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144 lines
3.0 KiB
144 lines
3.0 KiB
/*
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Copyright (C) Dean Camera, 2011.
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dean [at] fourwalledcubicle [dot] com
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www.lufa-lib.org
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*/
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#include "TWI.h"
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uint8_t TWI_StartTransmission(const uint8_t SlaveAddress,
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const uint8_t TimeoutMS)
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{
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for (;;)
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{
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bool BusCaptured = false;
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uint16_t TimeoutRemaining;
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TWCR = ((1 << TWINT) | (1 << TWSTA) | (1 << TWEN));
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TimeoutRemaining = (TimeoutMS * 100);
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while (TimeoutRemaining-- && !(BusCaptured))
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{
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if (TWCR & (1 << TWINT))
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{
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switch (TWSR & TW_STATUS_MASK)
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{
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case TW_START:
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case TW_REP_START:
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BusCaptured = true;
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break;
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case TW_MT_ARB_LOST:
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TWCR = ((1 << TWINT) | (1 << TWSTA) | (1 << TWEN));
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continue;
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default:
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TWCR = (1 << TWEN);
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return TWI_ERROR_BusFault;
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}
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}
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_delay_us(10);
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}
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if (!(TimeoutRemaining))
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{
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TWCR = (1 << TWEN);
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return TWI_ERROR_BusCaptureTimeout;
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}
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TWDR = SlaveAddress;
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TWCR = ((1 << TWINT) | (1 << TWEN));
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TimeoutRemaining = (TimeoutMS * 100);
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while (TimeoutRemaining--)
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{
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if (TWCR & (1 << TWINT))
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break;
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_delay_us(10);
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}
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if (!(TimeoutRemaining))
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return TWI_ERROR_SlaveResponseTimeout;
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switch (TWSR & TW_STATUS_MASK)
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{
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case TW_MT_SLA_ACK:
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case TW_MR_SLA_ACK:
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return TWI_ERROR_NoError;
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default:
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TWCR = ((1 << TWINT) | (1 << TWSTO) | (1 << TWEN));
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return TWI_ERROR_SlaveNotReady;
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}
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}
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}
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uint8_t TWI_ReadPacket(const uint8_t SlaveAddress,
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const uint8_t TimeoutMS,
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const uint8_t* InternalAddress,
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uint8_t InternalAddressLen,
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uint8_t* Buffer,
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uint8_t Length)
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{
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uint8_t ErrorCode;
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if ((ErrorCode = TWI_WritePacket(SlaveAddress, TimeoutMS, InternalAddress, InternalAddressLen,
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NULL, 0)) != TWI_ERROR_NoError)
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{
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return ErrorCode;
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}
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if ((ErrorCode = TWI_StartTransmission((SlaveAddress & TWI_DEVICE_ADDRESS_MASK) | TWI_ADDRESS_READ,
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TimeoutMS)) == TWI_ERROR_NoError)
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{
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while (Length--)
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{
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if (!(TWI_ReceiveByte(Buffer++, (Length == 0))))
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{
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ErrorCode = TWI_ERROR_SlaveNAK;
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break;
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}
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}
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TWI_StopTransmission();
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}
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return ErrorCode;
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}
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uint8_t TWI_WritePacket(const uint8_t SlaveAddress,
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const uint8_t TimeoutMS,
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const uint8_t* InternalAddress,
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uint8_t InternalAddressLen,
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const uint8_t* Buffer,
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uint8_t Length)
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{
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uint8_t ErrorCode;
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if ((ErrorCode = TWI_StartTransmission((SlaveAddress & TWI_DEVICE_ADDRESS_MASK) | TWI_ADDRESS_WRITE,
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TimeoutMS)) == TWI_ERROR_NoError)
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{
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while (InternalAddressLen--)
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{
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if (!(TWI_SendByte(*(InternalAddress++))))
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{
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ErrorCode = TWI_ERROR_SlaveNAK;
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break;
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}
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}
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while (Length--)
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{
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if (!(TWI_SendByte(*(Buffer++))))
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{
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ErrorCode = TWI_ERROR_SlaveNAK;
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break;
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}
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}
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TWI_StopTransmission();
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}
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return ErrorCode;
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}
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