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https://github.com/RobTillaart/Arduino.git
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b4ae62b533
Because a write() used a read8() first, did the clear/set, then send it back, you had an error if you did a write() on a pin while another input was just pulled low externally added readButton() and readButton8() which set the pin(s) high, read, and then restore to last written state. Also added begin() te get it in a known state
163 lines
3.3 KiB
C++
163 lines
3.3 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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// 0.1.05 2016-04-28 Septillion
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// added dataOut so a write() doesn't read first,
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// possibly corrupting a input pin;
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// fixed shift comment, should read 1..7;
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// added begin() to be sure it's in a known state,
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// states could be different if uC is reset and the PCF8574 isn't;
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// added buttonRead() and buttonRead8()
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// which only effect the ouput while reading
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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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//added 0.1.05
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void PCF8574::begin()
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{
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PCF8574::write8(0xFF);
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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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//added 0.1.05
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uint8_t PCF8574::valueOut ()
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{
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return _dataOut;
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}
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void PCF8574::write8(uint8_t value)
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{
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_dataOut = value;
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Wire.beginTransmission(_address);
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Wire.write(_dataOut);
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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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//Don't read because we could bring pulled low inputs into output state
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//PCF8574::read8();
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if (value == LOW)
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{
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_dataOut &= ~(1<<pin);
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}
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else
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{
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_dataOut |= (1<<pin);
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}
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PCF8574::write8(_dataOut);
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}
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uint8_t PCF8574::readButton8()
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{
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uint8_t temp = _dataOut;
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PCF8574::begin();
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uint8_t rtn = PCF8574::read8();
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PCF8574::write8(temp);
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return rtn;
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}
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uint8_t PCF8574::readButton(uint8_t pin)
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{
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uint8_t temp = _dataOut;
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PCF8574::write(pin, HIGH);
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uint8_t rtn = PCF8574::read(pin);
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PCF8574::write8(temp);
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return rtn;
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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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//Same as write
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//Don't read because that may upset pulled low inputs
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//PCF8574::read8();
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_dataOut ^= (1 << pin);
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PCF8574::write8(_dataOut);
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}
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// n should be 1..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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_dataOut >>= n;
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PCF8574::write8(_dataOut);
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}
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// n should be 1..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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_dataOut <<= n;
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PCF8574::write8(_dataOut);
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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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