Capturing a 1 MP image

Thanks for bringing OpenMV H7 into the world, especially as an open source project. I’m looking at an application to capture a 1MP image from the AR0135 image sensor with OpenMV. For this we would like to add a driver for this sensor. Any guidelines that we can follow for this?

Also I see that the max resolution is 1600x1200, but I guess this is only for JPEG stream. Also in another question I see that a max resolution of 400x400 is supported because the biggest chunk of SRAM is 512 kB in H7. Anyway to support 1MP images? Would it be possible to DMA each row first to the AXI 512 kB SRAM and then when the next row is being sent the first row is sent to SDMMC1? This would mean a lower buffer size is needed to stream the data to the SD card, though I guess it’ll need quite a bit of synchronization.

Thanks and regards, Prithvi

Nothing official, you’d have to look at how other sensors are supported. For example, someone just added support for OV5640, it should be a good example (if you ignore all the I2C stuff that was needed to support 16bit reg address).

The max resolution is limited by the 512K memory used for the framebuffer. The DMA supports a linked list mode, it should be possible to read the frame into two memories (SDMMC is slow), but we’re using all the memory blocks for different things. We’re going to release an SDRAM version soon, if you want higher resolution you can use that.

Thanks a lot Ibrahim for the inputs! In this new version with SDRAM can you also think about adding a 1.8V voltage translator for the SD Card so that they can be used in the UHS-I mode for much faster communication.

That would require more engineering work that we have capacity to do. If someone contributed to the project with that tech it would be appreciated however.

Yes, developing the firmware would take quite a bit of effort. The situation now is the only boards with this are the EVAL boards which cost a bomb. Only if there was a low cost board to develop this firmware on. :wink:

How about adding the translating circuitry to this version and then developing the firmware with the help of the community after they’re sold. As far as I understand in the translator not changing the voltage won’t need any other change in the firmware. We’re working on a camera trap and we eventually (2-3 months from now) will write this firmware if we can’t find it elsewhere.

Cheers, Prithvi

Um, it’s possible to add level shifter as requested, the DRAM version design is not fixed yet.

Um, okay, so, email us at and I will connect you to Kazhi who is leading the design. You can work with him to add this part to the board. We are buying these units through SingTown as the DRAM version is a co-project.