/* * TWIlib.c * * Created: 6/01/2014 10:41:33 PM * Author: Chris Herring */ #include <avr/io.h> #include <avr/interrupt.h> #include "TWIlib.h" #include <util/delay.h> #include "print.h" // Global transmit buffer volatile uint8_t *TWITransmitBuffer; // 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) TWIInfoStruct TWIInfo; void TWIInit() { TWIInfo.mode = Ready; TWIInfo.errorCode = 0xFF; TWIInfo.repStart = 0; // Set pre-scalers (no pre-scaling) TWSR = 0; // Set bit rate TWBR = ((F_CPU / TWI_FREQ) - 16) / 2; // Enable TWI and interrupt TWCR = (1 << TWIE) | (1 << TWEN); } uint8_t isTWIReady() { if ( (TWIInfo.mode == Ready) | (TWIInfo.mode == RepeatedStartSent) ) { return 1; } else { if(TWIInfo.mode == Initializing){ switch(TWIInfo.errorCode){ case TWI_SUCCESS: case TWI_NO_RELEVANT_INFO: break; case TWI_LOST_ARBIT: case TWI_MT_DATA_NACK: // Some kind of I2C error, reset and re-init xprintf("I2C init error: %d\n", TWIInfo.errorCode); TWCR = (1 << TWINT)|(1 << TWSTO); TWIInit(); break; default: xprintf("Other i2c init error: %d\n", TWIInfo.errorCode); } } return 0; } } void TWITransmitData(void *const TXdata, uint8_t dataLen, uint8_t repStart, uint8_t blocking) { // Wait until ready while (!isTWIReady()) {_delay_us(1);} // Reset the I2C stuff TWCR = (1 << TWINT)|(1 << TWSTO); TWIInit(); // Set repeated start mode TWIInfo.repStart = repStart; // Copy transmit info to global variables TWITransmitBuffer = (uint8_t *)TXdata; TXBuffLen = dataLen; TXBuffIndex = 0; // If a repeated start has been sent, then devices are already listening for an address // and another start does not need to be sent. if (TWIInfo.mode == RepeatedStartSent) { TWIInfo.mode = Initializing; TWDR = TWITransmitBuffer[TXBuffIndex++]; // Load data to transmit buffer TWISendTransmit(); // Send the data } else // Otherwise, just send the normal start signal to begin transmission. { TWIInfo.mode = Initializing; TWISendStart(); } if(blocking){ // Wait until ready while (!isTWIReady()){_delay_us(1);} } } // uint8_t TWITransmitData(void *const TXdata, uint8_t dataLen, uint8_t repStart) // { // if (dataLen <= TXMAXBUFLEN) // { // // Wait until ready // while (!isTWIReady()) {_delay_us(1);} // // Set repeated start mode // TWIInfo.repStart = repStart; // // Copy data into the transmit buffer // uint8_t *data = (uint8_t *)TXdata; // for (int i = 0; i < dataLen; i++) // { // TWITransmitBuffer[i] = data[i]; // } // // Copy transmit info to global variables // TXBuffLen = dataLen; // TXBuffIndex = 0; // // If a repeated start has been sent, then devices are already listening for an address // // and another start does not need to be sent. // if (TWIInfo.mode == RepeatedStartSent) // { // TWIInfo.mode = Initializing; // TWDR = TWITransmitBuffer[TXBuffIndex++]; // Load data to transmit buffer // TWISendTransmit(); // Send the data // } // else // Otherwise, just send the normal start signal to begin transmission. // { // TWIInfo.mode = Initializing; // TWISendStart(); // } // } // else // { // return 1; // return an error if data length is longer than buffer // } // return 0; // } uint8_t TWIReadData(uint8_t TWIaddr, uint8_t bytesToRead, uint8_t repStart) { // Check if number of bytes to read can fit in the RXbuffer if (bytesToRead < RXMAXBUFLEN) { // Reset buffer index and set RXBuffLen to the number of bytes to read RXBuffIndex = 0; RXBuffLen = bytesToRead; // Create the one value array for the address to be transmitted uint8_t TXdata[1]; // Shift the address and AND a 1 into the read write bit (set to write mode) TXdata[0] = (TWIaddr << 1) | 0x01; // Use the TWITransmitData function to initialize the transfer and address the slave TWITransmitData(TXdata, 1, repStart, 0); } else { return 0; } return 1; } ISR (TWI_vect) { switch (TWI_STATUS) { // ----\/ ---- MASTER TRANSMITTER OR WRITING ADDRESS ----\/ ---- // case TWI_MT_SLAW_ACK: // SLA+W transmitted and ACK received // Set mode to Master Transmitter TWIInfo.mode = MasterTransmitter; case TWI_START_SENT: // Start condition has been transmitted case TWI_MT_DATA_ACK: // Data byte has been transmitted, ACK received if (TXBuffIndex < TXBuffLen) // If there is more data to send { TWDR = TWITransmitBuffer[TXBuffIndex++]; // Load data to transmit buffer TWIInfo.errorCode = TWI_NO_RELEVANT_INFO; TWISendTransmit(); // Send the data } // This transmission is complete however do not release bus yet else if (TWIInfo.repStart) { TWIInfo.errorCode = 0xFF; TWISendStart(); } // All transmissions are complete, exit else { TWIInfo.mode = Ready; TWIInfo.errorCode = 0xFF; TWISendStop(); } break; // ----\/ ---- MASTER RECEIVER ----\/ ---- // case TWI_MR_SLAR_ACK: // SLA+R has been transmitted, ACK has been received // Switch to Master Receiver mode TWIInfo.mode = MasterReceiver; // If there is more than one byte to be read, receive data byte and return an ACK if (RXBuffIndex < RXBuffLen-1) { TWIInfo.errorCode = TWI_NO_RELEVANT_INFO; TWISendACK(); } // Otherwise when a data byte (the only data byte) is received, return NACK else { TWIInfo.errorCode = TWI_NO_RELEVANT_INFO; TWISendNACK(); } break; case TWI_MR_DATA_ACK: // Data has been received, ACK has been transmitted. /// -- HANDLE DATA BYTE --- /// TWIReceiveBuffer[RXBuffIndex++] = TWDR; // If there is more than one byte to be read, receive data byte and return an ACK if (RXBuffIndex < RXBuffLen-1) { TWIInfo.errorCode = TWI_NO_RELEVANT_INFO; TWISendACK(); } // Otherwise when a data byte (the only data byte) is received, return NACK else { TWIInfo.errorCode = TWI_NO_RELEVANT_INFO; TWISendNACK(); } break; case TWI_MR_DATA_NACK: // Data byte has been received, NACK has been transmitted. End of transmission. /// -- HANDLE DATA BYTE --- /// TWIReceiveBuffer[RXBuffIndex++] = TWDR; // This transmission is complete however do not release bus yet if (TWIInfo.repStart) { TWIInfo.errorCode = 0xFF; TWISendStart(); } // All transmissions are complete, exit else { TWIInfo.mode = Ready; TWIInfo.errorCode = 0xFF; TWISendStop(); } break; // ----\/ ---- MT and MR common ----\/ ---- // case TWI_MR_SLAR_NACK: // SLA+R transmitted, NACK received case TWI_MT_SLAW_NACK: // SLA+W transmitted, NACK received case TWI_MT_DATA_NACK: // Data byte has been transmitted, NACK received case TWI_LOST_ARBIT: // Arbitration has been lost // Return error and send stop and set mode to ready if (TWIInfo.repStart) { TWIInfo.errorCode = TWI_STATUS; TWISendStart(); } // All transmissions are complete, exit else { TWIInfo.mode = Ready; TWIInfo.errorCode = TWI_STATUS; TWISendStop(); } break; case TWI_REP_START_SENT: // Repeated start has been transmitted // Set the mode but DO NOT clear TWINT as the next data is not yet ready TWIInfo.mode = RepeatedStartSent; break; // ----\/ ---- SLAVE RECEIVER ----\/ ---- // // TODO IMPLEMENT SLAVE RECEIVER FUNCTIONALITY // ----\/ ---- SLAVE TRANSMITTER ----\/ ---- // // TODO IMPLEMENT SLAVE TRANSMITTER FUNCTIONALITY // ----\/ ---- MISCELLANEOUS STATES ----\/ ---- // case TWI_NO_RELEVANT_INFO: // It is not really possible to get into this ISR on this condition // Rather, it is there to be manually set between operations break; case TWI_ILLEGAL_START_STOP: // Illegal START/STOP, abort and return error TWIInfo.errorCode = TWI_ILLEGAL_START_STOP; TWIInfo.mode = Ready; TWISendStop(); break; } }