From 90039d14d65584ba0a53906c031ed3cd8ea8e5f2 Mon Sep 17 00:00:00 2001
From: Rob Tillaart <rob.tillaart@gmail.com>
Date: Wed, 3 Jul 2024 10:42:51 +0200
Subject: [PATCH] refactor #78, redo #76

---
 ADS1X15.cpp  | 47 ++++++++++++++++++++++++++++-------------------
 ADS1X15.h    |  3 ++-
 CHANGELOG.md |  1 +
 README.md    |  7 ++++---
 4 files changed, 35 insertions(+), 23 deletions(-)

diff --git a/ADS1X15.cpp b/ADS1X15.cpp
index 87e0d96..c65d710 100644
--- a/ADS1X15.cpp
+++ b/ADS1X15.cpp
@@ -183,8 +183,8 @@ uint8_t ADS1X15::getGain()
     case ADS1X15_PGA_0_512V: return 8;
     case ADS1X15_PGA_0_256V: return 16;
   }
-  _err = ADS1X15_INVALID_GAIN;
-  return _err;
+  _error = ADS1X15_INVALID_GAIN;
+  return _error;
 }
 
 
@@ -219,8 +219,8 @@ float ADS1X15::getMaxVoltage()
     case ADS1X15_PGA_0_512V: return 0.512;
     case ADS1X15_PGA_0_256V: return 0.256;
   }
-  _err = ADS1X15_INVALID_VOLTAGE;
-  return _err;
+  _error = ADS1X15_INVALID_VOLTAGE;
+  return _error;
 }
 
 
@@ -242,8 +242,8 @@ uint8_t ADS1X15::getMode(void)
     case ADS1X15_MODE_CONTINUE: return 0;
     case ADS1X15_MODE_SINGLE:   return 1;
   }
-  _err = ADS1X15_INVALID_MODE;
-  return _err;
+  _error = ADS1X15_INVALID_MODE;
+  return _error;
 }
 
 
@@ -402,8 +402,8 @@ int16_t ADS1X15::getComparatorThresholdHigh()
 
 int8_t ADS1X15::getError()
 {
-  int8_t rv = _err;
-  _err = ADS1X15_OK;
+  int8_t rv = _error;
+  _error = ADS1X15_OK;
   return rv;
 }
 
@@ -455,10 +455,10 @@ int16_t ADS1X15::_readADC(uint16_t readmode)
     //  timeout == { 129, 65, 33, 17, 9, 5, 3, 2 }
     //  a few ms more than max conversion time.
     uint8_t timeOut = (128 >> (_datarate >> 5)) + 1;
-    while (isBusy()) 
+    while (isBusy())
     {
       yield();   //  wait for conversion; yield for ESP.
-      if ( (millis() - start) > timeOut) 
+      if ( (millis() - start) > timeOut)
       {
         return ADS1X15_ERROR_TIMEOUT;
       }
@@ -491,7 +491,7 @@ void ADS1X15::_requestADC(uint16_t readmode)
   _writeRegister(_address, ADS1X15_REG_CONFIG, config);
 
   //  remember last request type.
-    _lastRequest = readmode;
+  _lastRequest = readmode;
 }
 
 
@@ -501,7 +501,13 @@ bool ADS1X15::_writeRegister(uint8_t address, uint8_t reg, uint16_t value)
   _wire->write((uint8_t)reg);
   _wire->write((uint8_t)(value >> 8));
   _wire->write((uint8_t)(value & 0xFF));
-  return (_wire->endTransmission() == 0);
+  int rv = _wire->endTransmission();
+  if (rv != 0) 
+  {
+    _error =  ADS1X15_ERROR_I2C;
+    return false;
+  }
+  return true;
 }
 
 
@@ -509,15 +515,18 @@ uint16_t ADS1X15::_readRegister(uint8_t address, uint8_t reg)
 {
   _wire->beginTransmission(address);
   _wire->write(reg);
-  _wire->endTransmission();
-
-  int rv = _wire->requestFrom((int) address, (int) 2);
-  if (rv == 2)
+  int rv = _wire->endTransmission();
+  if (rv == 0) 
   {
-    uint16_t value = _wire->read() << 8;
-    value += _wire->read();
-    return value;
+    rv = _wire->requestFrom((int) address, (int) 2);
+    if (rv == 2)
+    {
+      uint16_t value = _wire->read() << 8;
+      value += _wire->read();
+      return value;
+    }
   }
+  _error =  ADS1X15_ERROR_I2C;
   return 0x0000;
 }
 
diff --git a/ADS1X15.h b/ADS1X15.h
index eea1244..601dacb 100644
--- a/ADS1X15.h
+++ b/ADS1X15.h
@@ -28,6 +28,7 @@
 #define ADS1X15_OK                        0
 #define ADS1X15_INVALID_VOLTAGE           -100
 #define ADS1X15_ERROR_TIMEOUT             -101
+#define ADS1X15_ERROR_I2C                 -102
 #define ADS1X15_INVALID_GAIN              0xFF
 #define ADS1X15_INVALID_MODE              0xFE
 
@@ -195,7 +196,7 @@ class ADS1X15
   void     _requestADC(uint16_t readmode);
   bool     _writeRegister(uint8_t address, uint8_t reg, uint16_t value);
   uint16_t _readRegister(uint8_t address, uint8_t reg);
-  int8_t   _err = ADS1X15_OK;
+  int8_t   _error = ADS1X15_OK;
 
   TwoWire*  _wire;
   uint32_t  _clockSpeed = 0;
diff --git a/CHANGELOG.md b/CHANGELOG.md
index a517ac4..98afd75 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ## [0.4.5] - 2024-07-03
 - Fix #78, prevent infinite loop. (Thanks to devmirek).
 - Fix #76 (again), update readme.md Comparator Polarity.
+- add ADS1X15_ERROR_I2C, communication error.
 - add minimal section in readme.md about error codes.
 - minor edits.
 
diff --git a/README.md b/README.md
index 4be6192..9f4f020 100644
--- a/README.md
+++ b/README.md
@@ -597,7 +597,8 @@ This is read and reset by **getError()**
 |:-------:|:-------------------------:|:-------------:|
 |      0  |  ADS1X15_OK               | idem.
 |   -100  |  ADS1X15_INVALID_VOLTAGE  | getMaxVoltage()
-|   -101  |  ADS1X15_ERROR_TIMEOUT    | readADC() device failure.
+|   -101  |  ADS1X15_ERROR_TIMEOUT    | readADC() device did not respond in time.
+|   -102  |  ADS1X15_ERROR_I2C        | I2C communication failure.
 |   0xFF  |  ADS1X15_INVALID_GAIN     | getGain() 
 |   0xFE  |  ADS1X15_INVALID_MODE     | getMode()
 
@@ -614,13 +615,13 @@ This is read and reset by **getError()**
 - Remove the experimental **getWireClock()** as this is not really a library function
   but a responsibility of the I2C library.
 - Investigate ADS1118 library which should be a similar SPI based ADC.
+- improve error handling
+  - refactor values to be more logic.
 
 #### Could
 
-- More examples
 - SMB alert command (00011001) on I2C bus?
 - Sync code order .h / .cpp
-- more error handling?
 
 #### Wont (unless requested)