Nigel's PIC Tutorial - Main 1 Revisited

[Inquisitive]

Thank you for your consideration.

Looking for somebody to look over my shoulder on my first board etching project. Yes, the original was done on Veroboard. I would like to have mine etched. This gives me the opportunity to use my newly learned Kicad skills.

The original schematic is like this:

My version is slightly modified. Here is where I need somebody to double check me.

Here is my PICkit 2 ICSP Datasheet Circuit Diagram.

If you see any errors or short comings in my design please inform me. Your opinions are appreciated. Thank you for your time.

 

[Nigel Goodwin]

At a quick glance it looks fine, my only query would be the reset components - as one of the reasons for using the 16F628 was it's internal reset (allowing MCLR to be used as an input pin) they aren't required.

Assuming you want to add them for compatibility with more devices?, then I would suggest adding the option for an external crystal and capacitors on RA6/7 - but, along with the reset components, you're limiting it's capabilities for the tutorials.

 

[Inquisitive]

Hi Nigel,

Not sure I'm clear on the first paragraph. Are you saying I don't need the 1N4148 circuit on the MCLR?

As for adding a crystal what mode would you recommend. LP, XT or HS and frequency?

 

[Nigel Goodwin]

Hi Nigel,

Not sure I'm clear on the first paragraph. Are you saying I don't need the 1N4148 circuit on the MCLR?

No, the resistor and capacitor for the reset circuit aren't needed, although the diode is more commonly replaced by a simple resistor now - at least on the later devices.

As for adding a crystal what mode would you recommend. LP, XT or HS and frequency?

It's really up to you

The internal oscillator is 4MHz, if you wanted to add a an external one you could make it a 4MHz (for greater accuracy), or a 20MHz for greater speed.

 

[Inquisitive]

Might add a 20 MHz option.

Assuming you want to add them for compatibility with more devices?, then I would suggest adding the option for an external crystal and capacitors on RA6/7 - but, along with the reset components, you're limiting it's capabilities for the tutorials.

Was only planning on the PIC16F628A as the only PIC for this version. With my version will I hinder the ability to do the tutorial circuits?

 

[Nigel Goodwin]

Might add a 20 MHz option.



Was only planning on the PIC16F628A as the only PIC for this version. With my version will I hinder the ability to do the tutorial circuits?

Just leave the resistor and capacitor (R1 & C4 - and D2 for that matter) on MCLR out of the board - they aren't going to be used, and 'may' interfere with the correct action of RA5. Add a 10K from the MCLR pin to +5V for the ISCP.

 

[Inquisitive]

Looks like TFMS5360 might be hard to get here this side of the pond. Any suggestions for a cross reference component?

 

[jpanhalt]

A quick look at its datasheet suggests that the Vishay receivers (e.g., TSOP 38xxx) may be good substitutes. The "38" denotes 38 kHz for the tuned frequency. Other frequencies are available.

John

 

[Mike - K8LH]

Here's a relatively inexpensive option for an IR Receiver IC and an IR Remote;

 

[Inquisitive]

Good idea Mike, Thanks.

 

[Nigel Goodwin]

Looks like TFMS5360 might be hard to get here this side of the pond. Any suggestions for a cross reference component?

Just take one out of a scrap item, the actual model (or indeed frequency) makes very little difference.

 

[Inquisitive]

Finalized my design choice. Consulted with an friend on some power section modifications and took his advice. See below.

Since for me this was also an exercise in learning and using Kicad. Why kicad? Because it did not restrain me to a small board size. The final schematic gerbers where sent off to Oshpark for manufacture.

Here is the completed board.

Its Alive!!!

Thanks Nigel and Ian.

Now for some tutorial work.

 

[Mike - K8LH]

That looks really nice... Bravo...

 

[Inquisitive]

That looks really nice... Bravo...

Thanks Mike

 

[large_ghostman]

Very posh!! whats wrong with dead bugging

 

[Nigel Goodwin]

Nice board

I would only comment on the capacitor values round the regulator - there's little point fitting a 10uF and a 1uF, the values are far too close. Either on it's own would be perfectly fine, but if you want to use two, use a 10uF and a 0.1uF or 0.01uF.

 

[large_ghostman]

Great board but I would worry the switch would put strain on the board eventually. But WTF do I know

 

[Nigel Goodwin]

Great board but I would worry the switch would put strain on the board eventually. But WTF do I know

Those switches are nice light action ones.

 

[Inquisitive]

Nice board

I would only comment on the capacitor values round the regulator - there's little point fitting a 10uF and a 1uF, the values are far too close. Either on it's own would be perfectly fine, but if you want to use two, use a 10uF and a 0.1uF or 0.01uF.

My bad. There is an error in the drawing. I actually used 0.1uF instead of 1uF, by the way. Thanks for pointing that out.

 

[Mikebits]

Your PCB looks nice, I am gonna have to give that KiCad a try...