mirror of
https://github.com/RobTillaart/Arduino.git
synced 2024-09-20 00:55:58 -04:00
1c1de9bfeb
+ removed beginTransmission from read8() -> speed++ + removed endTransmission from read8() -> speed + changed address to uint8_t
120 lines
2.2 KiB
C++
120 lines
2.2 KiB
C++
//
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// FILE: PCF8574.cpp
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// AUTHOR: Rob Tillaart
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// DATE: 02-febr-2013
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// VERSION: 0.1.04
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// PURPOSE: I2C PCF8574 library for Arduino
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// URL:
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//
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// HISTORY:
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// 0.1.04 2015-05-09 removed ambiguity in read8()
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// 0.1.03 2015-03-02 address int -> uint8_t
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// 0.1.02 replaced ints with uint8_t to reduce footprint;
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// added default value for shiftLeft() and shiftRight()
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// renamed status() to lastError();
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// 0.1.01 added value(); returns last read 8 bit value (cached);
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// value() does not always reflect the latest state of the pins!
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// 0.1.00 initial version
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//
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#include "PCF8574.h"
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#include <Wire.h>
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PCF8574::PCF8574(uint8_t deviceAddress)
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{
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_address = deviceAddress;
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Wire.begin();
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// TWBR = 12; // 400KHz
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}
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// removed Wire.beginTransmission(addr);
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// with @100KHz -> 265 micros()
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// without @100KHz -> 132 micros()
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// without @400KHz -> 52 micros()
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// TODO @800KHz -> ??
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uint8_t PCF8574::read8()
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{
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if (Wire.requestFrom(_address, (uint8_t)1) != 1)
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{
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_error = 10;
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return _data; // last value
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}
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#if (ARDUINO < 100)
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_data = Wire.receive();
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#else
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_data = Wire.read();
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#endif
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return _data;
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}
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uint8_t PCF8574::value()
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{
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return _data;
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}
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void PCF8574::write8(uint8_t value)
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{
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_data = value;
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Wire.beginTransmission(_address);
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Wire.write(_data);
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_error = Wire.endTransmission();
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}
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// pin should be 0..7
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uint8_t PCF8574::read(uint8_t pin)
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{
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PCF8574::read8();
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return (_data & (1<<pin)) > 0;
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}
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// pin should be 0..7
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void PCF8574::write(uint8_t pin, uint8_t value)
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{
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PCF8574::read8();
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if (value == LOW)
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{
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_data &= ~(1<<pin);
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}
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else
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{
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_data |= (1<<pin);
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}
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PCF8574::write8(_data);
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}
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// pin should be 0..7
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void PCF8574::toggle(uint8_t pin)
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{
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PCF8574::read8();
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_data ^= (1 << pin);
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PCF8574::write8(_data);
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}
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// n should be 0..7
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void PCF8574::shiftRight(uint8_t n)
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{
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if (n == 0 || n > 7 ) return;
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PCF8574::read8();
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_data >>= n;
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PCF8574::write8(_data);
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}
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// n should be 0..7
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void PCF8574::shiftLeft(uint8_t n)
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{
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if (n == 0 || n > 7) return;
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PCF8574::read8();
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_data <<= n;
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PCF8574::write8(_data);
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}
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int PCF8574::lastError()
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{
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int e = _error;
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_error = 0;
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return e;
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}
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//
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// END OF FILE
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//
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