Help designing a PIC16F877 Circuit, Btw, I'm new he

[fanir]

pic16f877 circuit

I've been searching around for good forums and finally stumbled here. As you can see, I'm new here so if there's much flaming/battering/slapping/kicking, please do. biggrin.gif

Okay, back to business. I'm currently designing a digital circuit with a PIC and a MAX232 IC. Here's some pictures. Oh Btw, the idea here was never mine.

**broken link removed**

Here's the PCB and supposedly how it's gonna look.

**broken link removed**
**broken link removed**

Sooooo, my question is, I have almost all the components there but I couldn't find one for a 20Mhz Crystal so I tried a 33-470kt. Equivalent?

Oh and can I try a 10k pot for a 10k linear pot? BYV26E[928] Shottky for BAT85?

I'm doing it on a stripboard/veraboard and not on a PCB [my country doesn't allow etching], I've seen from sites that they used a enamelled copper wire for the connections, should I use this?

Thanks in advance thumbsup.gif Hope to hear those nifty replies soon lol.

 

[IanP]

connect db9 to stripboard

If you can't find 20MHz crystal you can use any other crystal you have or can get, but, you will need to modify values in some registers to correct timing of UART..

Any potentiometer or diode can be replaced with what you have .. after all they are not critical in this circuit ..

For wiring of veroboards the best wire is Tefzel Insulating Wrapping Wire: **broken link removed**
It is AWG30 insulated, solid and tinted wire ideal for any wiring job ..

Regards,
IanP

 

[fanir]

pic16f877 ic singapore

Hello there. Thanks mate for the quick reply. Anyway, can I use any other wire like copper or something other than the above? I making this a plan B in case I can't find it [I'm from Singapore Btw].

I went around and searched and found this - **broken link removed**
Is this wire good enough?
I'm not looking for the best out there, just one that works/decent lol.

One more thing, a little curious as in why is diode/pot not critical in the circuit. Just curious lol. . What about resistors?

Thanks again.

 

[IanP]

creating footprint pic16f877

With wiring veroboards you want to be sure that all connections are correct and that there is no short-circuit(s) problem ..
Enamalled wire is also good, but you need to be much more careful while using it ..
I am pretty sure in Singapore you can get insulated wire, which by all means is my preferred option ..

Critical components in a circuit determine condition(s) under which a circuit works ..
For example, if you use as pull-up resitors in digital applications (in most cases non critical components) 4.7kΩ, 10kΩ, or 2.2kΩ in 99.9999% circuits will work ..
From this perspective, if this potentiometer is 4.7kΩ or 10kΩ, linear or logarithic, it really doesn't matter, and it doesn't change the fact that this circuit will work; sometimes, however, logarithmic pot will be just more convinient for you (than a linear one) to adjust something ..

Regards,
IanP

 

[fanir]

pic16f877 wiring circuit

Cheers mate, that's all I needed to know. Cheers.

Added after 1 hours 8 minutes:

I just have one last question. I printed out both the component side and the copper side of PCB. How do I print the un-mirrored version of the copper side or both of the sides as one?

Added after 3 hours 36 minutes:

Bump. :|

 

[IanP]

pic16f877 with 20 mhz crystal circuit

I am afraid you can not create a mirror image of this drawing.
If you want to watch it this way use the same method as medical practitioners use for reading X-Rays: place this drawing on a window and watch it from the other side ..
Regards,
IanP

 

[fanir]

pictures of jdm for pic16f877a

Cheers Ian. Anyway, I've got a small question. In this picture below,

**broken link removed**

I've marked in red, what are those? I know they need to be soldered but where does it go? Ground? :|

Thanks in advance.

 

[IanP]

pic16f877 circuit designing help

You are right, they are connected to ground ..
Some designers prefer to connect a pad with ground with, say 4 tracks, and these pads are just easier to solder as the heat is hardly transferred to surrounding copper ..
Regards,
IanP

 

[fanir]

pic16f877 footprint

So I just solder it to main ground which is?

Oh Btw, you've been a great help Ian. THANKS! THANKS ALOT FROM SINGAPORE!

 

[IanP]

bend db9 stripboard

Main ground always runs back to both voltage regulator U2 pin2, and U3 pin2 ..
(see: **broken link removed** ) ..

Thank you for greatings from Singapore ..

Regards,
IanP

 

[fanir]

bend db9 pins stripboard

Sorry Ian, but are you saying that all grounds are at pin 2 of the IC? I don't quite understand. Sorry.

One more thing, I have to place a DIN9 male serial port on my veraboard but the pins there are not compatible with my veraboard. I'm thinking of plugging another connecter to both 4pin and 5 pin to the DIN9. Possible?

 

[fanir]

db9 veroboard

Bump? :|

 

[IanP]

pic16f877a main circuit

In your circuit you have only one ground, and try not to create a ground loop around veroboard but run the ground wire in "star" configuration, and the centre of this "star" should be around pin 2 of the voltage regulator ..

DIN9: dou you mean DB9?

I would use right-angle PCB mounted DB9 connector, drill additional holes in veroboard and just wire it up ..

Regards,
IanP

 

[fanir]

Thanks a lot mate, but is it connected in a manner like this?

**broken link removed**

Also, is it possible to do a mount out version such like this?

**broken link removed**

 

[IanP]

Yeah, that is all right ..
Try to "lay" wires in certain order, so if you make a mistake they will be easy to follow .. it is good idea to lay them X-Y and not accross ..
Connectors can be connected in-line on wires, but try to make this circuit looking neat .. aesthetics is also important ..
Regards,
IanP

 

[fanir]

Cheers mate, I know I've been asking loads of questions but I really need help here and I really appreciate all the help you've given.

ONE LAST THING[I hope]. , how does one program a PIC? I 've been from this site

**broken link removed** to this

http://www.ucapps.de/mbhp_jdm.html

Do you need to make another circuit based on the sites as a programmer for my PIC?

 

[IanP]

These circuit are very simple, so it is probably more practical to build separate circuit for programming PICs ..
In future you can use it in other pojects ..
For comparison check out these links ..
http://www.voti.nl/wloader/index_1.html


Regards,
IanP

 

[fanir]

DIN9: dou you mean DB9?

I would use right-angle PCB mounted DB9 connector, drill additional holes in veroboard and just wire it up ..

Regards,
IanP

Hey mate, could you explain a little further, sorry for being a pain.

 

[IanP]

DB9 (see pictures below) footprint does not match 0.1" grid, but if you gently bend some pins or drill new 0.8mm holes for pins and 3mm holes for shell mounts you will be able to fit and solder this connector directly to veroboard ..
Regards,
IanP

 

[fanir]

Cheers mate, got that sorted out. Got one question though, I'm doing the programmer JDM [link above], but I accidentally bought a 15K resistor instead of a 1.5k resistor. Any ideas? I can't go buy as its quite far from where I live. .