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Table of Contents

Introduction

This project uses one of the analog to digital converter (ADC) channels on the TINKERplate to measure and evaluate the capacity of a standard 1.5V alkaline battery. It then sends that information to the 8 channel LED strip that is included with the TINKERkit.

Required Parts

This project uses a few items from the TINKERkit:

the TINKERkit board connected tot the Raspberry Pi
the mini breadboard
nine male to male jumper wires
the 74HCT125 integrated circuit
the eight channel RGB LED strip

Steps

Assembly

Gather the materials above and connect everything together as shown in the diagram below:

When testing, place the red wire pn the positive terminal and the black wire on the negative terminal.

Code

Enter the following program into Thonny or copy the code below into you Home folder on your Raspberry Pi. The estimaed battery capacity will control how many LEDs are turned on. In addition, their colors will be set to indicate whether they are in the GOOD, OK, or BAD zone. The BAD zone is the bottom 4 LEDs which will be red. The OK zone will be two yellow LEDs in positions 5 and 6. And the GOOD zone will be the two green LEDs in positions 7 and 8.

For downloading:

import piplates.TINKERplate as TINK
import time

#create battery state thresholds
VL=1.2
VH=1.4

TINK.setDEFAULTS(0)
TINK.setMODE(0,1,'rgbled')  #set Digital I/O port to display Neopixels

red=[255,0,0]   #define the red color mix
yel=[255,255,0] #define the yellow color mix
grn=[0,255,0]   #define the green color mix
off=[0,0,0]     #define an off LED
blank=off+off+off+off+off+off+off+off   #create a set of OFF LEDs
strip=red+red+red+red+yel+yel+grn+grn   #create the battery status lights
while(True):
    bat=TINK.getADC(0,1)            #read analog channel 1
    #scale the data to an integer in the range of 0 through 7
    temp=bat-0.8    #we will only look at the range from 0.8 volts to 1.6
    if (temp<0):
        index=0     #if the measured voltage is negative, set index to 0
    else:           #otherwise, convert the voltage to a list index
        index=int(temp*10)
        if (index>7):   #limit the maximum index to 7
            index=7
    batstrip=strip[0:3*(index+1)]+blank[0:3*(8-index)]  #assembled string
    TINK.setRGBSTRING(0,1,batstrip) #send string data to TINKERplate
    time.sleep(.5)                  #delay and repeat

import piplates.TINKERplate as TINK

import time

#create battery state thresholds

VL=1.2

VH=1.4

TINK.setDEFAULTS(0)

TINK.setMODE(0,1,'rgbled') #set Digital I/O port to display Neopixels

red=[255,0,0] #define the red color mix

yel=[255,255,0] #define the yellow color mix

grn=[0,255,0] #define the green color mix

off=[0,0,0] #define an off LED

blank=off+off+off+off+off+off+off+off #create a set of OFF LEDs

strip=red+red+red+red+yel+yel+grn+grn #create the battery status lights

while(True):

bat=TINK.getADC(0,1) #read analog channel 1

#scale the data to an integer in the range of 0 through 7

temp=bat-0.8 #we will only look at the range from 0.8 volts to 1.6

if (temp<0):

index=0 #if the measured voltage is negative, set index to 0

else: #otherwise, convert the voltage to a list index

index=int(temp*10)

if (index>7): #limit the maximum index to 7

index=7

batstrip=strip[0:3*(index+1)]+blank[0:3*(8-index)] #assembled string

TINK.setRGBSTRING(0,1,batstrip) #send string data to TINKERplate

time.sleep(.5) #delay and repeat

The above code can be downloaded from github by typing the following instructions on the command line:

git clone https://github.com/pi-plates/TINKERplate-Projects.git
cd TINKERplate-Projects
python3 BATTERYtester II.py

Output

Running the above code will drive the LEDs in the strip to a hight proportional to the battery capacity. The image below shows the ouput of a -mostly- GOOD battery. Note how the top LED is off? A brand new battery would illuminate all eight LEDs.

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