0.2.1 DS2438

Author: RobTillaart

libraries/DS2438/CHANGELOG.md

@@ -6,6 +6,14 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
 
+## [0.2.1] - 2026-02-05
+- fix #7, add isDS2438()
+- fix readRemaining();
+- update examples
+- add performance example
+- update readme.md
+- minor edits
+
 ## [0.2.0] - 2026-02-05
 - fix address bug in read/writeEEPROM()
 - fix #5, improve demo sketch

libraries/DS2438/DS2438.cpp

@@ -1,7 +1,7 @@
 //
 //    FILE: DS2438.cpp
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.2.0
+// VERSION: 0.2.1
 //    DATE: 2023-07-28
 // PURPOSE: Arduino Library for DS2438 battery monitor
 //     URL: https://github.com/RobTillaart/DS2438
@@ -68,6 +68,14 @@ bool DS2438::isConnected(uint8_t retries)
   return _addressFound;
 }
 
+bool DS2438::isDS2438()
+{
+  if (_addressFound || isConnected(3))
+  {
+    return (_address[0] == 0x26);
+  }
+  return false;
+}
 
 ///////////////////////////////////////////////////////////
 //
@@ -86,7 +94,7 @@ float DS2438::readTemperature()
   readScratchPad(0);
 
   //             sign    MSB               LSB         step      >> 3
- _temperature = (int(_scratchPad[2]) * 256 + _scratchPad[1]) * 0.03125 * 0.125;
+ _temperature = (int(_scratchPad[2]) * 256 + _scratchPad[1]) * (0.03125f * 0.125f);
 
   return _temperature;
 }
@@ -127,7 +135,7 @@ float DS2438::readVDD()
   readScratchPad(DS2438_PAGE_CORE);
 
   //  10 mV resolution
-  _vdd = ((_scratchPad[4] & 0x03) * 256 + _scratchPad[3]) * 0.01;
+  _vdd = ((_scratchPad[4] & 0x03) * 256 + _scratchPad[3]) * 0.01f;
 
   //  convert current in same call?!
 
@@ -152,7 +160,7 @@ float DS2438::readVAD()
   readScratchPad(DS2438_PAGE_CORE);
 
   //  10 mV resolution
-  _vad = ((_scratchPad[4] & 0x03) * 256 + _scratchPad[3]) * 0.01;
+  _vad = ((_scratchPad[4] & 0x03) * 256 + _scratchPad[3]) * 0.01f;
 
   //  convert current in same call?!
 
@@ -172,8 +180,8 @@ float DS2438::getVAD()
 //
 void DS2438::setResistor(float resistor)
 {
-  _inverseR = 1.0 / (4096.0 * resistor);
-  _RICA     = 1.0 / (2048.0 * resistor);
+  _inverseR = 1.0f / (4096.0f * resistor);
+  _RICA     = 1.0f / (2048.0f * resistor);
 }
 
 
@@ -245,9 +253,9 @@ float DS2438::readRemaining()
 {
   //  datasheet p.7
   readScratchPad(DS2438_PAGE_ETM_ICA_OFFSET);
-  //  factor 2.0 from optimization (need to explain this factor)
   //  Remaining Capacity = ICA / (2048 * RSENS)
-  float remaining = _scratchPad[4] / _RICA;  //   mAhr
+  //  setResistor() :  _RICA = 1.0/(2048 * Rsens);
+  float remaining = _scratchPad[4] * _RICA;  //   mAhr
   return remaining;
 }
 
@@ -391,15 +399,15 @@ float DS2438::readCCA()
   //  datasheet p.8 + 16
   readScratchPad(DS2438_PAGE_CCA_DCA);
   uint16_t raw = (_scratchPad[5] * 256 + _scratchPad[4]);
-  return raw * 15.625;
+  return raw * 15.625f;
 }
 
 float DS2438::readDCA()
 {
   //  datasheet p.8 + 16
   readScratchPad(DS2438_PAGE_CCA_DCA);
   uint16_t raw = (_scratchPad[7] * 256 + _scratchPad[6]);
-  return raw * 15.625;
+  return raw * 15.625f;
 }
 
 bool DS2438::setCCA(float CCA)
@@ -408,7 +416,7 @@ bool DS2438::setCCA(float CCA)
   if (CCA < 0) return false;
    clearConfigBit(DS2438_CONFIG_IAD);
   readScratchPad(DS2438_PAGE_CCA_DCA);
-  uint16_t tmp = round(CCA / 15.625);
+  uint16_t tmp = round(CCA * (1.0f / 15.625f));
   _scratchPad[4] = tmp & 0xFF;
   _scratchPad[5] = tmp >> 8;
   writeScratchPad(DS2438_PAGE_CCA_DCA);
@@ -423,7 +431,7 @@ bool DS2438::setDCA(float DCA)
   if (DCA < 0) return false;
   clearConfigBit(DS2438_CONFIG_IAD);
   readScratchPad(DS2438_PAGE_CCA_DCA);
-  uint16_t tmp = round(DCA / 15.625);
+  uint16_t tmp = round(DCA * (1.0f / 15.625f));
   _scratchPad[6] = tmp & 0xFF;
   _scratchPad[7] = tmp >> 8;
   writeScratchPad(DS2438_PAGE_CCA_DCA);
@@ -453,7 +461,7 @@ void DS2438::resetAccumulators()
 //
 void DS2438::setConfigBit(uint8_t bit)
 {
-  if (bit > 3) return;
+  if (bit > DS2438_CONFIG_AD) return;
   uint8_t mask = (0x01 << bit);
   readScratchPad(DS2438_PAGE_CORE);
   if ((_scratchPad[0] & mask) == mask) return;  //  already 1
@@ -463,7 +471,7 @@ void DS2438::setConfigBit(uint8_t bit)
 
 void DS2438::clearConfigBit(uint8_t bit)
 {
-  if (bit > 3) return;
+  if (bit > DS2438_CONFIG_AD) return;
   uint8_t mask = (0x01 << bit);
   readScratchPad(DS2438_PAGE_CORE);
   if ((_scratchPad[0] & mask) == 0x00) return;  //  already 0
@@ -515,7 +523,12 @@ void DS2438::readScratchPad(uint8_t page)
   _oneWire->write(DS2438_READ_SCRATCH, 0);
   _oneWire->write(page, 0);
   for (uint8_t i = 0; i < 8; i++) _scratchPad[i] = _oneWire->read();
-  //  skip crc for now.
+  //  skip CRC for now
+  //  - update loop to 9
+  //  - change return type
+  //  - set error flag.
+  //  return _oneWire->crc8(_scratchPad, 8) != _scratchPad[8]);
+  return;
 }
 
 
@@ -527,6 +540,7 @@ void DS2438::writeScratchPad(uint8_t page)
   _oneWire->write(DS2438_WRITE_SCRATCH, 0);
   _oneWire->write(page, 0);
   for (uint8_t i = 0; i < 8; i++) _oneWire->write(_scratchPad[i], 0);
+  //  no CRC when writing.
   _oneWire->reset();
   _oneWire->select(_address);
   _oneWire->write(DS2438_COPY_SCRATCH, 0);

libraries/DS2438/DS2438.h

@@ -2,22 +2,20 @@
 //
 //    FILE: DS2438.h
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.2.0
+// VERSION: 0.2.1
 //    DATE: 2023-07-28
 // PURPOSE: Arduino Library for DS2438 battery monitor
 //     URL: https://github.com/RobTillaart/DS2438
 //
-//                    DS2438
-//               +------------------+
-//               | 1  GND           |
-//               | 2  Vsense+       |
-//               | 3  Vsense-       |
-//               | 4  VAD           |
-//               | 5  VDD           |
-//               | 6  NC            |
-//               | 7  NC            |
-//               | 8  DQ            |
-//               +------------------+
+//
+//                       DS2438
+//             +-----------------------+
+//             | 1  GND           DQ 8 |
+//             | 2  Vsense+       NC 7 |
+//             | 3  Vsense-       NC 6 |
+//             | 4  VAD          VDD 5 |
+//             +-----------------------+
+//
 //
 //  |  Pin     |  Description                        |  Connect to  |
 //  |:--------:|:------------------------------------|:-------------|
@@ -33,7 +31,7 @@
 #include "Arduino.h"
 #include "OneWire.h"
 
-#define DS2438_LIB_VERSION        (F("0.2.0"))
+#define DS2438_LIB_VERSION        (F("0.2.1"))
 
 #define DS2438_INVALID             -999
 
@@ -55,7 +53,7 @@ class DS2438
 
   bool     begin(uint8_t retries = 3);
   bool     isConnected(uint8_t retries = 3);
-
+  bool     isDS2438();
 
   //  TEMPERATURE
   //  unit is degrees Celsius

libraries/DS2438/README.md

@@ -20,17 +20,18 @@ Arduino Library for the DS2438 1-wire battery monitor.
 
 The DS2438 is a experimental library for the DS2438 battery management sensor.
 
-The library is not tested by me in detail as I have no hardware (breakout board).
-So for the moment the library is written based upon the datasheet and provided as is.
-That said, the library is working (see e.g. #5) but use it with care as it is still
-work in progress.
+The library is tested in #5 and seems to work OK, but use it with care as 
+it is still work in progress.
+As I have no hardware == breakout board (yet) I cannot tests.
 
 The device supports the following functionality.
 - voltage measurement
 - temperature measurement
 - current measurement.
-- 40 bytes non-volatile EEPROM memory
+- 40 bytes non-volatile EEPROM memory (use only 36 see below)
 - Elapsed time meter in binary format
+- current accumulators
+- test deviceType
 
 This library supports only one DS2438 per Arduino / MCU pin.
 
@@ -40,7 +41,8 @@ As always, feedback is welcome.
 ### 0.2.0 Breaking Change
 
 The 0.2.0 version fixes a bug in the EEPROM that affects the proper working
-of the device. (See issue 5).
+of the device. (See issue 5). Furthermore there are many other fixes and
+enhancements.
 
 Versions before 0.2.0 are therefore obsolete.
 
@@ -52,17 +54,13 @@ Need to find a breakout.
 See datasheet for details for a measurement schema.
 
 ```
-                   DS2438
-              +------------------+
-              | 1  GND           |
-              | 2  Vsense+       |
-              | 3  Vsense-       |
-              | 4  VAD           |
-              | 5  VDD           |
-              | 6  NC            |
-              | 7  NC            |
-              | 8  DQ            |
-              +------------------+
+                     DS2438
+           +-----------------------+
+           | 1  GND           DQ 8 |
+           | 2  Vsense+       NC 7 |
+           | 3  Vsense-       NC 6 |
+           | 4  VAD          VDD 5 |
+           +-----------------------+
 ```
 
 |  Pin     |  Description                        |  Connect to  |
@@ -73,7 +71,7 @@ See datasheet for details for a measurement schema.
 |  VSENS-  |  Battery current monitor input (-)  |  Battery     |
 |  VDD     |  Power Supply (2.4V to 10.0V)       |  +5V         |
 |  GND     |  Ground                             |  processor   |
-|  NC      |  No connect                         |  -           |
+|  NC      |  No connected                       |  -           |
 
 
 ### Related
@@ -101,6 +99,9 @@ Returns true if address / device is found and all is OK.
 There will be a number of retries to connect, default 3.
 - **bool isConnected(uint8_t retries = 3)** Returns true if address / device is found.
 There will be a number of retries to connect, default 3.
+- **bool isDS2438()** returns true if the device type == 0x26 which indicates
+an DS2438. Returns false if no device seen or other type.
+
 
 ### Temperature
 
@@ -247,14 +248,11 @@ This library supports only one DS2438 per Arduino / MCU pin.
 
 #### Must
 
-- Improve documentation (a lot).
-- test with hardware or simulator?.
-- examples for testing.
+- improve documentation
 
 #### Should
 
-- implement CRC
-- add device type check
+- add real live examples
 
 #### Could
 
@@ -269,13 +267,13 @@ only after testing and code works.
 - optimize the code.
   - cache registers?
 - improve magic masks and numbers
-- performance test.
 - getAddress() ?
-- debugging
 - error handling.
 - copy snapshot to EEPROM(page) -> datasheet p.8 EE bit.
   - copies page 0 to EEPROM page 0..4
-
+- enable CRC in readScratchPad() 
+  - performance penalty
+  - failing CRC must be handled otherwise no added value.
 
 #### Wont
 

libraries/DS2438/examples/DS2438_demo/DS2438_demo.ino

@@ -25,7 +25,14 @@ void setup()
 
   bm.begin();
   Serial.println(bm.isConnected());
-
+  if (!bm.isDS2438())
+  {
+    Serial.print("Pin ");
+    Serial.print(ONE_WIRE_BUS);
+    Serial.println(" has no DS2438 attached.");
+    Serial.println("Check connections and restart.");
+    while(1);
+  }
 
   Serial.println("\nTemperature");
   bm.readTemperature();
@@ -48,6 +55,7 @@ void setup()
   delay(30);
   bm.readCurrent();
   Serial.println(bm.getCurrent());
+  Serial.println(bm.readCurrentOffset());
 
 
   Serial.println("\nTime");
@@ -57,7 +65,8 @@ void setup()
 
   Serial.println("\nThreshold");
   Serial.println(bm.readThreshold());
-
+  Serial.println("Remaining: ");
+  Serial.println(bm.readRemaining());
 
   Serial.println("\nCCA/DCA");
   Serial.println("  Charge: ");
@@ -66,6 +75,8 @@ void setup()
   Serial.println(bm.readDCA());
   Serial.println("    Delta: ");
   Serial.println(bm.readCCA() - bm.readDCA());
+  Serial.println("Remaining: ");
+  Serial.println(bm.readRemaining());
 
 
   Serial.println("\nEEPROM");