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3.1.5 Battery Indicator

Introduction

In this project, we will make a battery indicator device that can visually display the battery level on the LED Bargraph.

Required Components

In this project, we need the following components.

../_images/list_Battery_Indicator.png

It’s definitely convenient to buy a whole kit, here’s the link:

Name

ITEMS IN THIS KIT

LINK

Raphael Kit

337

Raphael Kit

You can also buy them separately from the links below.

COMPONENT INTRODUCTION

PURCHASE LINK

GPIO Extension Board

BUY

Breadboard

BUY

Jumper Wires

BUY

Resistor

BUY

LED Bar Graph

-

ADC0834

-

Schematic Diagram

T-Board Name

physical

wiringPi

BCM

GPIO17

Pin 11

0

17

GPIO18

Pin 12

1

18

GPIO27

Pin 13

2

27

GPIO25

Pin 22

6

25

GPIO12

Pin 32

26

12

GPIO16

Pin 36

27

16

GPIO20

Pin 38

28

20

GPIO21

Pin 40

29

21

GPIO5

Pin 29

21

5

GPIO6

Pin 31

22

6

GPIO13

Pin 33

23

13

GPIO19

Pin 35

24

19

GPIO26

Pin 37

25

26
../_images/Schematic_three_one5.png

Experimental Procedures

Step 1: Build the circuit.

../_images/image248.png

Step 2: Go to the folder of the code.

cd ~/raphael-kit/c/3.1.5/

Step 3: Compile the code.

gcc 3.1.5_BatteryIndicator.c -lwiringPi

Step 4: Run the executable file.

sudo ./a.out

After the program runs, give the 3rd pin of ADC0834 and the GND a lead-out wire separately and then lead them to the two poles of a battery separately. You can see the corresponding LED on the LED Bargraph is lit up to display the power level (measuring range: 0-5V).

Note

If it does not work after running, or there is an error prompt: "wiringPi.h: No such file or directory", please refer to Install and Check the WiringPi.

Code Explanation

void LedBarGraph(int value){
    for(int i=0;i<10;i++){
        digitalWrite(pins[i],HIGH);
    }
    for(int i=0;i<value;i++){
        digitalWrite(pins[i],LOW);
    }
}

This function works for controlling the turning on or off of the 10 LEDs on the LED Bargraph. We give these 10 LEDs high levels to let they are off at first, then decide how many LEDs are lit up by changing the received analog value.

int main(void)
{
    uchar analogVal;
    if(wiringPiSetup() == -1){ //when initialize wiring failed,print messageto screen
        printf("setup wiringPi failed !");
        return 1;
    }
    pinMode(ADC_CS,  OUTPUT);
    pinMode(ADC_CLK, OUTPUT);
    for(int i=0;i<10;i++){       //make led pins' mode is output
        pinMode(pins[i], OUTPUT);
        digitalWrite(pins[i],HIGH);
    }
    while(1){
        analogVal = get_ADC_Result(0);
        LedBarGraph(analogVal/25);
        delay(100);
    }
    return 0;
}

analogVal produces values (0-255) with varying voltage values (0-5V), ex., if a 3V is detected on a battery, the corresponding value 152 is displayed on the voltmeter.

The 10 LEDs on the LED Bargraph are used to display the analogVal readings. 255/10=25, so every 25 the analog value increases, one more LED turns on, ex., if “analogVal=150 (about 3V), there are 6 LEDs turning on.”

Phenomenon Picture

../_images/image249.jpeg