PCF8575 16-bit port device support added

IODevice.h

@@ -1,4 +1,5 @@
 /*
+ *  © 2023, Paul Antoine, Discord user @ADUBOURG
  *  © 2021, Neil McKechnie. All rights reserved.
  *  
  *  This file is part of DCC++EX API
@@ -410,6 +411,7 @@ private:
 #include "IO_MCP23008.h"
 #include "IO_MCP23017.h"
 #include "IO_PCF8574.h"
+#include "IO_PCF8575.h"
 #include "IO_duinoNodes.h"
 #include "IO_EXIOExpander.h"
 

IO_PCF8575.h

@@ -0,0 +1,106 @@
+/*
+ *  © 2023, Paul Antoine, and Discord user @ADUBOURG
+ *  © 2021, Neil McKechnie. All rights reserved.
+ *  
+ *  This file is part of DCC++EX API
+ *
+ *  This is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  It is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with CommandStation.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/* 
+ * The PCF8575 is a simple device; it only has one register.  The device 
+ * input/output mode and pullup are configured through this, and the 
+ * output state is written and the input state read through it too.
+ * 
+ * This is accomplished by having a weak resistor in series with the output,
+ * and a read-back of the other end of the resistor.  As an output, the 
+ * pin state is set to 1 or 0, and the output voltage goes to +5V or 0V
+ * (through the weak resistor).
+ * 
+ * In order to use the pin as an input, the output is written as
+ * a '1' in order to pull up the resistor.  Therefore the input will be
+ * 1 unless the pin is pulled down externally, in which case it will be 0.
+ * 
+ * As a consequence of this approach, it is not possible to use the device for
+ * inputs without pullups.
+ */
+
+#ifndef IO_PCF8575_H
+#define IO_PCF8575_H
+
+#include "IO_GPIOBase.h"
+#include "FSH.h"
+
+class PCF8575 : public GPIOBase<uint16_t> {
+public:
+  static void create(VPIN firstVpin, uint8_t nPins, uint8_t I2CAddress, int interruptPin=-1) {
+    if (checkNoOverlap(firstVpin, nPins, I2CAddress)) new PCF8575(firstVpin, min(nPins,(uint8_t)16), I2CAddress, interruptPin);
+  }
+
+private:
+  PCF8575(VPIN firstVpin, uint8_t nPins, uint8_t I2CAddress, int interruptPin=-1)
+    : GPIOBase<uint16_t>((FSH *)F("PCF8575"), firstVpin, nPins, I2CAddress, interruptPin)
+  {
+    requestBlock.setReadParams(_I2CAddress, inputBuffer, sizeof(inputBuffer));
+  }
+  
+  // The pin state is '1' if the pin is an input or if it is an output set to 1.  Zero otherwise. 
+  void _writeGpioPort() override {
+    I2CManager.write(_I2CAddress, 2, _portOutputState | ~_portMode, (_portOutputState | ~_portMode)>>8);
+  }
+
+  // The PCF8575 handles inputs by applying a weak pull-up when output is driven to '1'.
+  // Therefore, writing '1' in _writePortModes is enough to set the module to input mode 
+  // and enable pull-up.
+  void _writePullups() override { }
+
+  // The pin state is '1' if the pin is an input or if it is an output set to 1.  Zero otherwise. 
+  void _writePortModes() override {
+    I2CManager.write(_I2CAddress, 2, _portOutputState | ~_portMode, (_portOutputState | ~_portMode)>>8);
+  }
+
+  // In immediate mode, _readGpioPort reads the device GPIO port and updates _portInputState accordingly.
+  //  When not in immediate mode, it initiates a request using the request block and returns.
+  //  When the request completes, _processCompletion finishes the operation.
+  void _readGpioPort(bool immediate) override {
+    if (immediate) {
+      uint8_t buffer[2];
+      I2CManager.read(_I2CAddress, buffer, 2);
+      _portInputState = ((uint16_t)buffer[1]<<8) | buffer[0];
+    } else {
+      requestBlock.wait(); // Wait for preceding operation to complete
+      // Issue new request to read GPIO register
+      I2CManager.queueRequest(&requestBlock);
+    }
+  }
+
+  // This function is invoked when an I/O operation on the requestBlock completes.
+  void _processCompletion(uint8_t status) override {
+    if (status == I2C_STATUS_OK) 
+      _portInputState = ((uint16_t)inputBuffer[1]<<8) | inputBuffer[0];
+    else  
+      _portInputState = 0xffff;
+  }
+
+  // Set up device ports
+  void _setupDevice() override { 
+    _writePortModes();
+    _writeGpioPort();
+    _writePullups();
+  }
+ 
+  uint8_t inputBuffer[2];
+};
+
+#endif

myHal.cpp_example.txt

@@ -88,6 +88,21 @@ void halSetup() {
   //PCF8574::create(200, 8, 0x23, 40);
 
 
+  //=======================================================================
+  // The following directive defines a PCF8575 16-port I2C GPIO Extender module.
+  //=======================================================================
+  // The parameters are: 
+  //   First Vpin=200
+  //   Number of VPINs=16 (numbered 200-215)
+  //   I2C address of module=0x23
+
+  //PCF8575::create(200, 16, 0x23);
+
+
+  // Alternative form using INT pin (see above)
+
+  //PCF8575::create(200, 16, 0x23, 40);
+
   //=======================================================================
   // The following directive defines an HCSR04 ultrasonic ranging module.
   //=======================================================================