12F683 - basic code not working

[Scampy]

Hi Guys,

Playing about with a 12F863 chip for a small project, but to start with thought I would do the basic LEDs flash to ensure programming and that the PIC runs. The code compiled, and ran, flashing the LED on RA0 (on the EasyPIC5 board, which corresponds to GPIO.0). I then added a simple "if then" statement so that if a switch was pressed taking GPIO.1 low the code would jump to the section to flash the LED. But when compiled and loaded to the chip the LED still continues to flash regardless if the switch is pressed or not. I've enabled the pull up on the development board which has no effect

ASM
 __CONFIG _INTRC_OSC_NOCLKOUT & _WDT_ON & _PWRTE_ON & _MCLRE_OFF 
endasm

TRISIO = %11111110
ANSEL = 0   		
GPIO.0 = 0
CMCON0=7

Motor var GPIO.0
Switch1 var GPIO.1
Switch2 var GPIO.2

main:
If Switch1 = 0 then 
goto demo
else 
goto main

demo:
high Motor
pause 1000
low Motor
pause 1000
goto main
endif
Goto main

Any ideas why ?

[Scampy]

Interestingly this works

ASM
 __CONFIG _INTRC_OSC_NOCLKOUT & _WDT_ON & _PWRTE_ON & _MCLRE_OFF 
endasm

TRISIO = %11111110
ANSEL = 0   		
GPIO.0 = 0
CMCON0=7

Motor var GPIO.0
Switch1 var GPIO.1
Switch2 var GPIO.2

main:
If Switch1 = 1 then 
gosub demo
endif 
goto main

demo:
high Motor
pause 1000
low Motor
pause 1000
goto main
REturn

[Acetronics2]

Hi, Malc

I would have written ...

ASM
 __CONFIG _INTRC_OSC_NOCLKOUT & _WDT_ON & _PWRTE_ON & _MCLRE_OFF 
endasm

TRISIO = %00111110
ANSEL = 0           
GPIO.0 = 0
CMCON0=7

Motor var GPIO.0
Switch1 var GPIO.1
Switch2 var GPIO.2

main:

If !Switch1 then 

demo:
  high Motor
  pause 1000
  low Motor
  pause 1000
endif

goto main

but it's just me ...

at least, your "endif" should be placed just before the " demo " label ...

cause the " IF " condition never sees the " ENDIF " condition reset ....

tadaaaaaa ...

Alain

[AvionicsMaster1]

I'm assuming your using PBP3 and to do configs you need to do them like this and both "config" lines need to be in caps. I know PBP2.6 was different but with either version both "config" lines need to be in caps.

#CONFIG
;configuration directives in Assembly Language
#ENDCONFIG

TRISIO on the 12F683 is only 6 bits wide so I'm wondering if you need to change it to TRISIO = %111110. I think when you set the TRISIO and the GPIO as input and low respectively you'll always have a low at GPIO.0. When you set the pin low and told it to wait for a low it did what you told it to do. That is go to the demo subroutine. Since you changed it to =1 you had a state change and the chip could sense that. The reply by Acetronics2 did that by using the ! sign.

Your second take on the subroutine and endif look better.

As usual I'll await for someone to tell I'm wrong.

[Scampy]

I'm assuming your using PBP3 .

Sorry, wrong assumption - using 2.60

Quick question and slightly off topic, but related to this project... I'm using an H-bridge to control the motor as I need it to be bi-directional. I've been experimenting with some NPN and PNP transistors that I had in my hobby box, BC639 and BC640 and have had a small low current motor running from the PIC. However the actual motor I will be using is a 540 type with a 6:1 gearing. Even though it will be running from a 3v supply (separate to the 5v pic supply) my guess is that the current might be too high for the BC639 / 640 transistors. Can anyone advise if using these transistors would be OK for such a motor, or should I use something like the TIP220 transistors ??

[wdmagic]

I would use FET's, or a L298 chip. the 298 works great. the FET's i use are a bit overkill for what your doing but you can get lower values.
some that work well for all hobby motors from the old style that were in tape decks to modern RC racecars is
RFP12N10L
IRF540
IRF9530

[Scampy]

Following suggestions I've ordered a module from e-bay based on an L298N controller, which should work as under testing the 540 motor was drawing 0.7A and these things are rated at 2A.

I'm now working on the light detection side of the circuit. Basically the idea is to automatically open a door at dawn (wife now keeps chickens !). So when the light level reaches or exceeds a threshold, the motor runs, opening the door until the door hits a micro switch which then changes a pin status which then turns off the motor.

I've purchased a 16k-33K LDR from Maplin ( http://www.maplin.co.uk/p/16k-33k-oh...resistor-n57ay ) and connected that from the 5v line to GPIO.0 and covering the LDR makes the associated LED on my development board go out, and increase in brightness due to ambient light or when a bright torch is shon on the LDR. So the resistance is varying based on the light level, so far so good. Now the issue I'm having is that having set the ACD to 8 bits this should give me a 0 - 254 range of values... but in testing to get the motor to run at various values, these are not what I would expect.

Here's the test code:

ASM
 __CONFIG _INTRC_OSC_NOCLKOUT & _WDT_ON & _PWRTE_ON & _MCLRE_OFF 
endasm

' Hardware configuration
' ======================



TRISIO = %001111 
ADCON0 = %10000001 
ANSEL = %00110011 
DEFINE ADC_BITS 8
DEFINE ADC_SAMPLEUS 50 
CMCON0=7

Motor1 var GPIO.4
Motor2 var GPIO.5
ADChannel0 var word

GPIO = 0 ' clear all output
Pause 50 ' internal oscillator settle time

main:
low Motor1
low Motor2
adcin 0,adchannel0 ' Read AN0

If adchannel0 >2 then
  high Motor1
  Low Motor2
  pause 5000
low Motor1
low Motor2
endif

goto main

If I put in <1 for the argument, the motor runs even with the LDR covered. If I put in >1 the motor won't run unless I shine the torch directly on the LDR. I'm sitting here in ambient light with the sun shining in the window so the motor should be running.

Any ideas as to what I'm doing wrong ?

[Demon]

Do you use a word for 8 bit as well?

Motor2 is never going on by the way.

Robert

[Scampy]

OK corrected that (original example code must of been for higher resolution...) but still no joy in setting the thresholds

Motor two is always off in this example as its the other terminal to the H bridge

[aratti]

You should post the schematic of your project in order to get proper help. Very likely your problem is in the hardware arrangement.

Cheers

Al.