I know we have some code ported to the nRF52 for the Arducam mini 2MP which uses SPI (data) and I2C (control) to communicate with the camera. If this is what you look for I will ask if we can make it public.
UPDATE:
Here is an example for PCA10040 or PCA10056 for ArduCAM mini 2MP:
The example do not use the standard SDK drivers, but custom ones written in C++. The cpplib folder have to be placed under nRF5_SDK_13.0.0-1.alpha\components. The ArduCAM folder should be placed under nRF5_SDK_13.0.0-1.alpha\examples\MyProjects or similar folder.
See the ArduCAM::spiTwiInit() function for which pins are used for the ArduCAM mini 2MP. If the VCC and GND pin on the ArduCAM are bent, the module can be directly connected in header P4: P0.22-P0.27 on PCA10040 (nRF52 DK), and P24: P1.09 - P0.13 on PCA10056 (nRF52840 PDK).
IMHO the OV7670 is a nightmare to interface to directly. Its not strictly I2C its SCCB, but they almost operate the same. The data from the OV7670 is streamed and you have to be able to clock it into RAM at a pretty high speed (Mhz).
It only barely works at all on the 16Mhz AVR processor, and even on devices like the STM32 @ 72Mhz I could not use an interrupt to read the data.
However, it looks like the Arducam has got around this by having Altera FPGA to act as a frame buffer and simplify the control etc.
IMHO the OV7670 is a nightmare to interface to directly. Its not strictly I2C its SCCB, but they almost operate the same. The data from the OV7670 is streamed and you have to be able to clock it into RAM at a pretty high speed (Mhz).
It only barely works at all on the 16Mhz AVR processor, and even on devices like the STM32 @ 72Mhz I could not use an interrupt to read the data.
However, it looks like the Arducam has got around this by having Altera FPGA to act as a frame buffer and simplify the control etc.
