Loop Problem please help

[keithdoxey]

I would say there is some form of hardware fault.

From your code, I dont see how the relay could buzz as you only have code to turn it on if Adval is between 500 and 600. There is nothing in the code that I can se that will turn it OFF eg PortB.6 = 0.

The buzzing could be due to the PIC resetting. Connect an LED to an unused pin and light it for 1 second then turn it off in the initialisation code. If you see the LED flashing or aapparently staying on then for some reason your PIC is resetting.

From the code you have posted, the first time ADVAL is 500-600 the relay will operate and then stay that way forever.

I notice that you update the LCD inside the loop and that LCD Enable is on B5.
This pin will be going high and low as the LCD is updated.
Do you have a short between B5 and B6 ?

[wildbilly]

Thanks to all who responded. I have dug deeper and found that replacing the 16F88 with 16F84 or 16F628 works just fine. Not the ADC portion, just turning PORTB.6 on. With the 16F88 the LED would pulse. What is strange is that selecting the 16F88 in the device selection menu in MicroCode Studio Plus and then compile would give strange errors. To fix the errors I had to change the directory. I stripped the code to bare minimum because the issue was with holding the port pin on solid. As you can see, the code is very simple. With code below, the 84 and the 628 works as expected. I know the 88 is fine as I tried three. The problem could be with MicroCode Studio.

loop:Lcdout $fe, 1 'Clear screen
Lcdout "Testing 16F88"
Pause 100 'Wait

HIGH PORTB.6

Goto loop ' Do it forever

END

[keithdoxey]

ANSEL = %00000000 ' Disable Analogue Inputs

I had the same problem the first time I used a 16F88

Oops, just realise that you NEED analogue inputs but disable the ones that are on the Port B pins that you are using

Use ANSEL=%00000001 ' Enable AN0 only

By default the analgue inputs are enabled. To update your LCD display the PortB data register is read, modified and written back to. Because B6 (your relay pin) by default is AN5, this is read as a ZERO rather than the ONE you set it to in your code. This means that when you initially set it it works OK but as soon as the LCD is updated again it gets rewritten as ZERO.

HTH

[wildbilly]

Thank you. I will try that ansel in a few minutes and get back to post the results. Thank you very much on your observation about the LCD. I noticed you mentioned that before. I have always wondered why in all the examples I have seen in the DEFINES, the ports were not all the same. I could not find any explanation as to why that was. Thank you for being persistent in pointing that out and offering the explanation.