Detecting position and rotation of the openMV camera relative to a computer screen

Thanks, that clears things up regarding my K matrix.

I’ve been following the discussion thread regarding the feature request for the implementation of computing homography for a set of correspondences, and it just seems to kind of end after you requested for someone to implement it. I’m not sure if its still underway, but if I were to implement it myself do I just need to port this into python?

Also, on another unrelated note, if I have 2 openMV boards would I be able to power two of them with just 1 USB cable (just powering 1 board), and connect the 3.3V and GND of both boards to each other?

Yes, I’ve told you what to do several times now…

As for your second question. Yes.

Sorry, I’m abit slow and I didn’t understand what you’ve mentioned before, I think I understand better now after rereading a couple of times.

Thanks for answering my second question, I had no idea that a single USB provided enough to run 2 boards. I assume I’ll have to save the script on board such that it automatically runs when powered up. Just to clarify, the 3.3V of the powered board goes to the 3.3V of the unpowered board, and likewise for ground correct?

One more question - after using the lens_corr function on the image to correct distortion, is it safe to assume my distortion coefficients in the intrinsic matrix are now 0?

Thanks for answering my second question, I had no idea that a single USB provided enough to run 2 boards. I assume I’ll have to save the script on board such that it automatically runs when powered up. Just to clarify, the 3.3V of the powered board goes to the 3.3V of the unpowered board, and likewise for ground correct?

Yes, but, note, this is not a “feature” that we promise will work in newer models.

One more question - after using the lens_corr function on the image to correct distortion, is it safe to assume my distortion coefficients in the intrinsic matrix are now 0?

Yeah, you could do that.

1 Like

Alright, so I take it as a “at your own risk” kinda thing… Thanks!

Hi, quick question, does the openmv gpio pins have any form of overcurrent protection?

No, I/O pins on MCUs generally don’t. Shorting them out can cause issues.

On the RT1062 the emi filters add 100ohm resistors which provides some protection. However, these causes max frequency issues so we will not be putting them on more boards.

I was intending for them to be used to power infrared LEDs, and to my knowledge I believe LEDs draw a lot of current. I have a 330 ohm current limiting resistor in series, but I’m planning to add more IR LEDs connected to the same pin, but I’m worried this would burn the pin. I was going to use the on board infrared LEDs, but since I could only find the wavelength of the IR lights but not the irradiance or power output of the in board IR LEDs, my project supervisor did not allow me to use them (he wants guidelines regarding acceptable time of exposure, acceptable infrared levels on the eye, etc for safety reasons) and insists for me to use an external one. Do you think a singular 3.3V pin would be able to power 2 LEDs?

no.
please dont attach anything directly on the pins.
Pins must be optoisolated for both outputs and inputs configuration.
I recomend to use different power supply for the leds and anything in your external circuit too…

Just to clarify, I’m powering the LEDs using 3.3V pin, not the gpio pins, does this still apply?

The system 3.3V regulator can source 2A easily for external devices.

We have an LED shield that handles 16 LEDs at the same time without issues.

1 Like

That’s perfect, thanks!

I don’t think that this is perfectl. LEDs fails over time. If a led will be shorted it will short the MCU too… It’s up to you to decide.

If you just power them with 3.3v and ground there is not a problem as soon as you dont draw to much curent. Thought that you enable them with the pins indeed…

I see, I’ll be careful not too draw too much current then!