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-rw-r--r--drivers/avr/TWIlib.h82
1 files changed, 82 insertions, 0 deletions
diff --git a/drivers/avr/TWIlib.h b/drivers/avr/TWIlib.h
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+++ b/drivers/avr/TWIlib.h
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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_ \ No newline at end of file