I recently joined a local (Omaha) group that plans on creating and racing autonomous cars. It got its inspiration from diyrobocars.com. I bought an OpenMV M7 camera off of SparkFun on CyberMonday and received it yesterday.
Read the instructions first
OpenMV has documentation on how to set up the hardware and software. I didn’t realize there were some things that I should have done before diving in. The first was to clean the camera IC. I did this later and I don’t think it helped in any way. The second was updating the firmware which did help. One thing that kept giving me errors when running the hello world script was that it was complaining about the time variable passed in to the skipframes function. The old firmware didn’t support the named parameter. All I had to do was delete the name and it worked. But after updating the firmware the name was accepted.
Another thing that puzzled me at first was why the image was not in focus. Well, had I read the instructions I would have learned that I had to twist the lens to focus it.
I wish the instructions had pictures because I was too afraid to remove the lens housing. I wasn’t 100% sure it was the entire black piece. It wasn’t until I found some images on this GitHub page that I was confident enough to take it off.
I need a microSD card. There are a lot of example programs that can save images but only if you have an SD card. I couldn’t even get the DonkeyCar program to run. It would just sort of hang and then disconnect the camera. At this point, I think it has to do with the size of the program.
Not All Screwdrivers Are Created Equal
Why would one screwdriver work for the lens mount screws not work for the focus screw? Also, the screw to hold on the lens took more force than I thought was necessary. Perhaps it needed to create threads in the plastic, but I had to tighten the screw before the lens wouldn’t move.
Do I need a separate servo “shield” if the board already has servo controls? It’s been about 20 years since I learned pulse-width modulation so I need to read up on it. During our meeting it sounded like I needed a separate board, but it looks like the camera supports it. Maybe that was for the Raspberry Pi version.
I have never done any serious soldering. But to get the header pins on the camera I will have to. Or get someone from the group to do it.
Here are the supplies I used:
- Isopropyl Alcohol
- Lens cleaning cloth