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/*
* TWIlib.h
*
* Created: 6/01/2014 10:38:42 PM
* Author: Chris Herring
* http://www.chrisherring.net/all/tutorial-interrupt-driven-twi-interface-for-avr-part1/
*/
#ifndef TWILIB_H_
#define TWILIB_H_
// TWI bit rate (was 100000)
#define TWI_FREQ 400000
// Get TWI status
#define TWI_STATUS (TWSR & 0xF8)
// Transmit buffer length
#define TXMAXBUFLEN 20
// Receive buffer length
#define RXMAXBUFLEN 20
// Global transmit buffer
uint8_t TWITransmitBuffer[TXMAXBUFLEN];
// Global receive buffer
volatile uint8_t TWIReceiveBuffer[RXMAXBUFLEN];
// Buffer indexes
volatile int TXBuffIndex; // Index of the transmit buffer. Is volatile, can change at any time.
int RXBuffIndex; // Current index in the receive buffer
// Buffer lengths
int TXBuffLen; // The total length of the transmit buffer
int RXBuffLen; // The total number of bytes to read (should be less than RXMAXBUFFLEN)
typedef enum {
Ready,
Initializing,
RepeatedStartSent,
MasterTransmitter,
MasterReceiver,
SlaceTransmitter,
SlaveReciever
} TWIMode;
typedef struct TWIInfoStruct{
TWIMode mode;
uint8_t errorCode;
uint8_t repStart;
}TWIInfoStruct;
TWIInfoStruct TWIInfo;
// TWI Status Codes
#define TWI_START_SENT 0x08 // Start sent
#define TWI_REP_START_SENT 0x10 // Repeated Start sent
// Master Transmitter Mode
#define TWI_MT_SLAW_ACK 0x18 // SLA+W sent and ACK received
#define TWI_MT_SLAW_NACK 0x20 // SLA+W sent and NACK received
#define TWI_MT_DATA_ACK 0x28 // DATA sent and ACK received
#define TWI_MT_DATA_NACK 0x30 // DATA sent and NACK received
// Master Receiver Mode
#define TWI_MR_SLAR_ACK 0x40 // SLA+R sent, ACK received
#define TWI_MR_SLAR_NACK 0x48 // SLA+R sent, NACK received
#define TWI_MR_DATA_ACK 0x50 // Data received, ACK returned
#define TWI_MR_DATA_NACK 0x58 // Data received, NACK returned
// Miscellaneous States
#define TWI_LOST_ARBIT 0x38 // Arbitration has been lost
#define TWI_NO_RELEVANT_INFO 0xF8 // No relevant information available
#define TWI_ILLEGAL_START_STOP 0x00 // Illegal START or STOP condition has been detected
#define TWI_SUCCESS 0xFF // Successful transfer, this state is impossible from TWSR as bit2 is 0 and read only
#define TWISendStart() (TWCR = (1<<TWINT)|(1<<TWSTA)|(1<<TWEN)|(1<<TWIE)) // Send the START signal, enable interrupts and TWI, clear TWINT flag to resume transfer.
#define TWISendStop() (TWCR = (1<<TWINT)|(1<<TWSTO)|(1<<TWEN)|(1<<TWIE)) // Send the STOP signal, enable interrupts and TWI, clear TWINT flag.
#define TWISendTransmit() (TWCR = (1<<TWINT)|(1<<TWEN)|(1<<TWIE)) // Used to resume a transfer, clear TWINT and ensure that TWI and interrupts are enabled.
#define TWISendACK() (TWCR = (1<<TWINT)|(1<<TWEN)|(1<<TWIE)|(1<<TWEA)) // FOR MR mode. Resume a transfer, ensure that TWI and interrupts are enabled and respond with an ACK if the device is addressed as a slave or after it receives a byte.
#define TWISendNACK() (TWCR = (1<<TWINT)|(1<<TWEN)|(1<<TWIE)) // FOR MR mode. Resume a transfer, ensure that TWI and interrupts are enabled but DO NOT respond with an ACK if the device is addressed as a slave or after it receives a byte.
// Function declarations
uint8_t TWITransmitData(void *const TXdata, uint8_t dataLen, uint8_t repStart);
void TWIInit(void);
uint8_t TWIReadData(uint8_t TWIaddr, uint8_t bytesToRead, uint8_t repStart);
uint8_t isTWIReady(void);
#endif // TWICOMMS_H_
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