Added new utility library to drive a PCF8574/PCF8574A for the SAB

src/libs/PCF8574/PCF8574.cpp

@@ -0,0 +1,50 @@
+#include "PCF8574.h"
+
+PCF8574::PCF8574(uint8_t address, TwoWire &twc) : _twc(twc),_address(address),_pinConfig(0b11111111)
+{
+  
+}
+
+void PCF8574::begin()
+{
+  _twc.begin();
+  _twc.beginTransmission(_address);
+  _twc.write(_pinConfig);
+  _twc.endTransmission();
+}
+
+void PCF8574::pinMode(Pin pin, boolean mode)
+{
+  uint8_t mask = mode ? ~pin : pin; //0 INPUT - 1 OUTPUT
+
+  if(mode)
+    _pinConfig = _pinConfig & mask;
+  else
+    _pinConfig = _pinConfig | mask;
+  
+  _pinConfig = _pinConfig | mask;
+  _twc.beginTransmission(_address);
+  _twc.write(_pinConfig);
+  _twc.endTransmission();
+}
+
+void PCF8574::digitalWrite(Pin pin, boolean mode)
+{
+  uint8_t mask = mode ? pin : ~pin; //0 LOW, 1 HIGH
+  if(mode)
+    _pinConfig = _pinConfig | mask;
+  else
+    _pinConfig = _pinConfig & mask;
+
+  _twc.beginTransmission(_address);
+  _twc.write(_pinConfig);
+  _twc.endTransmission();
+}
+
+boolean PCF8574::digitalRead(Pin pin)
+{
+  uint8_t reg = 0b00000000;
+  _twc.requestFrom((uint8_t)_address,(uint8_t)1,(uint8_t)true);
+  while(_twc.available())reg = _twc.read();
+  return (reg & pin) == 0 ? 0 : 1;
+}

src/libs/PCF8574/PCF8574.h

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+#ifndef PCF8574_H
+#define PCF8574_H
+#include <Arduino.h>
+#include <Wire.h>
+
+/***
+* A very simple class to drive a PCF8574 chip
+* 
+* Anatole SCHRAMM-HENRY -- Th3maz1ng
+***/
+
+class PCF8574
+{
+  public:
+    enum Pin{P0 = 1, P1 = 2, P2 = 4, P3 = 8, P4 = 16, P5 = 32, P6 = 64, P7 = 128};
+    
+    PCF8574(uint8_t address, TwoWire &twc = Wire);
+    void begin();
+    void pinMode(Pin pin, boolean mode = INPUT);
+    void digitalWrite(Pin pin, boolean mode);
+    boolean digitalRead(Pin pin);
+  private:
+    TwoWire &_twc;
+    uint8_t _address;
+    uint8_t _pinConfig;
+  protected: 
+};
+
+#endif

src/libs/PCF8574/PCF8574.ino

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+#include "PCF8574.h"
+
+//Example programm with blink on P0 and digitalRead on P1 - P7
+
+PCF8574 pcf(0x27);
+
+void setup() {
+  Serial.begin(9600);
+  // put your setup code here, to run once:
+  pcf.begin();
+  pcf.pinMode(PCF8574::P0,OUTPUT);
+}
+
+void loop() {
+  // put your main code here, to run repeatedly:
+  Serial.print(pcf.digitalRead(PCF8574::P0));Serial.print(pcf.digitalRead(PCF8574::P1));Serial.print(pcf.digitalRead(PCF8574::P2));Serial.print(pcf.digitalRead(PCF8574::P3));Serial.print(pcf.digitalRead(PCF8574::P4));Serial.print(pcf.digitalRead(PCF8574::P5));Serial.print(pcf.digitalRead(PCF8574::P6));Serial.println(pcf.digitalRead(PCF8574::P7));
+  //pcf.digitalRead(PCF8574::P0);
+  pcf.pinMode(PCF8574::P0, HIGH);
+  delay(200);
+  pcf.pinMode(PCF8574::P0, LOW);
+  delay(200);
+}