Camera in low power mode nrf52-ble-image-transfer-demo

[Paul M.]

Hello everyone!
I want to evaluate the exact power consumption from the camera (Arducam Mini 2MP OV2640) using the nRF52840-DK as well as its SDK with the nrf52-ble-image-transfer-demo. 

However, the power consumption is constantly high, which must be the camera so I'd like to put it to sleep when not needed. Does anyone know how I could do that?

Thanks in advance!

Paul

[ovrebekk]

Hi Paul

How low power do you need it to be? 

I tried to check the datasheet for the module if there was any description of a sleep mode, but all I can see is a reference to a low power mode that draws 20mA, so not really low power...

Worst case you would need to power gate the whole module, by supplying power through a transistor, so that you can simply remove power to the sensor when you don't need to use it. 

With some luck someone in the community will know more. 

Best regards
Torbjørn

[Paul M.]

Hi, thanks for your help! Yes, I have thought of powering the camera through a transistor too, however, if the camera loses supply during usage, she won't initialize anymore. Also, the code keeps crashing if I put another camera_init() in the code, say every time I would want to take a picture.
Do you happen to know a solution here?

Thanks in advance!

Paul

[ovrebekk]

Hi Paul

The camera_init() function isn't designed to be run multiple times. You would have to implement some kind of camera_uninit() function, that disables all the peripherals configured by camera_init() so that they are ready to be initialized again. 

Alternatively you would have to split the camera_init() function into two functions: One function that initializes the nRF52 peripherals (SPI and TWI), and a separate function that runs through the init sequence of the camera. Then you can run the first function only once (initializing the nRF52), and run the second function every time the camera module has been disabled and re-enabled. 

Best regards
Torbjørn