Different results from usb and direct power

I am running an openmv H7 Plus and have an Edge detect TF Lite model that has ~98% accuracy. I am also doing a rectangle detection and taking a pic and writing the response from the model to a txt file on the sd card. When I run connected to the usb interface, i get the expected results, but when i run connected to an arduino via I2C using RPC and powered externally, i get a different response, of no detection at a much higher rate. I am receiving the rpc response to the Arduino from the H7 without issue.

Any ideas on this. I am powering the H7 with a 4xAAA power bank and a common ground to the arduino.

Hi, not sure, it sounds like the COMs might not be working like you think. Do the devices share a ground connection?

Yes they do have a common ground

We are receiving a char result from the openmv to the arduino. I am receiving one of the 5 result characters which makes me beleive that the communication is working OK from the H7 to aruino, but it is incorrect at a much higher (50%) rate than when using a direct connection to the openmv via usb.

To test, I just modify the same code and print to the serial terminal rather than setting the register_callback. The rest of the code is identical.

Hmm, well, I don’t really have enough information to suggest something.

From a debugging standpoint I would just eliminate the vision part of the code for now and just verify the communications interface works. Send like a large structure via RPC and verify that’s working reliably at the speed you expect. Then add the vision back in.

Also, remember that the camera draws power. Make sure your power system can handle the 150mA or so it requires.

Thank you so much for the assistance. The product is amazing. Also thank you for the RPC library. That is fantastic.

So it may be a power issue since the aaa bank really only outputs 100ma or so. I am looking for a better battery solution. I have read that you recommend 6V and that the usable range on the device is either 3.6 - 5V or 5-7V depending on the post. A single lipo cell is 3.7 so 2 would be too much at 7.4. Is a single lipo cell sufficient from a voltage point of view.

Yeah, the voltage input range is kinda bad for this version. We will have this fixed soon with new shields. Anyway, I recommend a 3.7V LIPO connected to the camera’s LIPO connector. I can run off of that.