Count or detect features


I have product that has 3 dots on the lower right edge.
What I want to achieve is to determine whether the product has the 3 dots. With e.g. blob detection, blob counter or pattern recognition. I have done these in the past with e.g. congnex cameras/patMax.

I will like to trigger the camera to acquire an image with one of the IO pins, then read the output i.e. pass/fail with another I/O pin (i.e. High/Low pin state). As an added bonus, it will be nice to have another pin to check if the camera has given a result (i.e. turn pin low on acquire image request and turn it High when there is a result).

Is it possible to achieve this with OpenMV3 R2? If so, what will be the relevant examples I could start with? I have a couple of the cameras at home and I will like to try a few projects with them. I am new to OpenMV and started learning uPython.

I will be glad if you could tell if this is achievable and if its going to be too complex?

Thanks in advance.

Hi, this is really easy.

Just see the color tracking examples, tune them to work, and then checkout board control examples to add I/O pin support.

Thanks very much for the hints. I’ll get working on it.

Cheers mate.

BTW, I discovered one of my OpenMV boards is no connecting to the computer. The older software version is able the flush the firmware successful, but is unable to connect after that. I get the leads blinking different colours, the drive opens and shows the files on the hardware, but is unable to connect.

Other two spare OpenMVs are connecting fine. All 3 are from the same purchase batch.

Hi, is the new IDE able to program it? The new IDE has a lot of additions to recover older H7 boards. Please go though the DFU bootloader update and etc. with it.


Yes I tried with the new IDE 4.0.1 and it gets struck at Erasing… 78% then it times out (Timeout Error!).

With the older version 2.9.2. its able to update bootloader etc., after that I get connection error. Also with the IDE 2.9.2 I get the blue light blinking twice a second when I connect power. It also shows up in windows device manager as "OpenMV Cam USB COM Port (COM7). But when I hit connect, it says “No OpenMV Cams found!”.


Now with the new IDE I get the error “Cannot open DFU device 0483:df11”.

Hi, which board is this?

I guess STM32?

Please go into your device manager and find the STM32 DFU board and uninstall the driver. This issue happens because the DFUSE driver is conflicting with the DFU driver. The IDE has a mitigation in it to switch which bootloader is uses to get past this issue. So, I’m not sure why this error is happening. However, this is the fix.