Grove - Coulomb Counter 3.3V to 5V (LTC2941)

The coulomb (symbol: C) is the International System of Units (SI) unit of electric charge.It is the charge (symbol: Q or q) transported by a constant current of one ampere in one second:1C=1A•1s. A Coulomb Counter is a device to measure the current that your devices or sensors is using.

The Grove - Coulomb Counter 3.3V to 5V (LTC2941) is based on LTC2941, its operating range is perfectly suited for single-cell Li-Ion batteries. A precision coulomb counter integrates current through a sense resistor between the battery’s positive terminal and the load or charger. This module measures the amount of amp-hours have been used, if you use a fully charged battery, you can test the amount of battery you have used, the remaining percentage, just like the remaining battery shown in your phone. Vice versa, if you are changring a battery, you can use this module to monitor the charging process.

Features

Indicates Accumulated Battery Charge and Discharge
High Accuracy Analog Integration
1% Charge Accuracy
SMBus/I2C Interface

Specification

Item	Value
Operating Voltage	2.7V to 5.5V
Operating Temperature	0℃ to +70℃
Accuracy	±2ppm from 0°C to +40°C
Interface	I2C
I2C Address	0x64

Typical Applications

Low Power Handheld Products
Cellular Phones
MP3 Player
Cameras
GPS

Hardware Overview

Pin Out

Overview

Danger

Both 3 and 4 are power input interfaces, please selecte one as the power input, do not use two at the same time, and the voltage can not exceed 5V, otherwise the module may be damaged.

Grove Interface

This module communicate with the control board via I2C interface:

GND: Power pin, connect to the systerm GND
VCC: Power pin, connect to the 5V or 3.3V, power supply for this module. SDA: Signal pin, I2C serial data
SCL: Signal pin, I2C serial clock

OUT

Power output, connect to the load or the charger.

+: Power output Positive electrode
-: Power output negative electrode

caution

Do not connect directly to inductive loads, such as motors or servos, or the chip may be damaged due to ripple caused by inductive loads.

Power input, power supply for the OUT

+: Power input Positive electrode
-: Power input negative electrode

caution

If you use the I2C Scanner to scan the device I2C ID, you have to supply 3.3v/5v to IN terminal.

Battery Input

Battery Input, support 3.7-4.2v Li-PO battery, Jst2.0(2 pin-2.0mm), power supply for the OUT

+: Battery input Positive electrode
-: Battery input negative electrode

Alarm Pin

Connect to the AL/CC pin of LTC2941, alert output or charge complete input. The LTC2941 do support alert function, and we reserved the relevant hardware pins for you, however the software we provide do not support this function. So, you need to work with the software part yourself if you need this part.

Platforms Supported

Arduino	Raspberry Pi

caution

The platforms mentioned above as supported is/are an indication of the module's software or theoritical compatibility. We only provide software library or code examples for Arduino platform in most cases. It is not possible to provide software library / demo code for all possible MCU platforms. Hence, users have to write their own software library.

Getting Started

Play With Arduino

Hardware

Materials required

Seeeduino V4.2	Base Shield	Grove - Coulomb Counter 3.3V to 5V (LTC2941)

Get One Now	Get One Now	Get One Now

note

1 Please plug the USB cable gently, otherwise you may damage the port. Please use the USB cable with 4 wires inside, the 2 wires cable can't transfer data. If you are not sure about the wire you have, you can click here to buy

2 Each Grove module comes with a Grove cable when you buy. In case you lose the Grove cable, you can click here to buy.

Step 1. Plug the load or charger into the port OUT.
Step 2. Plug the battery into the JST port or plug other power source into port IN.
Step 3. Plug the Grove - Coulomb Counter 3.3V to 5V (LTC2941) to port I2C of Grove-Base Shield.
Step 4. Plug Grove - Base Shield into Seeeduino.
Step 5. Connect Seeeduino to PC via a USB cable.

note

If we don't have Grove Base Shield, We also can directly connect this module to Seeeduino as below.

Seeeduino	Grove Cable	Grove - Coulomb Counter 3.3V to 5V (LTC2941)
GND	Black	GND
5V or 3.3V	Red	VCC
SDA	White	SDA
SCL	Yellow	SCL

Software

caution

If this is the first time you work with Arduino, we strongly recommend you to see Getting Started with Arduino before the start.

Step 1. Download the Seeed_LTC2941 Library from Github.
Step 2. Refer to How to install library to install library for Arduino.
Step 3. Restart the Arduino IDE. Open the example, you can open it in the following three ways：
1. Open it directly in the Arduino IDE via the path: File --> Examples --> Grove - Coulomb Counter for 3.3V to 5V(LTC2941) --> battery_power.
  battery_power: This demo will show you the electric charge data in the unit C and mAh, 1mAh=3.6C, as well as the remaining battery in percentage.
  current_expend: This demo will show you how much power you are consuming.
2. Open it in your computer by click the battery_power.ino which you can find in the folder XXXX\Arduino\libraries\Seeed_LTC2941-master\examples\battery_power, XXXX is the location you installed the Arduino IDE.
3. Or, you can just click the icon in upper right corner of the code block to copy the following code into a new sketch in the Arduino IDE.

#include "LTC2941.h"

#ifdef ARDUINO_SAMD_VARIANT_COMPLIANCE
  #define SERIAL SerialUSB
#else
  #define SERIAL Serial
#endif

float coulomb = 0, mAh = 0, percent = 0;

void setup(void)
{
    Wire.begin();
    
    SERIAL.begin(115200);
    while(!SERIAL.available());
    
    SERIAL.println("LTC2941 Raw Data");
    
    ltc2941.initialize();
    ltc2941.setBatteryFullMAh(400);
}

void loop(void)
{
    coulomb = ltc2941.getCoulombs();
    mAh = ltc2941.getmAh();
    percent = ltc2941.getPercent();
    
    SERIAL.print(coulomb);
    SERIAL.print("C,");
    SERIAL.print(mAh);
    SERIAL.print("mAh,");
    SERIAL.print(percent);
    SERIAL.print("%");
    
    SERIAL.println();
    
    delay(1000);
}

caution

The library file may be updated. This code may not be applicable to the updated library file, so we recommend that you use the first two methods.

Step 4. Upload the demo. If you do not know how to upload the code, please check How to upload code.
Step 5. Open the Serial Monitor of Arduino IDE by click Tool-> Serial Monitor. Or tap the ctrl+shift+m key at the same time. Set the baud rate to 115200.

success

If every thing goes well, when you open the Serial Monitor and tap any key the press the send button , it may show as below:

LTC2941 Raw Data
96C,399.99mAh,100.00%
96C,399.99mAh,100.00%
96C,399.99mAh,100.00%
96C,399.99mAh,100.00%
92C,399.98mAh,99.99%

Function description

In the demo, we use a 400mAh battery, so you can see the results 1439.96mC,399.99mAh,100.00%. The percentage of remaining battery is valid only after you set the battery capacity. You can change the battery capacity at the code line 21,

ltc2941.setBatteryFullMAh(400); // set the battery capacity here

What's more, every time you re-open the serial port, or re-power the control board, the data will be reset to 100.00%. So, there still a lot work to do if you want to use it in your phone :D

Schematic Online Viewer

Resources

[Zip] Grove - Coulomb Counter 3.3V to 5V (LTC2941) Eagle Files
[Zip] Seeed LTC2941 Library
[PDF] Datasheet LTC2941

Project

This is the introduction Video of this product, simple demos, you can have a try.

Tech Support

Please do not hesitate to submit the issue into our forum

Features​

Specification​

Typical Applications​

Hardware Overview​

Pin Out​

Platforms Supported​

Getting Started​

Play With Arduino​

Hardware​

Software​

Function description​

Schematic Online Viewer​

Resources​

Project​

Tech Support​

Features

Specification

Typical Applications

Hardware Overview

Pin Out

Platforms Supported

Getting Started

Play With Arduino

Hardware

Software

Function description

Schematic Online Viewer

Resources

Project

Tech Support