Disabling Analog Port on PIC16f88

[PINTO]

Hi Benj.

Compliments of the season.
I'm trying to get a small project going were i'm inputing 2 frquencies to pin A0 & A1 and internenally comparing to an internal counter and when the inputs reach a preset value ( 110 & 160Hz) than RB7 & RB8 will go ON respectively, if the frequency fall or goes above the preset value the output will go OFF.
The program works well when I simulate it in PROTEUS but not on the actual CHIP. I have other LED's on Portb that work but what's connected to Porta doesn't work.
I think the problem is I have to configure Porta as a digital I/O and as far I can see from the data sheet Port a4 to a0 are configured as Analog as default after reset.
Could you help me configuring Porta as an Digital I/O.

Many Thanks.

Pinto Ramos

By the way, when will FlowCode 4 be availabe, I would like to place an order.

[Benj]

Hello Pinto

Flowcode should set the porta pins to digital by default at the start of your program. Look at the compiled C code and you should see the following line at the start of your main function:

ansel = 0x00;

Which pins of porta are you using? RA5 / MCLR pin is capable of input only incase this is the problem.

Best way to test is to write a simple program to output bits or input bits on porta to ensure what you think is going to work is actually going to work.

Flowcode 4 should be available March time, sorry for the extra delay but were currently still cramming in functionality.

[PINTO]

Hi Benj,

Thanks.
I checked the C code generated and noticed that the compiler generates the following code:

Code: Select all

void main()
{
	
	//Initialisation
	ansel = 0;
	cmcon = 0x07;

ansel=0 and not ansel=0x00 as you mentioned.

Could that cause a problem?

Regards


Pinto

[Benj]

Hello Pinto

Unfortunaltly ansel = 0 and ansel=0x00 equate to the the same thing -> portA = digital.

Can you output values to the port?

[PINTO]

Hi Benj,

I checked and FlowCode generates

Code: Select all

void main()
{
   
   //Initialisation
   ansel = 0;
   cmcon = 0x07;

but I cann't get the F88 to see the frequency on the RA0 & RA1.
I tried the same code with F877 and connected two LCD dislays to port C & D and inserted flags on the code to see if the code actually branched and the code works with the 877.
I than decided to try a 628 and voilΓ , it worked.
I have no idea of what the problem is with the F88.
It doesn't matter what chip I use for the my application, but is frustating not to been able to get the f88 to work. Anyway I will have another go later again.

Thank you for your help.

I can't wait for my book to arrive, Ive ordered a week ago and should be here any time and more importante the release of Flowcode 4.


Regards


Pinto