Im eagerly awaiting my OpenMV Cam H7 +. One exciting feature I am looking forward to exploring FREX mode. I see it has been mentioned several times in the forum but not explored in great detail.
A little background about FREX mode also called Global Reset Mode:
The OV5640 is a rolling shutter. Rolling shutter are not well suited for capturing objects that are moving. For example try taking a photo of a fan while it is turned on. The resulting image will be distorted. This is do to the way the shutter is exposed.
The OV5640 is a unique camera sensor as it support FREX mode. This is a feature not really found in affordable camera sensors. Here is a description from the docs:
Compared with normal(rolling) exposure mode, frame exposure allows all rows integrated simultaneously rather than row by row. It is mainly used in image capture and can work accompany with flash strobe function to increase image brightness under dark situation.
Generally, the function works as follows:
(1) Initially, the sensor is in normal exposure mode. The electrical shutter is open.
(2) User sends a frex request.
(3) Photo-diode of all pixels in all rows start precharge and the precharge will last for a given time.
(4) Until a given precharge time, the precharge phase stops and all pixels start integration.
(5) During integration, flash strobe may turn on to increase exposure.
(6) Until a given exposure time, the electrical shutter closes to stop further integration, and whole image is then start to readout.
(7) After the readout is finished, the electrical shutter opens again and the sensor resume to normal mode.
How is FREX a benefit?
Essentially the camera can mimic a global shutter sensor. In global reset mode, all of the pixels on the sensor begin collecting charge simultaneously, rather than row by row. The end of integration, however, is still delayed on the sensor row by row from top to bottom as readout takes place. One result of this behavior is a partial reduction in motion blur and other effects typical of rolling shutters.
Will the OpenMV Cam H7 + have direct access to the Frex and Strobe pins?
If the pins are not exposed will we be able to write registers to the sensor to activate FREX and Strobe?