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102 lines
2.8 KiB
102 lines
2.8 KiB
11 years ago
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/*
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TinyWireS.cpp - a wrapper class for Don Blake's usiTwiSlave routines.
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Provides TWI/I2C Slave functionality on ATtiny processers in Arduino environment.
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1/23/2011 BroHogan - brohoganx10 at gmail dot com
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**** See TinyWireS.h for Credits and Usage information ****
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This library is free software; you can redistribute it and/or modify it under the
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terms of the GNU General Public License as published by the Free Software
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Foundation; either version 2.1 of the License, or any later version.
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This program is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
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PARTICULAR PURPOSE. See the GNU General Public License for more details.
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*/
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extern "C" {
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#include <inttypes.h>
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#include "usiTwiSlave.h"
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#include <avr/interrupt.h>
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}
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#include "TinyWireS.h"
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#include "Arduino.h"
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// Constructors ////////////////////////////////////////////////////////////////
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USI_TWI_S::USI_TWI_S(){
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}
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// Public Methods //////////////////////////////////////////////////////////////
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void USI_TWI_S::begin(uint8_t slaveAddr){ // initialize I2C lib
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usiTwiSlaveInit(slaveAddr);
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}
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void USI_TWI_S::send(uint8_t data){ // send it back to master
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usiTwiTransmitByte(data);
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}
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uint8_t USI_TWI_S::available(){ // the bytes available that haven't been read yet
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return usiTwiAmountDataInReceiveBuffer();
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//return usiTwiDataInReceiveBuffer(); // This is wrong as far as the Wire API is concerned since it returns boolean and not amount
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}
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uint8_t USI_TWI_S::receive(){ // returns the bytes received one at a time
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return usiTwiReceiveByte();
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}
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// sets function called on slave write
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void USI_TWI_S::onReceive( void (*function)(uint8_t) )
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{
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usi_onReceiverPtr = function;
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}
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// sets function called on slave read
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void USI_TWI_S::onRequest( void (*function)(void) )
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{
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usi_onRequestPtr = function;
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}
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void TinyWireS_stop_check()
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{
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if (!usi_onReceiverPtr)
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{
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// no onReceive callback, nothing to do...
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return;
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}
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if (!(USISR & ( 1 << USIPF )))
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{
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// Stop not detected
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return;
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}
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uint8_t amount = usiTwiAmountDataInReceiveBuffer();
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if (amount == 0)
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{
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// no data in buffer
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return;
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}
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usi_onReceiverPtr(amount);
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}
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// Implement a delay loop that checks for the stop bit (basically direct copy of the stock arduino implementation from wiring.c)
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void tws_delay(unsigned long ms)
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{
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uint16_t start = (uint16_t)micros();
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while (ms > 0)
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{
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TinyWireS_stop_check();
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if (((uint16_t)micros() - start) >= 1000)
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{
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ms--;
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start += 1000;
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}
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}
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}
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// Preinstantiate Objects //////////////////////////////////////////////////////
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USI_TWI_S TinyWireS = USI_TWI_S();
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