connect two pics

[soki]

Hi to the forum!

I already searched the forum about how to connect two pics, i found that many ppl suggesting using serin2 and serout2 commands.

Iam builiding a robot for avoiding obstacles. One PIC16f877a is used for collecting data(actually the voltage is changing) with a/d channels from a sharp IR sensor and display them on a lcd, I want when the sensor gets a minimal voltage value (indicating the robot is close to an obstacle) then the second PIC 16f84 become active (with a l293d chip) to make the dc motors moves the way I want.

Is there a simpler way to just make the second PIC enable for some minutes to just run the program with the dc motors, and then become inactive again without serial communication?

I know the simplier solution is to put everything on PIC 16f877a but for some strange reason the big PICs dont work well with l293d and dc motors only the smaller ones like pic16f84 or pic16f628 do thats why i need 2 pics.

Any help will be very much appreciated.

Thank you very much.

[mackrackit]

SERIN or SERIN2 is about as simple as it gets.

Why do you not want to use it?

[Jumper]

Hi,

You might want to find out why the big PIC doesnt want to work properly. Do you have a nice and clean supply voltage (or do you get spikes when you start and stop the DC motors)?

Do you have enough power at all?

Do you have capacitors close the the power pins of the pic?

Do you have brown out enabled?

PCB or a ball of soldered wires?

X-tal, RC or external oscillator?

I would reccomend you to try to solve this issue and then you would get a much easier project. There must be a reason for this so I think we keep the 2 pic design as Plan Z.


What do you mean with "it doen't work well"?
/me

[soki]

Thank you for your replies.

When I say it doesnt work well I mean when I make a program for big PICs and I want for example rotate one dc motor right then pause 2 sec then rotate left pause 3 sec etc, it just dont work or work wrong, for example it will rotate only right and then stop working at all or if its a big loop it maybe stop in the middle of the program.With small pics it works like champion.


Are there some examples with serial communication? I tried to find the "sixpics" project someone mention but there isn't in melabs program examples.

Thank you very much.

[skimask]

When I say it doesnt work well I mean when I make a program for big PICs and I want for example rotate one dc motor right then pause 2 sec then rotate left pause 3 sec etc, it just dont work or work wrong, for example it will rotate only right and then stop working at all or if its a big loop it maybe stop in the middle of the program.With small pics it works like champion.

Quite frankly, to me, that just doesn't make any sense. But, I'll bet, I'd just bet, if, and only if, you posted the code that you used in both PICs, the one that worked and the one that failed, you might, just might, get a quick answer as to why one works and the other one seems to fail.
But that would be just too easy...

Are there some examples with serial communication? I tried to find the "sixpics" project someone mention but there isn't in melabs program examples.

Ya know what works for me?
Typing 'Serial Communication between 2 PICs' in the Search box.
Crazy how that works ain't it?

[mackrackit]

I agree with Jumper, find the problem.
Maybe post the problem code??

SERIAL-- really simple example . Much more to add, but the basic idea.
SEND

SEROUT2, PORTX.X, MODE,[DEC 9]

RECEIVE

SERIN2, PORTX.X, MODE,[DEC VAR]
IF VAR = 9 THEN LABELX

[Jumper]

If you have connected anything on PORTA and you dont get the results you want.... this one I leave for Melanie to answer if needed :-)

Show us your HW setup and some code, it should not be rocket science to rotate a DC motor with the 877A.

So dont give into Plan Z just yet.

/me

[soki]

The program I put in both small and big pics are the same,not different programs! On small pics it work on big not well!