Computer Shopper - UK (2020-10)

ISSUE392|COMPUTER SHOPPER|OCTOBER 2020 91

ififGPIO.iGPIO.inpnput(ut(SESENSONSOR_R_PIPIN):N):

print(print("Moti"Motionon detedetectected"d"))

cameracamera.capt.capture('ure('/home/home/pi/D/pi/Desktoesktop/p/

image%s.jpg'%datetime.datetime.now())image%s.jpg'%datetime.datetime.now())

time.sleep(1)time.sleep(1)

We’ll explain whatthis code does. First, we

need to importthe functions thatweneed,

including the camera, the GPIOcontrol, and

acouple of extrafunctions fortime. Next, we

need to create the camerainsoftware:

camera=PiCamera().

We next set avariable with the GPIOpin

thatwe’reusing to read the motionsensor

(SENSOR_PIN=23). Now we’reontothe

main bit of code.

Here, we’refirst firing up thecamera

preview window with camera.start_preview().

This shows alive feed fromthe camera,

although you can remove this line if

you don’t want to see the file.

Thenexttwo lines cover

configuring the GPIO,

telling the systemwhich

mode we want the pins

to be read in and enabling

our live sensor. We’ve

gone for the Broadcom

number (BCM), where

physical pin 16 is referred

to as GPIO23.

Then, we’reinto our main

loop,which will run until we

hit Ctrl-C.Each time around

the loop we check to see if

motion has been detected

(if GPIO.input(SENSOR_PIN).

If it has, we print amessage

on screen, then we use the

camera.capturefunction to save afile to

the desktop.The line thatwe’ve used uses

the datetime.now() function to append the

date and time to afile, so we can see when

it was captured.

We then sleep forone second to prevent

adeluge of shots. All sample photos are

saved to the desktop.

ADJUSTING SENSITIVITY

If you get too many image captures, you

can tweakthe systemby adjusting the

potentiometers on the side of the motion

sensor.Withthe sensor stood uprightwith

the dome pointing up,the potentiometer

on the leftadjusts the stickiness, the one on

the right sensitivity.

Forthe left, if you turn the dial clockwise,

the sensor continues to reportmovement

after it has been detected, giving you afew

extrashots; all theway anticlockwise gives

you morereal-time movement.

Sensitivity increases how much motion is

required to set offthe sensor,and helps

detect motion at range. Yo ucan gently

adjust both settings, using ascrewdriver,to

get the results you want.

TAKING IT FURTHER

So far so,good, but you can also startto

tweak how the softwareworkstoget it to

do more. First, you can try adjustingthe

systemto save files to somewhereelse on

your computer,oradjust the systemso that

it records video instead, using this code for

video capture:

camera.start_recording('/home/pi/Desktop/camera.start_recording('/home/pi/Desktop/

video.h264')video.h264')

sleep(10)sleep(10)

camera.stop_recording()camera.stop_recording()

Thesystemwe have built

has the components loose so

thatthey need to be

propped up.However, if you

want to build something a

bit better,you can use the

mounting holesonthe

cameraand sensortoplace

themupright.

Thereare plenty of

waterproof housing kits

available, too,soyou can

move your Raspberry Pi

outside and get it to

capturewildlife. Unless

you’ve got awaterproof

power supply nearby,you’ll

need to have abattery pack

to keep your Pi powered.

Yo ucan find plenty of

options online attinyurl.

com/392piprojects1.

ABOVE:Enable thecamera beforeyou canstarttouse it in software

ABOVE:Our script detects motion and captures what’shappening, saving

the files to thedesktop as well as showing alive preview

RIGHT:Youcan adjust the

motion sensitivityusing the

controls on the sideofthe

motion sensor

PI PROJECTS