[TI-H] Re: PIC Interfacing - Web page update(hardware ?)
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[TI-H] Re: PIC Interfacing - Web page update(hardware ?)
Ah I see. Thanks man. I didn't realize that the trisa or trisb had to
be altered to make them input or output. I thought that all I/O pins
were constantly bidirectional. I think your method will probably be far
more efficient. Well done. I have some interesting peripherals in mind
that I can't wait to get started on.
Later,
Cullen Logan
-----Original Message-----
From: ti-hardware-bounce@lists.ticalc.org
[mailto:ti-hardware-bounce@lists.ticalc.org] On Behalf Of Carlos Becker
Sent: Friday, November 23, 2001 6:08 PM
To: ti-hardware@lists.ticalc.org
Subject: [TI-H] Re: PIC Interfacing - Web page update(hardware ?)
At 17:42 23/11/2001 -0600, you wrote:
>OK,
> On your schematic you have each calc serial channel tied to
two
>separate pins on the IC. Is this really necessary? If both channels
>are bidirectional and each pin on the chip is bidirectional then why do
>you need to use two pins per channel. From what I understood the pins
>on the PIC can be input or ouput. If this isn't so then I understand
>the need for it, please correct me if I am wrong. These PICS are very
>particular.
You're right, pins are bidirectional. To change from input to output you
have to change the trisa / trisb registers. It was the first approach I
made, and after trying for about two weeks I thought of changing to two
inputs and two outputs and it worked. So, in conclusion, it didn't work
with only two pins. I tried pullups, pull- downs (if they're called like
that) and everything I could think of. But it didn't work, and curiously
it
did when I changed to two outputs and two inputs.. strange.
The software (pic program & ti-92+ program) were the same in both cases,
so
it's even more strange. (well, the pic code was changed to fit to two or
four pins, just that).
You could try it, it's just question of typing some code. If you make
it,
let me know.
Cya
Carlos Becker
References: