OV5640 help needed! No PCLK signal

I am working on a project involving cameras using a Zynq FPGA on a Digilent Zybo board. I can successfully get a response from an OV7670 by configuring it via SCCB. Even without configuration the OV7670 provides a PCLK and drives the data pins as long as I provide it an appropriate XCLK signal. I have recently bought an Arducam OV5640 module. The documentation that I have read so far about this module suggests that I can still use 3.3V logic. I get no response from this module when providing a 12-25MHz XCLK signal. Can someone point me in the right direction and make me aware of what I may be doing wrong? Is it really 3.3V logic or should it be less? Is there some power-up sequence that I am not aware of that I should be doing differently than the OV7670?

Any help will be much appreciated. I am really stuck and it is well known that Omnivisions documentation is far from complete.

The product briefs that can be found indicate the I/O is 1.8/2.8V so with 3.3V you might have already damaged the part already.

- - - Updated - - -

It also looks like there are datasheets for the part you just need to justify your need for them. Try filling out the form for datasheets.

Thanks for your quick reply. I guess I should order a new one just incase. Should I be using a 75R resistor on each of the pins then?

malkauns said:

Thanks for your quick reply. I guess I should order a new one just incase. Should I be using a 75R resistor on each of the pins then?

Click to expand...

Uh, no, you should instead read about level translation https://www.eetimes.com/document.asp?doc_id=1231111. Using a voltage divider (not a single resistor) will work but only for dropping from 3.3V to 1.8V (it will also burns power when in the high logic state. Going the other way you'll have to use a transistor as the threshold for a logic high in 3.3V LVTTL is 2V (Vih), which is higher than the 1.8V output voltage.

If you don't follow anything I've posted then you probably need to do a lot more reading about digital design and how to read datasheets before just wiring things up (and hoping it works).

Would something like this work?: https://www.kr4.us/Logic-Level-Converter-Bi-Directional.html?gclid=CK_S3Pzamc4CFQt_vQodt_sOhg

From the description it seems like it should work, looks like it's using the transistor method I mentioned earlier. Make sure you take a look at the hookup guide link on that page.

Thanks for your help. I've ordered it and a replacement OV5640 just incase. Much appreciated!