Driving LED's With Digital I/O Lines
LED's may be driven by digital I/O lines and require only a current
limit resistor to limit current to 20mA or less. Digital I/O lines can source ( LED 1) or
sink ( LED2) LED current. If the I/O line is to sink LED current, the
"RESPAn" command is used to turn the LED on and the "SETPAn" command
is used to turn the LED off.. If the I/O line is to source LED current, the
"SETPAn" command is used to turn the LED on and the "RESPAn" command
is used to turn the LED off. The following example shows the use of an ADR101 to
control two LED's in each of the before mentioned configurations.
10 OPEN "COM1:9600,N,8,1,CS,DS,RS" AS#1
20 PRINT#1, "CPA11111100"
30 REM TURN ON LED#1
40 PRINT#1, "SETPA0"
50 REM TURN OFF LED#1
60 PRINT#1, "RESPA0"
70 REM TURN OFF LED#2
80 PRINT#1, "SETPA1"
90 REM TURN ON LED#2
100 PRINT#1, "RESPA1"
110 BEEP
120 GOTO 30
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