Merge pull request #6 from RobTillaart/develop

fix #5 + minor refactor + isConnected()

PCF8575.cpp

@@ -2,13 +2,14 @@
 //    FILE: PCF8575.cpp
 //  AUTHOR: Rob Tillaart
 //    DATE: 2020-07-20
-// VERSION: 0.0.2
+// VERSION: 0.0.3
 // PURPOSE: Arduino library for PCF8575 - 16 channel I2C IO expander
 //     URL: https://github.com/RobTillaart/PCF8575
 //
 // HISTORY:
 // 0.0.1   2020-07-20 initial version
 // 0.0.2   2020-07-21 fix reverse(); refactor;
+// 0.0.3   2020-07-29 fix #5 reverse() + refactor.
 
 #include "PCF8575.h"
 
@@ -36,6 +37,12 @@ void PCF8575::begin(uint16_t val)
   PCF8575::write16(val);
 }
 
+bool PCF8575::isConnected()
+{
+  Wire.beginTransmission(_address);
+  return Wire.endTransmission() == 0;
+}
+
 uint16_t PCF8575::read16()
 {
   if (Wire.requestFrom(_address, (uint8_t)2) != 2)
@@ -98,63 +105,62 @@ void PCF8575::toggle(const uint8_t pin)
 
 void PCF8575::toggleMask(const uint16_t mask)
 {
-  _dataOut ^= mask;
-  PCF8575::write16(_dataOut);
+  PCF8575::write16(_dataOut ^ mask);
 }
 
 void PCF8575::shiftRight(const uint8_t n)
 {
   if ((n == 0) || (_dataOut == 0)) return;
-  if (n > 15) _dataOut = 0;          // shift 8++ clears all, valid...
-  if (_dataOut != 0) _dataOut >>= n; // only shift if there are bits set
+  if (n > 15) _dataOut = 0;       // shift 8++ clears all, valid...
+  else _dataOut >>= n;            // only shift if there are bits set
   PCF8575::write16(_dataOut);
 }
 
 void PCF8575::shiftLeft(const uint8_t n)
 {
   if ((n == 0) || (_dataOut == 0)) return;
-  if (n > 15) _dataOut = 0;           // shift 8++ clears all, valid...
-  if (_dataOut != 0) _dataOut <<= n;  // only shift if there are bits set
+  if (n > 15) _dataOut = 0;       // shift 8++ clears all, valid...
+  else _dataOut <<= n;            // only shift if there are bits set
   PCF8575::write16(_dataOut);
 }
 
 int PCF8575::lastError()
 {
   int e = _error;
-  _error = PCF8575_OK;
+  _error = PCF8575_OK;  // reset error after read, is this wise?
   return e;
 }
 
 void PCF8575::rotateRight(const uint8_t n)
 {
-  if ((n % 16) == 0) return;
   uint8_t r = n & 15;
+  if (r == 0) return;
   _dataOut = (_dataOut >> r) | (_dataOut << (15 - r));
   PCF8575::write16(_dataOut);
 }
 
 void PCF8575::rotateLeft(const uint8_t n)
 {
-  rotateRight(16- (n & 15));
+  rotateRight(16 - (n & 15));
 }
 
-void PCF8575::reverse() // quite fast
-{
-  uint8_t x = _dataOut;
-  x = (((x & 0xAAAA) >> 1) | ((x & 0x5555) << 1));
-  x = (((x & 0xCCCC) >> 2) | ((x & 0x3333) << 2));
-  x = (((x & 0xF0F0) >> 4) | ((x & 0x0F0F) << 4));
-  x = (((x & 0xFF00) >> 8) | ((x & 0x00FF) << 8));
+void PCF8575::reverse()   // quite fast
+{                                                     //     1 char === 1 bit
+  uint16_t x = _dataOut;                              // x = 0123456789ABCDEF 
+  x = (((x & 0xAAAA) >> 1) | ((x & 0x5555) << 1));    // x = 1032547698BADCFE
+  x = (((x & 0xCCCC) >> 2) | ((x & 0x3333) << 2));    // x = 32107654BA98FEDC
+  x = (((x & 0xF0F0) >> 4) | ((x & 0x0F0F) << 4));    // x = 76543210FEDCBA98
+  x = (x >> 8) | ( x << 8);                           // x = FEDCBA9876543210
   PCF8575::write16(x);
 }
 
 //added 0.1.07/08 Septillion
 uint16_t PCF8575::readButton16(const uint16_t mask)
 {
   uint16_t temp = _dataOut;
-  PCF8575::write16(mask | _dataOut); 
+  PCF8575::write16(mask | _dataOut);  // read only selected lines
   PCF8575::read16();
-  PCF8575::write16(temp);
+  PCF8575::write16(temp);             // restore
   return _dataIn;
 }
 

PCF8575.h

@@ -3,20 +3,23 @@
 //    FILE: PCF8575.h
 //  AUTHOR: Rob Tillaart
 //    DATE: 2020-07-20
-// VERSION: 0.0.2
+// VERSION: 0.0.3
 // PURPOSE: Arduino library for PCF8575 - 16 channel I2C IO expander
 //     URL: https://github.com/RobTillaart/PCF8575
 //
 // HISTORY:
-// based upon PCF8574 library
-//
 // see PCF8575.cpp file
 //
 
 #include "Arduino.h"
 #include "Wire.h"
 
-#define PCF8575_LIB_VERSION      "0.0.2"
+#define PCF8575_LIB_VERSION      "0.0.3"
+
+#ifndef PCF8575_INITIAL_VALUE
+#define PCF8575_INITIAL_VALUE    0xFFFF
+#endif
+
 
 #define PCF8575_OK               0x00
 #define PCF8575_PIN_ERROR        0x81
@@ -30,9 +33,10 @@ class PCF8575
   explicit PCF8575(const uint8_t deviceAddress);
 
 #if defined (ESP8266) || defined(ESP32)
-  void     begin(uint8_t sda, uint8_t scl, uint16_t val = 0xFFFF);
+  void     begin(uint8_t sda, uint8_t scl, uint16_t val = PCF8575_INITIAL_VALUE);
 #endif
-  void     begin(uint16_t val = 0xFFFF);
+  void     begin(uint16_t val = PCF8575_INITIAL_VALUE);
+  bool     isConnected();
 
   uint16_t read16();
   uint8_t  read(uint8_t pin);
@@ -48,7 +52,7 @@ class PCF8575
   uint8_t  readButton(const uint8_t pin);
   void     setButtonMask(uint16_t mask) { _buttonMask = mask; };
 
-    // rotate, shift, toggle, reverse expect all lines are output
+  // rotate, shift, toggle, reverse expect all lines are output
   void     toggle(const uint8_t pin);
   void     toggleMask(const uint16_t mask = 0xFFFF);    // default invertAll()
   void     shiftRight(const uint8_t n = 1);

README.md

@@ -22,12 +22,21 @@ The library allows to read and write both single pins or 16 pins at once.
 Furthermore some additional functions are implemented that are a little more
 playfull but still are useful.
 
+## I2C Clock
+
+Testing showed that the PCF8575 still works at 600 KHz and failed at 800 KHz.
+These values are outside the specs of the datasheet so they are not recommendend.
+However when performance is neede you can try to overclock the chip. 
 
 ## Interface
 
-- **PCF8575(deviceAddress)** Constructor with device address as parameter.
-- **begin(val = 0xFF)** set the initial value for the pins and masks.
-- **begin(sda, scl, val = 0xFFFF)** idem, for the ESP32 where one can choose the I2C pins
+**PCF8575_INITIAL_VALUE** is a define that can be set compile time or before
+the include of "pcf8575.h" to overrule the default value used with the 
+**begin()** call.
+
+- **PCF8575(deviceAddress)** Constructor with I2C device address as parameter.
+- **begin(val = PCF8575_INITIAL_VALUE)** set the initial value for the pins and masks.
+- **begin(sda, scl, val = PCF8575_INITIAL_VALUE)** idem, for the ESP32 where one can choose the I2C pins
 What needs to be added in the future is a parameter to choose another Wire interface
 as some processors have multiple hardware Wire interfaces.
 - **read16()** reads all 16 pins at once. This one does the actual reading.
@@ -52,6 +61,12 @@ Fills the lower lines with zero's.
 - **rotateLeft(n = 1)** rotates output channels to left, moving highest line to lowest line.
 - **reverse()** revers the "bit pattern" of the lines, high to low and vice versa.
 
+## Testing
+
+Testing the initial library is done by Colin Mackay (thanks!).
+
+Platforms used for testing include: Nano, ESP32 and Seeed Xiao
+
 
 ## Operation
 

keywords.txt

@@ -0,0 +1,32 @@
+# Syntax Coloring Map For PCF8575
+
+# Datatypes (KEYWORD1)
+PCF8575	KEYWORD1
+
+# Methods and Functions (KEYWORD2)
+begin	KEYWORD2
+isConnected	KEYWORD2
+
+read16	KEYWORD2
+read	KEYWORD2
+value	KEYWORD2
+
+write16	KEYWORD2
+write	KEYWORD2
+valueOut	KEYWORD2
+
+readButton16	KEYWORD2
+readButton	KEYWORD2
+setButtonMask	KEYWORD2
+
+toggle	KEYWORD2
+toggleMask	KEYWORD2
+shiftRight	KEYWORD2
+shiftLeft	KEYWORD2
+rotateRight	KEYWORD2
+rotateLeft	KEYWORD2
+reverse	KEYWORD2
+lastError	KEYWORD2
+
+# Constants (LITERAL1)
+

library.json

@@ -1,6 +1,6 @@
 {
   "name": "PCF8575",
-  "keywords": "I2C, PCF8575, 16 channel, IO, I/O, shift, rotate",
+  "keywords": "I2C, PCF8575, 16 channel, IO, I/O, shift, rotate, readButton, toggle, reverse",
   "description": "Arduino library for PCF8575 - 16 channel I2C IO expander, implements shift rotate.",
   "authors":
   [
@@ -15,7 +15,7 @@
     "type": "git",
     "url": "https://github.com/RobTillaart/PCF8575.git"
   },
-  "version":"0.0.2",
+  "version":"0.0.3",
   "frameworks": "arduino",
   "platforms": "*"
 }

library.properties

@@ -1,5 +1,5 @@
 name=PCF8575
-version=0.0.2
+version=0.0.3
 author=Rob Tillaart <rob.tillaart@gmail.com>
 maintainer=Rob Tillaart <rob.tillaart@gmail.com>
 sentence=Arduino library for PCF8575 - 16 channel I2C IO expander