Change the manual ISO value on the camera
camera_error_t camera_set_manual_iso(camera_handle_t handle, unsigned isovalue)
Use this function to set the manual ISO value. The value that you set using this function is only applied when the exposure mode has been set to allow manual ISO settings using camera_set_exposure_mode(). You can use the camera_get_supported_manual_iso_values() function to determine the range of valid ISO values that you can use.
For more information regarding when these manual settings take effect, see camapi_manual_settings and camera_exposuremode_t.
The viewfinder must be running before calling this function.
CAMERA_EOK when the function successfully completes, otherwise another camera_error_t value that provides the reason that the call failed.