4.1.11 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.

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

Experimental Procedures¶

Step 1: Build the circuit.

Step 2: Go to the folder of the code.

cd ~/raphael-kit/python/

Step 3: Run the executable file.

sudo python3 4.1.11_BatteryIndicator.py

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).

Code

Note

You can Modify/Reset/Copy/Run/Stop the code below. But before that, you need to go to source code path like raphael-kit/python. After modifying the code, you can run it directly to see the effect.

import RPi.GPIO as GPIO
import ADC0834
import time

ledPins = [25, 12, 16, 20, 21, 5, 6, 13, 19, 26]

def setup():
    GPIO.setmode(GPIO.BCM)
    ADC0834.setup()
    for i in ledPins:
        GPIO.setup(i, GPIO.OUT)
        GPIO.output(i, GPIO.HIGH)

def LedBarGraph(value):
    for i in ledPins:
        GPIO.output(i,GPIO.HIGH)
    for i in range(value):
        GPIO.output(ledPins[i],GPIO.LOW)

def destroy():
    GPIO.cleanup()

def loop():
    while True:
        analogVal = ADC0834.getResult()
        LedBarGraph(int(analogVal/25))

if __name__ == '__main__':
    setup()
    try:
        loop()
    except KeyboardInterrupt: # When 'Ctrl+C' is pressed, the program destroy() will be executed.
        destroy()

Code Explanation

def LedBarGraph(value):
    for i in ledPins:
        GPIO.output(i,GPIO.HIGH)
    for i in range(value):
        GPIO.output(ledPins[i],GPIO.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.

def loop():
    while True:
        analogVal = ADC0834.getResult()
        LedBarGraph(int(analogVal/25))

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.”