OV5640 no PCLK signal

Using Arduino Programming Questions
1

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.

2

so the Arducam OV5640 uses a OV5640 color CMOS QSXGA (5 megapixel) image sensor and the doc states

power supply:
core: 1.5V ± 5% (with embedded 1.5V regulator)
analog: 2.6 ~ 3.0V (2.8V typical)
I/O: 1.8V / 2.8V

so if you have this product, then you probably need to deal accordingly

but if you are using the full shield they sell, then all ArduCAM’s IO ports are 5V/3.3V tolerant