Looking for a fresh set of eye's

[aurbo]

Greetings

I've been tossing around this project for many weeks now..

I'm looking at a 7 digit Julien calendar clock in large led format.

D100, D10, D1, :, H10, H1, :, M10, M1 "365:23:59" 365 days, 23 hours, 59 min

The ":"'s are pulsing to the seconds.

I would like to use led's to make up the individual segments, which require a higher power and a higher pin driver mA. The clock needs to be seen from a moderate distance so scaling led segments would be the cheapest solution.

I've used the 18F4525 only because I have one handy.. it doesnt stop me from changing it out should I find a beter suited PIC. Or if someone has already created a code based on another PIC.

Could someone take a quick look at the attached file. and let me know if I'm on the right track with this.. any suggestions to reduce the chip count or optimize the circuit would be greatly appreciated.

Regards
Steve

[mackrackit]

Maybe I am missing something, but why the second chip? The 18 has plenty of pins.
With 12 volt on the LEDs you may want to think about some sort of isolation just in case something goes wrong the PIC will not be over amped or over volted? (mosfet, opto, transistor)
Other than that it looks like it should work.

[aurbo]

Thanks for the input

I think something is missing as well.. I just cant place my finger on it.

The 595 keeps the Vf of 12Vdc needed to drive the led's away from the PIC, grounding the cathodes also keep the amps away.

I was thinking of using a SINGLE 595 to drive all the segments from pic port C and drive the cathode from port D but I'm not sure how to isolate the 12Vdc using that layout.

Not sure if I'd need a 2803 or another 595 to protect the cathode end of things, but if I did, I'm not sure of how that would lay out in the schem.

Cheers

Steve

[mackrackit]

OOPPS, I was seeing another PIC and not a shift reg.

[aurbo]

All on the breadboard, ready to go

Changed the dp circuit to reflect the other seg's.

Looking at the layout. I can now use the Pic of my choice.

Just dont know which to use.

I guess it depends on whether I can find a quick test code or an actual clock code to run on this.

Anyone have a 3 wire clock code to try using one of the following Pic's?

16F627A
16F628
16C54
18F4620
18F4525

Cheers
Steve

[aurbo]

Here is the latest schem for my project.

I'm lost and bewildered on the coding part.
Hex, ASM, C, Basic, Etc.. I have no clue where to start.

The Schem is based on a 3 wire SPI setup, You can use almost any Pic that will handle this.

Would anyone have a test code sample, Using a 16F627A that will interface with the 595's and light up a single segment in order from a-g and dp of each digit and then move on to the next digit. ( I have several 16F627A's I can toast learning this code on)

I think Basic would be the easiest for me to understand. I understand what it does, why it does it, but not HOW..

Any help at this point would be greatly appreciated and possibly save my sanity. So far from just an idea to a circuit has taken just over 2 months, I'm in no rush to just make this thing and move on.. this is my learning "Pic" project.

Just need a boost on this.

Cheers
Steve

[skimask]

I'm lost and bewildered on the coding part.
Hex, ASM, C, Basic, Etc.. I have no clue where to start.
The Schem is based on a 3 wire SPI setup, You can use almost any Pic that will handle this.
Would anyone have a test code sample, Using a 16F627A that will interface with the 595's and light up a single segment in order from a-g and dp of each digit and then move on to the next digit. ( I have several 16F627A's I can toast learning this code on)
I think Basic would be the easiest for me to understand. I understand what it does, why it does it, but not HOW..
Any help at this point would be greatly appreciated and possibly save my sanity. So far from just an idea to a circuit has taken just over 2 months, I'm in no rush to just make this thing and move on.. this is my learning "Pic" project.


Just for some idea on how complex a project like this can actually be:
http://www.picbasic.co.uk/forum/showthread.php?t=6033

And I think you'd be much better off working your way up to it.
Have you made 'blinky' yet? (that's what we commonly call the PIC controlled blinking LED)

We (we being those that have been at it for awhile) have all said it before, and will probably say it again, if you don't start small and work up to whatever it is you're hoping to accomplish in the end, you'll give up and have X dollars of hardware that'll never get used again because you're sick of failing.

[mister_e]

The RX part will never work, there's a missing Pull-up in there.

Easier to use a ULN chip and skip the Shift register for a single display. For more than 1, still possible to use I2C I/O extender, or even some dedicated led drivers from Maxims.

I doubt that everything would fit in a 16C54 or 16F627. Maybe possible with a 16F628.

How many different 7 segments display you plan yo use?