fix #47 (mcp23S17), enable interrupts (#39)

- fix #47 (MCP23S17), interrupt handling. Kudos to GlibSkunk!
- update readme.md
- minor edits.
- add address table to readme.md`

Author: RobTillaart

CHANGELOG.md

@@ -6,8 +6,16 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
 
+## [0.8.0] - 2024-11-19
+- fix #47 (MCP23S17), interrupt handling. Kudos to GlibSkunk!
+- update readme.md
+- minor edits.
+- add address table to readme.md`
+
+----
+
 ## [0.7.1] 2024-06-06
-- Fix #36, documentation bug.
+- fix #36, documentation bug.
 
 ## [0.7.0] 2024-06-06
 - fix #33 bug, kudos to JelleWilbrink
@@ -22,16 +30,16 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - update keywords.txt
 
 ## [0.6.2] 2024-03-02
-- Fix #29, add parameter to **begin(bool pullup)**
+- fix #29, add parameter to **begin(bool pullup)**
 - remove DATE field from examples as it adds no value.
 - update GitHub/actions to version v4 in workflows.
 
 ## [0.6.1] 2024-01-05
-- Fix URL in examples
+- fix URL in examples
 - minor edits
 
 ## [0.6.0] 2023-12-24
-- Fix #26, support for Arduino ESP32 S3 - breaking change
+- fix #26, support for Arduino ESP32 S3 - breaking change
 - update readme.md
 - update examples.
 

MCP23017.cpp

@@ -1,7 +1,7 @@
 //
 //    FILE: MCP23017.cpp
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.7.1
+// VERSION: 0.8.0
 // PURPOSE: Arduino library for I2C MCP23017 16 channel port expander
 //    DATE: 2019-10-12
 //     URL: https://github.com/RobTillaart/MCP23017_RT
@@ -95,6 +95,8 @@ bool MCP23017::pinMode1(uint8_t pin, uint8_t mode)
   //  only work with valid
   if ((mode == INPUT) || (mode == INPUT_PULLUP))
   {
+    //  REV D 
+    //  if (pin == 7) return false;
     val |= mask;
   }
   else if (mode == OUTPUT)
@@ -169,7 +171,6 @@ uint8_t MCP23017::read1(uint8_t pin)
     IOR = MCP23x17_GPIO_B;
     pin -= 8;
   }
-
   uint8_t val = readReg(IOR);
   if (_error != MCP23017_OK)
   {
@@ -512,10 +513,7 @@ bool MCP23017::getPullup16(uint16_t &mask)
 //
 //  INTERRUPTS (experimental, see MCP23S17 - #40)
 //
-//  TODO, catch writeReg errors
 //  TODO, MCP23x17_INT_MODE_ERROR?
-//  TODO, if register not changed no need to update?
-//  TODO, 8 bits optimize? more code vs speed?
 //
 //  pin = 0..15, mode = { RISING, FALLING, CHANGE }
 bool MCP23017::enableInterrupt(uint8_t pin, uint8_t mode)
@@ -526,34 +524,75 @@ bool MCP23017::enableInterrupt(uint8_t pin, uint8_t mode)
     return false;
   }
 
-  //  right mode
-  uint16_t intcon = readReg16(MCP23x17_INTCON_A);
+  uint8_t INTCONREG = MCP23x17_INTCON_A;
+  uint8_t DEFVALREG = MCP23x17_DEFVAL_A;
+  uint8_t GPINTENREG = MCP23x17_GPINTEN_A;
+  if (pin > 7)
+  {
+    INTCONREG = MCP23x17_INTCON_B;
+    DEFVALREG = MCP23x17_DEFVAL_B;
+    GPINTENREG = MCP23x17_GPINTEN_B;
+    pin -= 8;
+  }
+  uint8_t mask = 1 << pin;
+
+  uint8_t intcon = readReg(INTCONREG);
+  uint8_t pre_intcon = intcon;
+  if (_error != MCP23017_OK)
+  {
+    return false;
+  }
+
   if (mode == CHANGE)
   {
-    //  compare to previous value.
-    intcon &= ~(1 << pin);
+    //  Compare to previous value
+    intcon &= ~mask;
   }
   else
   {
-    uint16_t defval = readReg16(MCP23x17_DEFVAL_A);
+    //  Compare to DEFVALREG
+    intcon |= mask;
+
+    //  Get and Modify Pin's Value in DEFVALREG
+    uint8_t defval = readReg(DEFVALREG);
+    uint8_t pre_defval = defval;
     if (mode == RISING)
     {
-      intcon |= (1 << pin);
-      defval &= ~(1 << pin);  //  RISING == compare to 0
+      defval &= ~mask;   //  RISING == compare to 0
     }
     else if (mode == FALLING)
     {
-      intcon |= (1 << pin);
-      defval |= ~(1 << pin);  //  FALLING == compare to 1
+      defval |= mask;    //  FALLING == compare to 1
+    }
+    //  only write when changed.
+    if (pre_defval != defval)
+    {
+      writeReg(DEFVALREG, defval);
+      if (_error != MCP23017_OK)
+      {
+        return false;
+      }
+    }
+  }
+  //  only write when changed.
+  if (pre_intcon != intcon)
+  {
+    writeReg(INTCONREG, intcon);
+    if (_error != MCP23017_OK)
+    {
+      return false;
     }
-    writeReg16(MCP23x17_DEFVAL_A, defval);
   }
-  writeReg16(MCP23x17_INTCON_A, intcon);
 
   //  enable interrupt
-  uint16_t value = readReg16(MCP23x17_GPINTEN_A);
-  value |= (1 << pin);
-  return writeReg16(MCP23x17_GPINTEN_A, value);
+  uint8_t gpinten = readReg(GPINTENREG);
+  uint8_t pre_gpinten = gpinten;
+  gpinten |= mask;
+  if (pre_gpinten != gpinten)
+  {
+    return writeReg(GPINTENREG, gpinten);
+  }
+  return true;  //  Already enabled for pin
 }
 
 
@@ -564,10 +603,28 @@ bool MCP23017::disableInterrupt(uint8_t pin)
     _error = MCP23017_PIN_ERROR;
     return false;
   }
+
+  uint8_t GPINTENREG = MCP23x17_GPINTEN_A;
+  if (pin > 7)
+  {
+    GPINTENREG = MCP23x17_GPINTEN_B;
+    pin -= 8;
+  }
+  uint8_t mask = 1 << pin;
+
   //  disable interrupt
-  uint16_t value = readReg16(MCP23x17_GPINTEN_A);
-  value &= ~(1 << pin);
-  return writeReg16(MCP23x17_GPINTEN_A, value);
+  uint8_t gpinten = readReg(GPINTENREG);
+  uint8_t pre_gpinten = gpinten;
+  if (_error != MCP23017_OK)
+  {
+    return false;
+  }
+  gpinten &= ~mask;
+  if (pre_gpinten != gpinten)
+  {
+    return writeReg(GPINTENREG, gpinten);
+  }
+  return true;  //  Already disabled for pin
 }
 
 

MCP23017.h

@@ -2,20 +2,21 @@
 //
 //    FILE: MCP23017.h
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.7.1
+// VERSION: 0.8.0
 // PURPOSE: Arduino library for I2C MCP23017 16 channel port expander
 //    DATE: 2019-10-12
 //     URL: https://github.com/RobTillaart/MCP23017_RT
 //
-// WARNING: please read REV D note in readme.md.
+// WARNING: please read REV D note in readme.md 
+//          about pin 7 and 15 and INPUT mode.
 
 
 #include "Arduino.h"
 #include "Wire.h"
 #include "MCP23x17_registers.h"
 
 
-#define MCP23017_LIB_VERSION              (F("0.7.1"))
+#define MCP23017_LIB_VERSION              (F("0.8.0"))
 
 #define MCP23017_OK                       0x00
 #define MCP23017_PIN_ERROR                0x81
@@ -39,6 +40,7 @@ class MCP23017
   //       single pin interface
   //       mode = INPUT, OUTPUT, INPUT_PULLUP (= same as INPUT)
   //             do not use 0, 1 for mode.
+  //       See readme.md section REV D
   bool     pinMode1(uint8_t pin, uint8_t mode);
   bool     write1(uint8_t pin, uint8_t value);
   uint8_t  read1(uint8_t pin);
@@ -51,7 +53,7 @@ class MCP23017
 
   //       8 pins interface
   //       port  = 0..1
-  //       mask  = 0x00..0xFF  bit pattern, 
+  //       mask  = 0x00..0xFF  bit pattern,
   //               bit 0 = output mode, bit 1 = input mode
   //       value = bit pattern.
   bool     pinMode8(uint8_t port, uint8_t mask);
@@ -82,7 +84,7 @@ class MCP23017
   //       pin = 0..15, mode = { RISING, FALLING, CHANGE }
   bool     enableInterrupt(uint8_t pin, uint8_t mode);
   bool     disableInterrupt(uint8_t pin);
-  
+
   //       mask = 0x0000..0xFFFF  (overrides all earlier settings.
   bool     enableInterrupt16(uint16_t mask, uint8_t mode);
   bool     disableInterrupt16(uint16_t mask);
@@ -121,7 +123,7 @@ class MCP23017
 };
 
 
-/*  
+/*
 TODO
 - can it protect the user
 - can we detect REV D chips (over I2C)
@@ -130,7 +132,7 @@ class MCP23017_REVD : public MCP23017
 {
 public:
   MCP23017_REVD(uint8_t address, TwoWire *wire = &Wire);
-  
+
 - GPA7 and GPB7 should be set to output in constructor
 - GPA7 and GPB7 output mode may not change in any call
 - GPA7 and GPB7 should return last written value for read.