PCLK out of OV9650 Camera Module

[EC.Engineer]

Hi all,

I am facing a problem while trying to interface the OV9650 camera module with PIC32.
The PCLK pin of the camera module is giving out unexpected output. The difference between the high level and low level of the PCLK clock is so low that the microcontroller cannot distinguish between. View attachment A0001DS.BMP
Please check the attached waveform. The high level is aroung 2.9V and the low level is around 2.8V.

How can I solve this problem and bring the low level down to 0 V?


Thanks

 

[keith1200rs]

Check to see whether you are loading the clock - for example by not having the PIC input configured correctly.

Keith

 

[EC.Engineer]

The PIC is properly configured for input. And I also tried checking the PCLK directly on oscilloscope without connecting the PIC but it is still the same.

Tried connecting pull-down resistor, pull-up resistor, series resistor but still the same. Connecting high value of series resistance is actually decreasing the difference between the two levels and making them almost the same.

Low values of pull-down resistors are bringing both the levels down. I need to bring only the low level down and keep the high level same.



Also, how can I remove those spikes?

 

[keith1200rs]

The only datasheet I have is 'Preliminary' but I wonder if there is a mode where the PCLK is not driven? It may be worthwhile checking some of the commands which affect PCLK. Also, contact Omnivision. Could there be a short to an adjacent pad/track or a bad connection?

Keith