PIC Circuit Board

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srpott40

New Member

• Mar 9, 2013

• #1

I have recently finshed programming a PIC16F84A, which is working perfectly on a PIC Test board, however I have tried to make a PIC Board of my own and can not get the PIC to work. I have port A set as inputs and Port B as outputs (wired up), And pins 14 to + v's and pin 5 to ground what else do I need to connect, and do i need an external clock, (I have the clock setting set to XT)

 

Ian Rogers

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Most Helpful Member

• Mar 9, 2013

• #2

Pin 4 (MCLR) should have a 5 -10k resistor to 5v.

A 4mhz xtal on pins 15 and 16 will help...

 

ronsimpson

Well-Known Member

Most Helpful Member

• Mar 9, 2013

• #3

If you want the PIC to work like it does on a PIC test board then you need to make your board the same as the test board.

Watch the reset pin!

You need to look up "XT" and see what it means. OR You could rip out the clock on the PIC test board and see what happens.

 

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srpott40

New Member

• Mar 9, 2013

• #4

Ian Rogers said:

Pin 4 (MCLR) should have a 5 -10k resistor to 5v.

A 4mhz xtal on pins 15 and 16 will help...

Click to expand...

Ok thanks for that and does it matter ehich of the 3 pins from the clock goes into pins 15 + 16 (the middle is ground I think)

 

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heydonms

Member

• Mar 9, 2013

• #5

A crystal only has two pins, if you have three then it is probably a ceramic resonator. I would start by reading the datasheet for your PIC and your oscillator.

 

Ian Rogers

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• Mar 10, 2013

• #6

1 and 3 go to the pic whilst the middle goes to the ground...

 

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srpott40

New Member

• Mar 10, 2013

• #7

Ian Rogers said:

1 and 3 go to the pic whilst the middle goes to the ground...

Click to expand...

Does it matter if pin 1 goes to pin 15 or 16, or would that not make a difference?

 

Ian Rogers

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• Mar 10, 2013

• #8

Pass!! Look at the datasheet of the resonator you have... Sparkfun has datasheets https://www.sparkfun.com/categories/88

 

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srpott40

New Member

• Mar 10, 2013

• #9

Ian Rogers said:

Pin 4 (MCLR) should have a 5 -10k resistor to 5v.

A 4mhz xtal on pins 15 and 16 will help...

Click to expand...

so what should be the voltage on this pin

 

Ian Rogers

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• Mar 10, 2013

• #10

What pin.... Pin4?... This should be 5v.. there is internal capacitance, so if a 5k resistor is used the Vdd climbs to 5v slower than the power pin... I AWAYS use a 10k just to be sure..

 

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srpott40

New Member

• Mar 11, 2013

• #11

Also any ideas on the reset pin or is that pin 4

 

Ian Rogers

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• Mar 11, 2013

• #12

That was the topic of my last post....PIN 4!!