Page 142 - Robots Androids and Animatrons : 12 Incredible Projects You Can Build

high 0
‘Bring RB0 high to light LED
1
‘Wait second
pause 250
4
low 0
1
pause 250 ‘Bring RB0 low to turn off LED
‘Wait second
4
goto start ‘Check switch again
The program for the PICBASIC Pro compiler is as follows:
‘REM PICBASIC Compiler Pro
‘Rem test switch low
input portb.4 ‘Set pin RB4 to read switch
start:
if portb.4 0 then blink ‘If switch is low, then blink LED
goto start ‘If not, check again
blink: ‘Blink LED routine
high 0 ‘Bring RB0 high to light LED
1
pause 250 ‘Wait second
4
low 0 ‘Bring RB0 low to turn off LED
1
pause 250 ‘Wait second
4
goto start ‘Check switch again
The schematic for the read-switch-low circuit is shown in Fig. 6.21.
The switch is connected to an I/O pin labeled RB4. The LED is 121
connected to RB0 through a 470-ohm current-limiting resistor.
Reading switches—logic high
These programs and schematic are the complement to the previous
examples. Look back to Fig. 6.20, example B. The switch labeled B
keeps the I/O pin at a logic low level. When the switch is closed, the
I/O pin is brought to a logic high level.

6.21 Schematic for read-switch-low circuit

Team LRN Intelligence