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Diffstat (limited to 'drivers/avr/TWIlib.h')
| -rw-r--r-- | drivers/avr/TWIlib.h | 82 |
1 files changed, 82 insertions, 0 deletions
diff --git a/drivers/avr/TWIlib.h b/drivers/avr/TWIlib.h new file mode 100644 index 0000000000..23fd1f09aa --- /dev/null +++ b/drivers/avr/TWIlib.h @@ -0,0 +1,82 @@ +/* + * 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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