From 4f3b7068ca45fc751b9f4eea34637d8e646520cc Mon Sep 17 00:00:00 2001
From: Ash-4 <81280775+Ash-4@users.noreply.github.com>
Date: Tue, 13 May 2025 12:24:16 -0500
Subject: [PATCH] PCF8574 output pin initialization parameter

---
 IO_PCF8574.h          | 13 ++++++++++---
 myHal.cpp_example.txt |  7 +++++++
 version.h             |  3 ++-
 3 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/IO_PCF8574.h b/IO_PCF8574.h
index 17241ee..c7b740c 100644
--- a/IO_PCF8574.h
+++ b/IO_PCF8574.h
@@ -1,4 +1,5 @@
 /*
+ *  © 2025 Herb Morton
  *  © 2022 Paul M Antoine
  *  © 2021, Neil McKechnie. All rights reserved.
  *  
@@ -43,15 +44,21 @@
 
 class PCF8574 : public GPIOBase<uint8_t> {
 public:
-  static void create(VPIN firstVpin, uint8_t nPins, I2CAddress i2cAddress, int interruptPin=-1) {
-    if (checkNoOverlap(firstVpin, nPins, i2cAddress)) new PCF8574(firstVpin, nPins, i2cAddress, interruptPin);
+  static void create(VPIN firstVpin, uint8_t nPins, I2CAddress i2cAddress, int interruptPin=-1, int initPortState=-1) {
+    if (checkNoOverlap(firstVpin, nPins, i2cAddress)) new PCF8574(firstVpin, nPins, i2cAddress, interruptPin, initPortState);
   }
 
 private:
-  PCF8574(VPIN firstVpin, uint8_t nPins, I2CAddress i2cAddress, int interruptPin=-1)
+  PCF8574(VPIN firstVpin, uint8_t nPins, I2CAddress i2cAddress, int interruptPin=-1, int initPortState=-1)
     : GPIOBase<uint8_t>((FSH *)F("PCF8574"), firstVpin, nPins, i2cAddress, interruptPin) 
   {
     requestBlock.setReadParams(_I2CAddress, inputBuffer, 1);
+    if (initPortState>=0) {
+      _portMode = 255;         // set all pins to output mode
+      _portInUse = 255;        // 8 ports in use 
+      _portOutputState = initPortState;  // initialize pins low-high 0-255
+      I2CManager.write(_I2CAddress, 1, initPortState);
+    }
   }
   
   // The PCF8574 handles inputs by applying a weak pull-up when output is driven to '1'.
diff --git a/myHal.cpp_example.txt b/myHal.cpp_example.txt
index f715c63..144fe1a 100644
--- a/myHal.cpp_example.txt
+++ b/myHal.cpp_example.txt
@@ -146,7 +146,14 @@ void halSetup() {
 
   //PCF8574::create(200, 8, 0x23, 40);
 
+  // Alternative form to initialize 8 pins as output
+  //  INT pin -1, when INT is not used
 
+  //PCF8574::create(200, 8, 0x23, -1, 255);  8 pins High
+  //PCF8574::create(200, 8, 0x23, -1, 0);    8 pins Low
+  //PCF8574::create(200, 8, 0x23, -1, 0b11000010);  
+  //                       pins listed sequentially from 7 to 0
+  
   //=======================================================================
   // The following directive defines a PCF8575 16-port I2C GPIO Extender module.
   //=======================================================================
diff --git a/version.h b/version.h
index 829e536..ebb4db5 100644
--- a/version.h
+++ b/version.h
@@ -3,7 +3,8 @@
 
 #include "StringFormatter.h"
 
-#define VERSION "5.5.26"
+#define VERSION "5.5.27"
+// 5.5.27 - PCF8574 output pin initialization parameter
 // 5.5.26 - PCA9554 and TCA9554/9534 I2C 8-bit GPIO expander drivers
 // 5.2.25 - IO_Bitmap and assicated Exrail macros
 // 5.5.24 - SensorCAM in I2C scan and automatically setClock