Feb
22

Analog / Digital Input, Output

This is an example of using 2 variable resistors as analog inputs and a switch as a digital input to control 8 LEDs with a PIC18F452 chip. Variable resistor 1 is used to control which LEDs light up. The second variable resistor controls how fast the LEDs blink. The switch decides whether the LEDs blink or not. MAX232CPE is used to allow serial communication with a computer. PICBASIC was used to program the chip. This is how the board was set up:

The following is the code:

DEFINE LOADER_USED 1
DEFINE OSC 20
INCLUDE “modedefs.bas”

DEFINE ADC_BITS 10
DEFINE ADC_CLOCK 3
DEFINE ADC_SAMPLEUS 20

ADCON1 = %10000010

TRISA = %11111111
TRISB = %00000000
TRISC = %10001000

adc VAR WORD
adcbyte VAR BYTE

SPEED VAR WORD
SPEEDbyte VAR BYTE

SWITCH VAR PORTC.4

main:

IF SWITCH = 1 THEN

ADCIN 0, adc
adcbyte = adc/140

ADCIN 1, SPEED
SPEEDbyte = SPEED/140

PORTB = %00000001 << adcbyte
PAUSE 100*SPEEDbyte
PORTB = 0
PAUSE 100*SPEEDbyte

ELSE
ADCIN 0, adc
adcbyte = adc/140

PORTB = %00000001 << adcbyte

ENDIF

GOTO main

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2 responses for this post

  1. Giulio Castorina Says: 24.02.10 at 4:48 am

    Hi there,
    very interesting…looking forward to see more!
    Have you some good book suggestions about physical computing devices?

    Cheers,

    Giulio

  2. crtl-i Says: 24.02.10 at 6:26 am

    There’s a book called “Physical Computing,” which I sometimes look at. Most of the useful information is on the web I think.

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