PIC Devlopment board

[Bob Parihar]

i want to create a small handy PIC16f877a development board for different peripherals.
could someone helps me by giving the exact circuit diagram for this controller

 

[Wp100]

Hi,

Not sure what you mean by "exact circuit diagram for this controller", the datasheet is no. 1 port of call

Do you mean a basic circuit to simply run a 877A or a full dev board, the latter is really down to what devices you want to attach to it, but without knowing what they are we cannot say ..

Also what programmer are you intending to use with it ? A Pickit2/3 or similar microchip device will allow you to both program and hardware debug your code.
To this end its better to design your board so pins Mclre,PGC and PGD are dedicated to the programmer/debugger.
If you have a Pickit etc then see its user Guide on how to connect up for ICSP.

Have you done a basic diagram yourself, if you post it with some more details we can help more.

Edit - here is a decent looking complete circuit for a 877a / 4520 ( pin identical for this purpose)
https://www.extremeelectronics.co.in/pictutorials/images/pic18f4520_usart_schematic.gif

 

[Ian Rogers]

You need to specify the peripherals....

If you visit Nigel's tutorials, you can see how he did it by making connecting systems..

Link is in my signature... All the ASM tutorials were re-written by me into C.. Links also in my signature.

 

[absf]

You can either buy this board built or build it yourself. The schematics is included under the download section further down the page..

https://www.cytron.com.my/viewProduct.php?pcode=SK40C&name=Enhanced 40 pins PIC Start-Up Kit

Allen

 

[Bob Parihar]

simply

You can either buy this board built or build it yourself. The schematics is included under the download section further down the page..

https://www.cytron.com.my/viewProduct.php?pcode=SK40C&name=Enhanced 40 pins PIC Start-Up Kit

Allen

i just want to know the circuit diagram for a 40 pin DIP pic16F877a micro controller..like
how the external crystal oscillator is attached with the controller and the reset button circuitry and the port connections etc.
so that i can do its interfacing even on the breadboard with different periphrels

 

[jjw]

Maybe you should download the datasheet of pic16f877a

 

[Wp100]

simply


i just want to know the circuit diagram for a 40 pin DIP pic16F877a micro controller..like
how the external crystal oscillator is attached with the controller and the reset button circuitry and the port connections etc.
so that i can do its interfacing even on the breadboard with different periphrels

Hi,

Does not that diagram I show in #2 meet your needs ?

Its much better if you can place all those parts on a soldered board and use a breadboard for the i/o devices to the pics ports.

Just say what is not clear and we can help more.

 

[Bob Parihar]

how important are exact values on the capacitors, and is the crystal

 

[Wp100]

Hi,

You can have a variety of crystals, see the 877a datasheet for the range, however would suggest 4mhz is a very popular choice with 22pf capacitors.

You could use 15pf or 27pf caps but they would alter the timing slightly, better to stick with the specified values, they are a common enough.

8 ,16 and 20 mhz are frequencies also used quiet often, though for 16 and 20mhz the circuits will show smaller value caps, typically 10 or 15pf .

Have you any thoughts on a particular frequency ?

 

[Bob Parihar]

Hi,

You can have a variety of crystals, see the 877a datasheet for the range, however would suggest 4mhz is a very popular choice with 22pf capacitors.

You could use 15pf or 27pf caps but they would alter the timing slightly, better to stick with the specified values, they are a common enough.

8 ,16 and 20 mhz are frequencies also used quiet often, though for 16 and 20mhz the circuits will show smaller value caps, typically 10 or 15pf .

Have you any thoughts on a particular frequency ?

yes iam trying to operate on 20 mhz frequency

 

[Nigel Goodwin]

yes iam trying to operate on 20 mhz frequency

Bear in mind breadboards aren't great for high frequencies - running a 20MHz crystal on a breadboard means it has a lot of unwanted capacitance.

You can check the connections (and values) on my tutorial hardware:

 

[Bob Parihar]

Bear in mind breadboards aren't great for high frequencies - running a 20MHz crystal on a breadboard means it has a lot of unwanted capacitance.

You can check the connections (and values) on my tutorial hardware:

one question came from here.. i know its a very silly question
but i want to make shure..
since the operating frequency of PIC16f877a is 20 Mhz
i made a c code at 20 MHz in Mikro C
if i use a 8MHz crystal at the oscillator circuit.. the code won't work..isn't it? or i have to use 8MHz at starting of making a new project in Mikro C? is it?
plz help iam so confused in this frequency stuff

 

[Ian Rogers]

With mikroC you can change the crystal frequency at any time.... From the menu select.. Projects\Edit Project\ then MCU & oscillator.... Just change to desired xtal...

If you want to run your project on breadboard at 20Mhz.. Just leave off the two crystal capacitors... It should be okay as long as the crystal is close enough..

 

[Bob Parihar]

With mikroC you can change the crystal frequency at any time.... From the menu select.. Projects\Edit Project\ then MCU & oscillator.... Just change to desired xtal...

If you want to run your project on breadboard at 20Mhz.. Just leave off the two crystal capacitors... It should be okay as long as the crystal is close enough..

thanks for your concern but u didn't understand my question.. i was asking that if i configured my code at 20 MHz in mikro c and if i am using a 8 MHz crystal at hardware... this might not work? is it?

 

[Ian Rogers]

Did you read the other bit.... You can change the xtal speed in a project anytime...

If the device is already programmed, then it will need to be compiled and programmed with the new xtal setting..

 

[Nigel Goodwin]

thanks for your concern but u didn't understand my question.. i was asking that if i configured my code at 20 MHz in mikro c and if i am using a 8 MHz crystal at hardware... this might not work? is it?

It will probably work, but obviously the timings will all be completely wrong - but why would you do something so silly?.

 

[Bob Parihar]

It will probably work, but obviously the timings will all be completely wrong - but why would you do something so silly?.

actually i calculated according to 20 MHz in my code but now i figured out that i dont have 20 Mhz crystal anymore
but its ok... now i got it i have to recalculate and make another code for 8Mhz signal

 

[Nigel Goodwin]

You really need to decide what frequency you're wanting to use, and WHY! - the two 'normal' options are 4MHz or 20MHz - although obviously various ones can be used (PIC's effectively go down to DC).

Even at 4MHz the PIC will spend almost all it's time just "wasting time", only rare applications require 20MHz.