GY-63_MS5611/libraries/DS2438

DS2438

Arduino Library for the DS2438 1-wire battery monitor.

Description

The DS2438 is a very experimental library for the DS2438 battery management sensor.

The library is not tested yet as I have no hardware (breakout board). So for the moment the library is written based upon the datasheet and provided as is.

The device supports the following functionality.

• voltage measurement
• temperature measurement
• current measurement.
• 40 bytes non-volatile EEPROM memory
• Elapsed time meter in binary format

This library supports only one DS2438 per Arduino / MCU pin.

As always, feedback is welcome.

Hardware pins

Need to find a breakout.

See datasheet for details

                   DS2438
              +------------------+
              | 1  GND           |
              | 2  Vsense+       |
              | 3  Vsense-       |
              | 4  VAD           |
              | 5  VDD           |
              | 6  NC            |
              | 7  NC            |
              | 8  DQ            |
              +------------------+

Pin	Description	Connect to
DQ	Data In/Out	processor
VAD	General A/D input
VSENS+	Battery current monitor input (+)	Battery
VSENS-	Battery current monitor input (-)	Battery
VDD	Power Supply (2.4V to 10.0V)	+5V
GND	Ground	processor
NC	No connect	-

Related

• https://github.com/RobTillaart/DS2438
• https://github.com/RobTillaart/Temperature (conversions)

Interface

#include "DS2438.h"

Constructor

• DS2438(OneWire * ow) constructor needs a reference to OneWire object.
• bool begin(uint8_t retries = 3) resets oneWire. 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.

Temperature and voltage

• float readTemperature() read temperature from device. Units = Celsius.
• float getTemperature() get the last read temperature.
• float readVDD() read voltage VDD from device. Units = Volts.
• float getVDD() get the last read voltage VDD.
• float readVAD() read voltage VAD. Units = Volts.
• float getVAD() get the last read voltage VAD.

Current

See datasheet for details. Choice of the resistor determines the working range / accuracy.

• void setResistor(float resistor = 0.01) set the shunt resistor in OHM. This allows a sort of tuning/calibration.
• void enableCurrentMeasurement() set IAD bit, see datasheet. Starts the background measurement of the current. Takes ~28 milliseconds for a measurement. Must be called before readCurrent will work.
• void disableCurrentMeasurement() clear IAD bit, see datasheet. Stops the background measurement of the current.
• float readCurrent() read current from device.
• float getCurrent() get last read current.
• void writeCurrentOffset(int value)
• int readCurrentOffset()

ICA

See datasheet for details.

• ICA = Integrated Current Accumulator.

• float readRemaining()

• void writeThreshold(uint8_t value)

• uint8_t readThreshold()

Only 4 values possible.

value	Threshold
0x00	None (default)
0x40	±2 LSB
0x80	±4 LSB
0xC0	±8 LSB

Time

From datasheet:

The elapsed time meter (ETM) is a 4-byte binary counter with 1-second resolution. The ETM can accumulate 136 years of seconds before rolling over. Time/date is represented by the number of seconds since a reference point, which is determined by the user. For example, 12:00 A.M., January 1, 1970 could be used as a reference point.

• void writeElapsedTimeMeter(uint32_t value) value in seconds.
• uint32_t readElapsedTimeMeter() returns current time in seconds.
• uint32_t readDisconnectTime() returns last disconnect timestamp.
• uint32_t readEndOfChargeTime() returns last end of charging timestamp.

EEPROM

Valid addresses are 0..35 if CCA/DCA is enabled, 0..39 otherwise.

• bool writeEEPROM(uint8_t address, uint8_t value) write a byte to EEPROM address.
• uint8_t readEEPROM(uint8_t address) read the byte from EEPROM address.

CCA DCA

See datasheet for details.

• CCA = Charging Current Accumulator

• DCA = Discharge Current Accumulator

• void enableCCA() also enables DCA.

• void disableCCA()

• float readCCA() Does not check if enabled.

• float readDCA() Does not check if enabled.

Configuration register

See datasheet for details.

• void setConfigBit(uint8_t bit) bit = 0..3
• void clearConfigBit(uint8_t bit) bit = 0..3
• uint8_t getConfigRegister() returns configuration and status bits.

bit	name	def	description
0	IAD	1	Current A/D Control bit.
1	CA	1	Current Accumulator Configuration bit.
2	EE	1	Current Accumulator Shadow Selector bit.
3	AD	1	Voltage A/D Input Select bit. 1 = VDD, 0 = VAD.
4	TB	0	Temperature Busy Flag.
5	NVB	0	Non Volatile Memory Busy Flag.
6	ADB	0	A/D Converter Busy Flag.
7	x	x	don't care.

Operation

This library supports only one DS2438 per Arduino / MCU pin.

Future

Must

• Improve documentation (a lot).
• test with hardware or simulator?.
• examples for testing.

Should

• implement CRC

Could

only after testing and code works.

• getters,
  • remove? == user responibility?
  • renaming: getVDD() vs getLastVDD? et al.
• unit tests?
  • possible?
• async interface for both T and V.
• optimize the code.
  • cache registers?
• improve magic masks and numbers
• performance test.
• getAddress() ?
• debugging
• error handling.
• copy snapshot to EEPROM(page)
  • copies page 0 to EEPROM page 0..4

Wont

Support

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Thank you,