SparkFun Forums

[Patroclos]

Hi,

I have designed a PCB to operate C3188A with a PIC18F452. First of all, I have designed the system on a breadboard and everything was working fine. The image is sharp and colored. So I decided to print a circuit by using the same connections that I used on the breadboard. The PCB version of my system is also working fine except the images are a little blurry. All connections of both the PCB and breadboard are the same, I have also checked for any noise induced by clock tracks with an oscilloscope but there doesn't seem to be any noise also. So what might be the problem does anyone have any idea or suggestions??

By the way, I'm writing down the links of the images that are taken from PCB and breadboard. You can easily realize the noisy contours on image taken by from PCB.

PCB image : http://atlas.cc.itu.edu.tr/~baltacit/aksam1karttan.bmp

Breadboard image: http://atlas.cc.itu.edu.tr/~baltacit/tam_renkli5.bmp

Thanks!

Taskin Baltaci

[reklipz]

It looks like it's using a smaller color pallet and dithering the image on the PCB.

Are the two running the same firmware?

[Patroclos]

hi reklipz
I'm using the same firmware. Both pcb and breadboard have the same parts and code.
What I don't understand is, breadboard is a harsher area for a system(in means of noise) but in this case the pcb looks problematic

[jasonharper]

Do you have plenty of bypass capacitors on the PCB? You might get by with less on a breadboard, due to their large stray capacitance.

But really, this looks like a settings difference. Does the camera module have any options that you aren't explicitly setting, that might be undefined on power up?

[etracer]

The PCB image was captured with fewer colors per pixel (fewer bits for each RGB value).

Looks like a configuration problem to me.

[Patroclos]

jasonharper you're right I've got more capacitors on PCB but they are mostly 0.1uF capacitors used to suppress any peak voltage values. I use one capacitor for each chip.

I have written the GUI which I used to capture image from camera. When I run the GUI, it makes a default configuration for the camera at startup. There's no difference in configurations. Both PCB and breadboard is configured same.
I think the problem is a hardware issue but I couldn't resolve it. I mean I have checked the registers of camera too. They are configured as they should be. So color depth should be the same, furthermore there's only one RGB mode of camera.

[bigglez]

The PCB version of my system is also working fine except the images are a little blurry. All connections of both the PCB and breadboard are the same, I have also checked for any noise induced by clock tracks with an oscilloscope but there doesn't seem to be any noise also. So what might be the problem does anyone have any idea or suggestions??

Greetings Taskin,

It's hard to know the difference from your two images as they
are of different subjects and under different lighting.

Can you submit two images of the same scene (one by proto,
one by PCB) for side by side comparision? A standard TV
test card image would greatly help in identifying errors.


Also, how are you displaying the data from the camera
module? Are you using the digital data or the analog video
output?

The camera can operate in either 8 bit or 16 bit modes, are
you sure the camera mode is the same for each version
(proto and PCB).

On the PCB design have you checked for shorted or open
traces that would reduce the digital data resolution. Are you
sure the data bus (if you are using the digital output) is
mapped one-for-one? Swapping or dropping bits would
reduce the resolution of the image data.

Comments Welcome!

[Patroclos]

Hi,

thanks for all replies, I have solved the problem. The issue is based on soldering I think. Because I have printed a new board yesterday and soldered them carefully and it has worked as expectedly. The images it produces are in breadboard's quality. So, it looks as if the problem is due to poor soldering. But still it looks a little strange to me, I mean what kind of poor soldering might cause such a problem?

Thanks!

[bigglez]

The issue is based on soldering I think. Because I have printed a new board yesterday and soldered them carefully and it has worked as expectedly. The images it produces are in breadboard's quality. So, it looks as if the problem is due to poor soldering. But still it looks a little strange to me, I mean what kind of poor soldering might cause such a problem?

Greetings (No Name supplied),

As I pointed out earlier:

On the PCB design have you checked for shorted or open
traces that would reduce the digital data resolution. Are you
sure the data bus (if you are using the digital output) is
mapped one-for-one? Swapping or dropping bits would
reduce the resolution of the image data.

Once again, if you make pictures of a standard test
pattern image (instead of random PIX of your cube)
we can do a better job of diagnosing your image
artifacts.

Comments Welcome!

[Patroclos]

Hi bigglez,

Thanks for the advice, next time when I test my system I'll do as you said. I'm actually thinking of resoldering each piece on my older problematic board. Then take images to see if it got better. I'll send the images after my repair attempt.