Explanation:
This code implements four flashing LEDs. This is based on the Microchip PIC Low Pin Count Demo Board.
The example program will blink the four red lights in succession. Press the Push Button Switch, labeled SW1, and the sequence of the lights will reverse. Rotate the potentiometer, labeled RP1, and the light sequence will blink at a different rate.
This implements an interrupt for the switch press, reads the analog port and set the LEDs.
Demonstration program:
#chip 18F14K22, 32
#config MCLRE_OFF
'Works with the low count demo board
'Set the input pin direction
#define SwitchIn1 PORTa.3
Dir SwitchIn1 In
#define LedPort PORTc
DIR PORTC OUT
'Setup the ADC pin direction
Dir PORTA.0 In
dim ADCreading as word
'Setup the input pin direction
#define IntPortA PORTA.1
Dir IntPortA In
'Variable and constants
#define intstate as byte
intstate = 0
#define minwait 1
dim ccount as byte
dim leddir as byte
ccount = 8
leddir = 0
SET PORTC = 15
WAIT 1 S
SET PORTC = 0
'Setup the Interrupt
Set IOCA.3 on
Dir porta.3 in
On Interrupt PORTABCHANGE Call Setir
'Set initial LED direction
setLedDirection
DO FOREVER
INTON
ADCreading = ReadAD10(AN0)
if ADCreading < minwait then ADCreading = minwait
'Set LEDs
Set PortC = ccount
wait ADCreading ms
if leddir = 0 then
rotate ccount left simple
'Restart LED position
if ccount = 16 then
ccount = 128
end if
end if
if leddir = 1 then
rotate ccount Right simple
'Restart LED position
if ccount = 128 then
ccount = 8
end if
end if
'Reset interrupt - this may be been reset so set to zero so interrupt can operate.
intstate = 0
Loop
'Interrupt routine.
sub Setir
if IntPortA = 0 and intstate = 0 then
intstate = 1
wait while SwitchIn1 = 0
setLedDirection
end if
end sub
sub setLedDirection
'Set LED values
select case leddir
case 0
leddir = 1
ccount = 8
case 1
leddir = 0
ccount = 1
end select
End SubSee Also Interrupts, ReadAD10
