mirror of https://github.com/ArduPilot/ardupilot
75 lines
1.3 KiB
C
75 lines
1.3 KiB
C
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/*
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Copyright (C) Dean Camera, 2010.
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dean [at] fourwalledcubicle [dot] com
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www.fourwalledcubicle.com
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*/
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#include "TWI.h"
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bool 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 false;
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}
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}
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_delay_us(10);
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}
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if (!(BusCaptured))
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{
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TWCR = (1 << TWEN);
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return false;
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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 false;
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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 true;
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default:
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TWCR = ((1 << TWINT) | (1 << TWSTO) | (1 << TWEN));
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return false;
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}
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}
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}
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