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arduino-cli/libraries/Rtc_by_Makuna/src/ThreeWire.h

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+#pragma once
+
+//ThreeWire command Read/Write flag 
+const uint8_t THREEWIRE_READFLAG = 0x01;
+
+class ThreeWire 
+{
+public:
+    ThreeWire(uint8_t ioPin, uint8_t clkPin, uint8_t cePin) :
+        _ioPin(ioPin),
+        _clkPin(clkPin),
+        _cePin(cePin)
+    {
+    }
+
+    void begin() {
+        resetPins();
+    }
+
+    void end() {
+        resetPins();
+    }
+
+    void beginTransmission(uint8_t command) {
+        digitalWrite(_cePin, LOW); // default, not enabled
+        pinMode(_cePin, OUTPUT);
+
+        digitalWrite(_clkPin, LOW); // default, clock low
+        pinMode(_clkPin, OUTPUT);
+
+        pinMode(_ioPin, OUTPUT);
+
+        digitalWrite(_cePin, HIGH); // start the session
+        delayMicroseconds(4);           // tCC = 4us
+
+        write(command, (command & THREEWIRE_READFLAG) == THREEWIRE_READFLAG);
+    }
+
+    void endTransmission() {
+        digitalWrite(_cePin, LOW);
+        delayMicroseconds(4);           // tCWH = 4us
+    }
+
+    void write(uint8_t value, bool isDataRequestCommand = false) {
+        for (uint8_t bit = 0; bit < 8; bit++) {
+            digitalWrite(_ioPin, value & 0x01);
+            delayMicroseconds(1);     // tDC = 200ns
+
+            // clock up, data is read by DS1302
+            digitalWrite(_clkPin, HIGH);
+            delayMicroseconds(1);     // tCH = 1000ns, tCDH = 800ns
+
+            // for the last bit before a read
+            // Set IO line for input before the clock down
+            if (bit == 7 && isDataRequestCommand) {
+                pinMode(_ioPin, INPUT);
+            }
+
+            digitalWrite(_clkPin, LOW);
+            delayMicroseconds(1);     // tCL=1000ns, tCDD=800ns
+
+            value >>= 1;
+        }
+    }
+
+    uint8_t read() {
+        uint8_t value = 0;
+
+        for (uint8_t bit = 0; bit < 8; bit++) {
+            // first bit is present on io pin, so only clock the other
+            // bits
+            value |= (digitalRead(_ioPin) << bit);
+        
+            // Clock up, prepare for next
+            digitalWrite(_clkPin, HIGH);
+            delayMicroseconds(1);
+
+            // Clock down, value is ready after some time.
+            digitalWrite(_clkPin, LOW);
+            delayMicroseconds(1);        // tCL=1000ns, tCDD=800ns
+        }
+
+        return value;
+    }
+
+private:
+    const uint8_t _ioPin;
+    const uint8_t _clkPin;
+    const uint8_t _cePin;
+
+    void resetPins() {
+        // just making sure they are in a default low power use state
+        // as required state is set when transmissions are started
+        // three wire devices have internal pull downs so they will be low
+        pinMode(_clkPin, INPUT);
+        pinMode(_ioPin, INPUT);
+        pinMode(_cePin, INPUT);
+    }
+};