This circuit will take a light reading then display a number between zero and 99.
Step 1: Parts you will need
Major Components in Project
To make the 0-99 LED display you will need…
~ photo resister
~ Arduino
~ 9 different wires
~ 2 seven segment led displays
~ bread board
~ staples
~ fine grit sandpaper
~ and a stapler
Step 2: The Code
This is the code for the Arduino
I tried to explain it the best I could in the comments but I ran out of room in some of them
so lines of interest
int pinstringA[11] {
HIGH,LOW,HIGH,HIGH,LOW,HIGH,HIGH,HIGH,HIGH,HIGH};
these strings code for the state of one segment each so
pinstringA[0] == HIGH this means that when the number is zero segment A is High
light = map(light, 0, 1024, 100, 0);
the pullup resister flips the values of the photo resister so a lot of light makes the number low
so I Changed the scale from 0 to 1024 to 0 to 100 then flipped it.
tens = light / 10;
This finds the tens value eg. 19/10= 1 remainder 9 the remainder is then thrown out
the line below saves the remainder for the ones place
PORTD = PORTD & B00000011;
This turns all the pins on port d off but leaves pin 0 and 1 alone (for serial communication)
see http://arduino.cc/en/Reference/PortManipulation for more details
Step 3: STAPLES!!?!
With the code downloaded you need to connect the board
you need to connect the corresponding pins together so pin one
of one display connects to pin one of the other display
Staples works very well for this they are six pins in length the only
bad part is that the glue that holds them together is non conductive so
take the sandpaper and rub off the glue on the downward leads
next pop them in a stapler and use it to push the actual staples apart
push them into the bread board leaving room for the display and wires
to connect to Arduino.
Step 4: Attach wires
Attach wires to the led.
Step 5: Connect to Arduino
Connect each wire to the Arduino.
Segment A to pin 4
B to 7
C to 8
D to 6
E to 3
F to 2
and G to pin 5
Also connect ground from ones place to pin 9
and ground from tens place to pin 10
Last connect the photo resister to the Arduino ground and Analog 0
For more detail: Make A 0 to 99 Light display Using Arduino
