Using PIC16F88 oscillator as oscillator for other ICs

[Torael_7]

Hi there. I'm an undergrad in the mechanical engineering department at CSU, working on a class project. Amongst the things going into this are a keypad and an LCD. As I can't spare the pins to run either of them directly off the pic, I chose to use an EDE702 LCD controller and an EDE1144 keypad encoder.

However, both of these components require a 4Mhz external oscillator, which I forgot to purchase and now have neither the time to wait for them, nor the money to pay overnight shipping. Fortunately, I've heard that you can run an output off the PIC to serve as a direct TTL clock signal, but I have no idea how to do this and my own research into the matter has not been fruitful. If anyone can offer me any insight, it would be greatly appreciated.

[skimask]

Hi there. I'm an undergrad in the mechanical engineering department at CSU, working on a class project.

{SIGH}

However, both of these components require a 4Mhz external oscillator, which I forgot to purchase and now have neither the time to wait for them, nor the money to pay overnight shipping.

http://www.picbasic.co.uk/forum/show...ing+oscillator
A simple search got that one...try it...you'll like it...

[Torael_7]

{SIGH}

What?

http://www.picbasic.co.uk/forum/show...ing+oscillator
A simple search got that one...try it...you'll like it...

Okay, I'll admit to having not done a search before I posted...sorry. All the answers from that thread look to be driving multiple PIC's off one oscillator crystal, which I lack. Is the basic idea just the same, ie, run OSC2 into OSC1?

[mackrackit]

Okay, I'll admit to having not done a search before I posted...sorry. All the answers from that thread look to be driving multiple PIC's off one oscillator crystal, which I lack. Is the basic idea just the same, ie, run OSC2 into OSC1?

Read the thread skimask pointed to carefully , and yes it is the same idea. Set the osc mode to clockout and it should work. (disclaimer: I have not tried it with your parts )

[skimask]

What?

It's the same story over and over again...and it usually begins with something like "I am a student, 18th year of Engineering 101 and my class project is to build the next best greatest particle accelerator ever designed." Then it goes on with a story, then finally ends up with something I somehow figure would be a simple task for somebody who has been in any Engineering study at all "I need a 5v power supply for X. Has anybody ever built one?"

Okay, I'll admit to having not done a search before I posted...sorry. All the answers from that thread look to be driving multiple PIC's off one oscillator crystal, which I lack. Is the basic idea just the same, ie, run OSC2 into OSC1?

Depending on how it's set up, OSC2 might be OSC1/4, so you get 1Mhz out of 4Mhz. The easiest thing I can think of off the top of my head is to feed all inputs of a 7404 hex inverter (or any logic gate for that matter, use a 2-input Quad AND, or OR, or NOR, or NAND gate chip with the inputs tied together and tie all of the inputs together, whatever works) with a single oscillator, and use the outputs as your clock out. A million different ways to do it....

[mister_e]

We're talking for nothing as we don't know what others chip are... and how they communicate.

If both are 16F88... and the timing is not as this critical, why not using the internal OSC and have 2 spare I/O on each for free.. but we still don't know how timing critical your app is

OK i hear some saying that they used internal OSC and NEVER EVER had any problem even with 115,200 baud ser com...... yeah right

[Acetronics2]

For ALL my PicBasic Forum Helping Friends ...

EDE 702 and 1144 are PICs programmed for special purposes ...


Sooo, using the same clock for them all is described in the relevant AN from µChip ...

so simple as that

Alain

PS : having read the DS 40040B AN could have spared one EDE 1144 ... Serial to Parallell PIC Converter for LCD ( 16F84 ... LOL ! ) could have being found on the Web ... EDE 702 Spared ... ALSO.

[mister_e]

[Acetronics2]

Steeeeeeeve ...

do not mock at ...

http://www.elabinc.com/Semiconductor...7/Default.aspx


just consider 20 US$ ( gogo price ...) a circuit ...

nice job, isn't it ???

Alain

[mister_e]

Scuse moi Alain... mais y faut vraiment avoir la tete dan'l'cul pour acheter ca... non ?

[Acetronics2]

[quote] ... now have neither the time to wait for them ... [/quote)

THE good reason is here ...

But, one must remember electronics teachers in the mechanical sections are ... how to say ??? ... not so good.
Also students are not so ... motivated ... nor !

( I'm talking of what I've experienced ... )

Alain