV(TWPS1)); // clear TWPS in TWSR register, setting prescaler(TWPS) = 0
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TWBR = 12; // set bit rate register (12 -> 400kHz; 32 -> 200kHz)
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TWCR |= _BV(TWEN); // Enable TWI
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}
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void i2cSendStart(void){
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// send start condition
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TWCR = _BV(TWINT)|_BV(TWSTA)|_BV(TWEN);
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}
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void i2cSendStop(void){
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// transmit stop condition
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TWCR = _BV(TWINT)|_BV(TWEN)|_BV(TWSTO);
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}
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void i2cWaitForComplete(void){
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// wait for i2c interface to complete operation, use i for timeout
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uint8_t i = 0;
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while ((!(TWCR & (1<<TWINT))) && (i < 90))
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i++;
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}
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void i2cSendByte(uint8_t data){
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delay_10us(1);
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TWDR = data; // save data to the TWDR
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TWCR = (1<<TWINT) | (1<<TWEN); // begin send
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}
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void i2cReceiveByte(uint8_t ackFlag){
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if( ackFlag ){
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// ackFlag = 1: ACK the recevied data (would like to receive more data)
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TWCR = (TWCR&TWCR_CMD_MASK)|_BV(TWINT)|_BV(TWEA);
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}
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else{
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// ackFlag = 0: NACK the recevied data (want to stop receiving data)
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TWCR = (TWCR&TWCR_CMD_MASK)|_BV(TWINT);
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}
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}
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unsigned char i2cGetReceivedByte(void) {
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// retieve received data byte from i2c TWDR
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return(TWDR);
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}
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unsigned char i2cGetStatus(void){
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// retieve current i2c status from i2c TWSR
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return(TWSR);
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}
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void delay_10us(uint16_t x){
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for (; x > 0 ; x--){
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for (uint8_t y = 0 ; y < 25; y++){
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asm volatile ("nop");
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}
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}
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}
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/*********************
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****I2C High Level Functions****
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*********************/
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void writeRegister(uint8_t address, uint8_t data){
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i2cSendStart();
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i2cWaitForComplete();
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i2cSendByte((address<<1));
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i2cWaitForComplete();
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i2cSendByte(data);
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i2cWaitForComplete();
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i2cSendStop();
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}
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void writeRegisters(uint8_t address, uint8_t regsiter, uint8_t i, uint16_t *data){
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i2cSendStart();
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i2cWaitForComplete();
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i2cSendByte((address<<1));
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i2cWaitForComplete();
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i2cSendByte(regsiter);
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i2cWaitForComplete();
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for (uint8_t j=0;j<i;j++) {
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i2cSendByte(data[j]&255);
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i2cWaitForComplete();
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i2cSendByte((data[j]>>8)&255);
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i2cWaitForComplete();
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}
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i2cSendStop();
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}
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uint8_t readRegister(uint8_t address, uint8_t regsiter){
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i2cSendStart();
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i2cWaitForComplete();
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i2cSendByte((address<<1));
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i2cWaitForComplete();
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i2cSendByte(regsiter);
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i2cWaitForComplete();
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i2cSendStart();
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i2cWaitForComplete();
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i2cSendByte((address<<1)|0x01);
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i2cWaitForComplete();
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i2cReceiveByte(0);
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i2cWaitForComplete();
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uint8_t data = i2cGetReceivedByte();
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i2cSendStop();
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return data;
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}
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#endif

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