I thought I had a basic understanding of AD but not too sure now. My 16f887 is configured with RA0 on a pot and an LED on PortD,0 So I wrote an exercise with GCGB using the ReadAD example under Help except I used 2 IF statements in a loop to turn the LED on or off depending on the pot. It works fine and the LED turns on and off as I manipulate the pot.
So for the heck of it I changed the I/O line to "DIR PORTA,1 In" and "ReadAD(AN1)" (instead of the "0" pin) and execution does not changes and there are no compile errors. I then changed to PORTA, 5 and ReadAD(AN5) and again no change. Nothing is hooked to the 2nd or other pins of PORTA. Am I missing something? Thanks for such basic help.
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Again, this works as designed reading AN0, the pin the pot is tied to. The mystery to me is why the pot directs the LEDs to be on or off when I am reading a different pin??
Thanks George
;Chip Settings
#chip 16F887,8
'Chip Settings
'A program to flash two LEDs on PORTD, bits 0 and 1
'Set the pin directions
Dir PORTA.1 In
Dir PORTD.0 Out
Dir PORTD.1 Out
var = ReadAD(AN1)
'Main routine
Start:
'Turn one LED on, the other off
If ReadAD(AN1) > 120 then
Set PORTD.0 On
Set PortD.1 Off
end if
If ReadAD(AN1) < 120 and ReadAD(AN1) > 80 then
Set PORTD.0 Off
Set PORTD.1 On
End if
Wait 10 ms
GOTO Start
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Thanks, here's the code: Again, this works as designed reading AN0, the pin the pot is tied to. The mystery to me is why the pot directs the LEDs to be on or off when I am reading a different pin?? Thanks George ;
;Chip Settings
#chip 16F887,8 'Chip Settings
'A program to flash two LEDs on PORTD, bits 0 and 1
'Set the pin directions
Dir PORTA.1 In
Dir PORTD.0 Out
Dir PORTD.1 Out
var = ReadAD(AN1)
'Main routine
Start:
'Turn one LED on, the other off
If ReadAD(AN1) > 120 then
Set PORTD.0 On
Set PORTD.1 Off
end if
If ReadAD(AN1) < 120 and ReadAD(AN1) > 80 then
Set PORTD.0 Off
Set PORTD.1 On
End if
Wait 10 ms
GOTO Start
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If AN1 is just floating and not connected to anything then a charge could build up on the pins stray capacitance causing the A-D converter to measure a voltage and turn on the leds. Maybe there is just enough leakage between the pot pin and AN1 for the voltage on AN1 to follow the pot voltage. You could try connecting AN1 to ground if it is floating and see whether it stops.
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I have not compiled the example. I usually assign a variable to an analog reading, then perform conditional statements/maths on the variable. A learned habit, or conditioned by limits of the compiler in "certain situations"? For instance, this code worked fine for an '887.
Iout = ReadAD10(AN1) ;Vcurrent Maxim4081 or Allegro Hall Effect
Iout = (Iout-512)*488/20
Kent
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Replies 6 and 7. Excellent. Yes putting AN1 to ground when reading AN0 fixed the problem. Amazing experience. And yes, for such learning I permitted myself to be a sloppy programmer…calling functions repeatedly instead of assigning variables. I'm new at COW and I'm cautious about variables because I haven't seen type declarations, etc. anywhere. Maybe there are none.n Thanks for all the help. That mystery held me up a lot for such a simple test.
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I thought I had a basic understanding of AD but not too sure now. My 16f887 is configured with RA0 on a pot and an LED on PortD,0 So I wrote an exercise with GCGB using the ReadAD example under Help except I used 2 IF statements in a loop to turn the LED on or off depending on the pot. It works fine and the LED turns on and off as I manipulate the pot.
So for the heck of it I changed the I/O line to "DIR PORTA,1 In" and "ReadAD(AN1)" (instead of the "0" pin) and execution does not changes and there are no compile errors. I then changed to PORTA, 5 and ReadAD(AN5) and again no change. Nothing is hooked to the 2nd or other pins of PORTA. Am I missing something? Thanks for such basic help.
Please copy and paste your code here.
jooe
Check the document for 887
they tricked you!
RA5 is actually AN4
and RE0 is AN5
and RE1 is AN6
Thanks, here's the code:
Again, this works as designed reading AN0, the pin the pot is tied to. The mystery to me is why the pot directs the LEDs to be on or off when I am reading a different pin??
Thanks George
;Chip Settings
#chip 16F887,8
'Chip Settings
'A program to flash two LEDs on PORTD, bits 0 and 1
'Set the pin directions
Dir PORTA.1 In
Dir PORTD.0 Out
Dir PORTD.1 Out
var = ReadAD(AN1)
'Main routine
Start:
'Turn one LED on, the other off
If ReadAD(AN1) > 120 then
Set PORTD.0 On
Set PortD.1 Off
end if
If ReadAD(AN1) < 120 and ReadAD(AN1) > 80 then
Set PORTD.0 Off
Set PORTD.1 On
End if
Wait 10 ms
GOTO Start
Ooops - forgot to logon:
Thanks, here's the code: Again, this works as designed reading AN0, the pin the pot is tied to. The mystery to me is why the pot directs the LEDs to be on or off when I am reading a different pin?? Thanks George ;
;Chip Settings
#chip 16F887,8 'Chip Settings
'A program to flash two LEDs on PORTD, bits 0 and 1
'Set the pin directions
Dir PORTA.1 In
Dir PORTD.0 Out
Dir PORTD.1 Out
var = ReadAD(AN1)
'Main routine
Start:
'Turn one LED on, the other off
If ReadAD(AN1) > 120 then
Set PORTD.0 On
Set PORTD.1 Off
end if
If ReadAD(AN1) < 120 and ReadAD(AN1) > 80 then
Set PORTD.0 Off
Set PORTD.1 On
End if
Wait 10 ms
GOTO Start
If AN1 is just floating and not connected to anything then a charge could build up on the pins stray capacitance causing the A-D converter to measure a voltage and turn on the leds. Maybe there is just enough leakage between the pot pin and AN1 for the voltage on AN1 to follow the pot voltage. You could try connecting AN1 to ground if it is floating and see whether it stops.
I have not compiled the example. I usually assign a variable to an analog reading, then perform conditional statements/maths on the variable. A learned habit, or conditioned by limits of the compiler in "certain situations"? For instance, this code worked fine for an '887.
Iout = ReadAD10(AN1) ;Vcurrent Maxim4081 or Allegro Hall Effect Iout = (Iout-512)*488/20Kent
Replies 6 and 7. Excellent. Yes putting AN1 to ground when reading AN0 fixed the problem. Amazing experience. And yes, for such learning I permitted myself to be a sloppy programmer…calling functions repeatedly instead of assigning variables. I'm new at COW and I'm cautious about variables because I haven't seen type declarations, etc. anywhere. Maybe there are none.n Thanks for all the help. That mystery held me up a lot for such a simple test.