From 858f960d1e95cc9327d0b4a4fd02f0038510aa1f Mon Sep 17 00:00:00 2001
From: Renzo Mischianti <renzo.mischianti@gmail.com>
Date: Tue, 26 May 2020 22:06:42 +0200
Subject: [PATCH] Manage initialization of pin INPUT with HIGH value to set pin
 mode input, so pull-up and pull-down resistor for correct management is
 needed now, to restore previous decomment #define PCF8574_SOFT_INITIALIZATION

---
 PCF8574.cpp | 27 +++++++++++++++++++++++----
 PCF8574.h   |  3 +++
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/PCF8574.cpp b/PCF8574.cpp
index 772df81..f34b73e 100644
--- a/PCF8574.cpp
+++ b/PCF8574.cpp
@@ -200,12 +200,18 @@ void PCF8574::begin(){
 
 
 		DEBUG_PRINT("resetInitial pin ");
+#ifdef PCF8574_SOFT_INITIALIZATION
 		resetInitial = writeModeUp | readModePullUp;
+#else
+		resetInitial = writeModeUp | readMode;
+#endif
 		DEBUG_PRINTLN( resetInitial, BIN);
 
+		_wire->beginTransmission(_address);
 		_wire->write(resetInitial);
 
-		byteBuffered = resetInitial;
+		initialBuffer = writeModeUp | readModePullUp;
+		byteBuffered = initialBuffer;
 		writeByteBuffered = writeModeUp;
 
 		DEBUG_PRINTLN("Start end trasmission if stop here check pullup resistor.");
@@ -501,7 +507,11 @@ void PCF8574::readBuffer(bool force){
 		if ((bit(7) & writeMode)>0) digitalInput.p7 = ((writeByteBuffered & bit(7))>0)?HIGH:LOW;
 
 		//if ((byteBuffered & readModePullDown)>0 and (~byteBuffered & readModePullUp)>0){
-			byteBuffered = (resetInitial & readMode) | (byteBuffered  & ~readMode); //~readMode & byteBuffered;
+
+//		byteBuffered = (resetInitial & readMode) | (byteBuffered  & ~readMode); //~readMode & byteBuffered;
+
+		byteBuffered = (initialBuffer & readMode) | (byteBuffered  & ~readMode); //~readMode & byteBuffered;
+
 			DEBUG_PRINT("Buffer hight value readed set readed ");
 			DEBUG_PRINTLN(byteBuffered, BIN);
 		//}
@@ -536,7 +546,8 @@ void PCF8574::readBuffer(bool force){
 		byte byteRead = byteBuffered | writeByteBuffered;
 
 		//if ((byteBuffered & readModePullDown)>0 and (~byteBuffered & readModePullUp)>0){
-			byteBuffered = (resetInitial & readMode) | (byteBuffered  & ~readMode); //~readMode & byteBuffered;
+//			byteBuffered = (resetInitial & readMode) | (byteBuffered  & ~readMode); //~readMode & byteBuffered;
+		byteBuffered = (initialBuffer & readMode) | (byteBuffered  & ~readMode); //~readMode & byteBuffered;
 			DEBUG_PRINT("Buffer hight value readed set readed ");
 			DEBUG_PRINTLN(byteBuffered, BIN);
 		//}
@@ -565,7 +576,7 @@ uint8_t PCF8574::digitalRead(uint8_t pin, bool forceReadNow){
 //	DEBUG_PRINTLN(byteBuffered, BIN);
 
 
-	if (((bit(pin) & (readModePullDown & byteBuffered))>0) or (bit(pin) & (readModePullUp & ~byteBuffered))>0 ){
+	if ((((bit(pin) & (readModePullDown & byteBuffered))>0) or (bit(pin) & (readModePullUp & ~byteBuffered))>0 )){
 		DEBUG_PRINTLN(" ...Pin already set");
 		  if ((bit(pin) & byteBuffered)>0){
 			  value = HIGH;
@@ -645,10 +656,18 @@ void PCF8574::digitalWrite(uint8_t pin, uint8_t value){
 
 	// writeByteBuffered = writeByteBuffered & (~writeMode & byteBuffered);
 	byteBuffered = (writeByteBuffered & writeMode) | (resetInitial & readMode);
+
+	// byteBuffered = (writeByteBuffered & writeMode) | (byteBuffered & readMode);
 	DEBUG_PRINT(" byteBuffered ");
 	DEBUG_PRINTLN(byteBuffered, BIN);
 
+	DEBUG_PRINT("Going to write data ");
+	DEBUG_PRINTLN(writeByteBuffered, BIN);
+
 	_wire->write(byteBuffered);
+
+	byteBuffered = (writeByteBuffered & writeMode) | (initialBuffer & readMode);
+
 //	byteBuffered = (writeByteBuffered & writeMode) & (byteBuffered & readMode);
 	DEBUG_PRINTLN("Start end trasmission if stop here check pullup resistor.");
 
diff --git a/PCF8574.h b/PCF8574.h
index 177e2f1..a8d52e1 100644
--- a/PCF8574.h
+++ b/PCF8574.h
@@ -55,6 +55,8 @@
 // Uncomment for low memory usage this prevent use of complex DigitalInput structure and free 7byte of memory
 // #define PCF8574_LOW_LATENCY
 
+//#define PCF8574_SOFT_INITIALIZATION
+
 // Select an algorithm to manage encoder progression
 //#define BASIC_ENCODER_ALGORITHM
 #define MISCHIANTI_ENCODER_ALGORITHM
@@ -186,6 +188,7 @@ private:
 	byte readModePullDown 	= 	B00000000;
 	byte byteBuffered 		= 	B00000000;
 	byte resetInitial		= 	B00000000;
+	byte initialBuffer		= 	B00000000;
 	unsigned long lastReadMillis = 0;
 
 	byte writeByteBuffered = B00000000;