Can anyone explain the BreadBoard layout for this...

[Blueprint]

Ok, the "technical" diagram is here:

http://techref.massmind.org/techref/piclist/cheapic/bincnt.htm

and I have set up my breadboard, but something's not working. The PIC is all coded up ready to go, its in the centre of my board... but something's not working right .

I must admit, I don't much understand the right side of the "technical diagram". You can see my version of the breadboard (sorry for the bad image!) at the following URL:

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Any advice/help would be much appreciated.

Thanks

 

[The Real MicroMan]

looks like your VDD and VSS lines are switched

 

[williB]

i would like to help, what dont you understand about the right side of the diagram??

 

[YAN-1]

I was looking at the circuit you are supposed to build. Shouldn't the capacitors of the crystal be connected to ground instead of Vdd?

 

[Nigel Goodwin]

I was looking at the circuit you are supposed to build. Shouldn't the capacitors of the crystal be connected to ground instead of Vdd?

It makes no difference, Vdd and Vss are at the exact same potential as far as AC is concerned - so it should work fine either way.

 

[Blueprint]

Ok i've tken 6 shots of my breadboard as it is at the moment. Please help, it's not working. Don't worry there are no resistors there yet:

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Thanks.

 

[Jay.slovak]

Scheme seems fine to me, try to place crystal closer to the PIC and shorten it's leads (not PICs leads, the wires that connect PIC and crystal).

 

[Nigel Goodwin]

Scheme seems fine to me, try to place crystal closer to the PIC and shorten it's leads (not PICs leads, the wires that connect PIC and crystal).

I agree, the layout is absolutely horrible - personally I don't like (or use) breadboards, and this gives a good example of why not 8)

You should keep leads as short as possible, particularly round the crystal and associated capacitors - check the veroboard layout for the 876 board in my tutorials, you will see how close I place the crystal to the pins!.

 

[williB]

Just a thought, have you got the diodes hooked in correctly..?
also ,you can use the resistors, in place of the wires, going from the outputs to the diodes ..
so from any one output pin you would have a resistor , a diode , and a wire to ground..

 

[Jay.slovak]

Scheme seems fine to me, try to place crystal closer to the PIC and shorten it's leads (not PICs leads, the wires that connect PIC and crystal).

I agree, the layout is absolutely horrible - personally I don't like (or use) breadboards, and this gives a good example of why not 8)

You should keep leads as short as possible, particularly round the crystal and associated capacitors - check the veroboard layout for the 876 board in my tutorials, you will see how close I place the crystal to the pins!.

Nigel, I never had a problem with my Breadboard. I know it's not very appropriate for HF stuf (like crystals ) but If you try to make connections short and place it far from any other HF noise, it will work fine. This is a trade-off for simplicity of usage 8)

 

[JFDuval]

Hello!

Is it me or on this schematic, the two quartz capacitors are going to the positive? Shouldn't they go to the GND?

 

[eblc1388]

Hello! Is it me...... ?

It is you. See posting above by YAN-1 & the answer by Nigel.

 

[Blueprint]

Hi,

I REALLY appreciate all of your advice! I'm at work at the moment, so can't change anything yet, but if you could let me know what I need to change when I get home I'd be most grateful.

So far I see I need to move the crystal closer... shorten the wire lengths. I'm not using any resistors yet either. So yeah, if you could let me know what steps to take when I get home that;d be great. Is the wiring correct?

Ed
Design & Marketing Manager
www.svp.co.uk

 

[mechie]

Deliberate mistake ?

Looking at the original drawing of your layout and the third photo (detailing the crystal circuit area) ...

Do I see a wire from the PIC pin 15 going to the wrong side of a capacitor (ending up connecting to the power rail) ?

(A wire from breadboard column 15 to column 4 (should be column 5) :?:


As far as breadboards are concerned I use them for prototyping, I always try to keep the crystal wires short and away from any source of interference but I have never had any problems (as per Jay's posting).

I think if you move this ONE wire it may just burst into life (you need some LED resistors though!)

 

[Blueprint]

Haha thanks... sod the LED's if they blow, they blow... Im screwed when it comes to choosing resistors, i got a lucky bag from Maplin, but i calculate all of them to be over 100mA which doesn't help seeing as i'm only using 3.5v to start with, all the other electronics and shizzle... I need a low mA resistor. It'll be ok.

(I know that's a bad attitude to have, but i'm desperate to get it working, without using too high-a-resistor giving me the impression it's not working!).

Thanks again. Which I could give something back in return but i'm shocking at this stuff... just learning!

Ed
Design & Marketing Manager
www.svp.co.uk

 

[Nigel Goodwin]

Haha thanks... sod the LED's if they blow, they blow... Im screwed when it comes to choosing resistors, i got a lucky bag from Maplin, but i calculate all of them to be over 100mA which doesn't help seeing as i'm only using 3.5v to start with, all the other electronics and shizzle... I need a low mA resistor. It'll be ok.

This could be one of the problems? - you obviously have VERY little electronics knowledge - resistors are measured in ohms, NOT in mA.

Resistor values for LED's are not at all critical, and different values (within reason) will only alter the brightness.

I would suggest using something in the 'hundreds', anything over 100 ohms and under 1000 ohms should be fine, aim for about 470 ohms, which is yellow, violet, brown, gold (for a 5% resistor).

But DON'T connect the LED's without resistors, as well as killing the LED you could kill the PIC as well.

 

[Blueprint]

Ok thanks for that advice. I did mean to say Ohms, but didnt realise it could damage the PIC. I've tested the PIC and it's still alive (thankfully!). All "resistored" up and raring to go, just gonna try and connect the rest now...

Wish me luck...

 

[Someone Electro]

an 220 Ohm resisor and it will run any LED (100 Ohm if you want them bright)

I put the crystal on the same row of the breadbord as the PICs OSC pin is. 32Khz is not much so it shodnt mess up whith long wires to much.

Im runing it 16Mhz and it runs no problem on an breadbord.

Do you have the PIC set to an low power oscilator or it may be overloading the crystal.

Awww the old obsolete PIC16F84.It has no internal oscilator.The new PICs have internal oscilators so i dosent need an crystal to run.And they will automaticly switch to the internal osc. if the crystal fails.

Did your write your program right?

btw:
Hope you didnt use an micrwave to burn your program on. lol :lol:

 

[Blueprint]

Haha, just sorting out my resistors now, i'm home. I'm actually using a PIC16F84A... I take it that doesnt have an internal oscilator?

I'm using the code from this site (and the wiring layout):

http://techref.massmind.org/techref/piclist/cheapic/bincnt.htm

I'll look for a resistor between 220-100Ohms. Does it matter if I use four resistors (i.e. 4 x 100Ohm resistors = 400Ohms, therefore I should use weaker resistors...or?) I believe the diagram shows the resistors/LED's in parallel right? So the Ohms don't accumulate?

I'm laying it out exactly as in the diagram shown on the above site.

EDIT: No, i'm using a PIC programmer to program the chips... i'm not using the oven method for PICs.

 

[Jay.slovak]

Haha, just sorting out my resistors now, i'm home. I'm actually using a PIC16F84A... I take it that doesnt have an internal oscilator?

No 16F84 is very old chip. When it was designed no PICs had internal oscilators

I'll look for a resistor between 220-100Ohms. Does it matter if I use four resistors (i.e. 4 x 100Ohm resistors = 400Ohms, therefore I should use weaker resistors...or?) I believe the diagram shows the resistors/LED's in parallel right? So the Ohms don't accumulate?

100 ohms will be fine, do not lower it or you will burn the LEDs.