82 lines
3.3 KiB
C
82 lines
3.3 KiB
C
/*
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* TWIlib.h
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*
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* Created: 6/01/2014 10:38:42 PM
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* Author: Chris Herring
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* http://www.chrisherring.net/all/tutorial-interrupt-driven-twi-interface-for-avr-part1/
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*/
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#ifndef TWILIB_H_
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#define TWILIB_H_
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// TWI bit rate (was 100000)
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#define TWI_FREQ 400000
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// Get TWI status
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#define TWI_STATUS (TWSR & 0xF8)
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// Transmit buffer length
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#define TXMAXBUFLEN 20
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// Receive buffer length
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#define RXMAXBUFLEN 20
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// Global transmit buffer
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uint8_t TWITransmitBuffer[TXMAXBUFLEN];
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// Global receive buffer
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volatile uint8_t TWIReceiveBuffer[RXMAXBUFLEN];
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// Buffer indexes
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volatile int TXBuffIndex; // Index of the transmit buffer. Is volatile, can change at any time.
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int RXBuffIndex; // Current index in the receive buffer
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// Buffer lengths
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int TXBuffLen; // The total length of the transmit buffer
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int RXBuffLen; // The total number of bytes to read (should be less than RXMAXBUFFLEN)
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typedef enum {
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Ready,
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Initializing,
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RepeatedStartSent,
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MasterTransmitter,
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MasterReceiver,
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SlaceTransmitter,
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SlaveReciever
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} TWIMode;
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typedef struct TWIInfoStruct{
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TWIMode mode;
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uint8_t errorCode;
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uint8_t repStart;
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}TWIInfoStruct;
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TWIInfoStruct TWIInfo;
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// TWI Status Codes
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#define TWI_START_SENT 0x08 // Start sent
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#define TWI_REP_START_SENT 0x10 // Repeated Start sent
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// Master Transmitter Mode
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#define TWI_MT_SLAW_ACK 0x18 // SLA+W sent and ACK received
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#define TWI_MT_SLAW_NACK 0x20 // SLA+W sent and NACK received
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#define TWI_MT_DATA_ACK 0x28 // DATA sent and ACK received
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#define TWI_MT_DATA_NACK 0x30 // DATA sent and NACK received
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// Master Receiver Mode
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#define TWI_MR_SLAR_ACK 0x40 // SLA+R sent, ACK received
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#define TWI_MR_SLAR_NACK 0x48 // SLA+R sent, NACK received
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#define TWI_MR_DATA_ACK 0x50 // Data received, ACK returned
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#define TWI_MR_DATA_NACK 0x58 // Data received, NACK returned
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// Miscellaneous States
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#define TWI_LOST_ARBIT 0x38 // Arbitration has been lost
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#define TWI_NO_RELEVANT_INFO 0xF8 // No relevant information available
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#define TWI_ILLEGAL_START_STOP 0x00 // Illegal START or STOP condition has been detected
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#define TWI_SUCCESS 0xFF // Successful transfer, this state is impossible from TWSR as bit2 is 0 and read only
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#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.
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#define TWISendStop() (TWCR = (1<<TWINT)|(1<<TWSTO)|(1<<TWEN)|(1<<TWIE)) // Send the STOP signal, enable interrupts and TWI, clear TWINT flag.
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#define TWISendTransmit() (TWCR = (1<<TWINT)|(1<<TWEN)|(1<<TWIE)) // Used to resume a transfer, clear TWINT and ensure that TWI and interrupts are enabled.
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#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.
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#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.
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// Function declarations
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uint8_t TWITransmitData(void *const TXdata, uint8_t dataLen, uint8_t repStart);
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void TWIInit(void);
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uint8_t TWIReadData(uint8_t TWIaddr, uint8_t bytesToRead, uint8_t repStart);
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uint8_t isTWIReady(void);
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#endif // TWICOMMS_H_
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