3. Hardware Setup¶
Before connecting your OpenMV Cam to your computer you’ll want to clean the camera IC first. You’ll need some type of cloth that doesn’t leave behind strands (like a microfiber cloth used to clean eye-glasses) and some isopropyl alcohol.
- Use a screw driver to remove the two lens mount screw from the lens mount on your OpenMV Cam.
- Apply some isopropyl alcohol to a small part of the cloth.
- Rub the wet part of the cloth on the camera IC gently. Any dirt spots on the camera IC will be microscopic to the human eye so just try to generally rub down the top of the camera IC. Note that the top of the camera IC is glass.
- After cleaning the camera IC make sure the alcohol has evaporated completely and that no cloth strands were left behind. Note that we’re using isopropyl alcohol versus water since isopropyl alcohol evaporates quickly and doesn’t leave anything behind.
- Use the screw driver to re-attach the lens mount. Make sure that the set screw on the lens mount points off the top/back of the OpenMV Cam.
Next, find a micro-usb cable and connect your OpenMV Cam to your computer and then launch OpenMV IDE.
Please be gentle with the micro-usb cable. When connecting or disconnecting the micro-usb cable to your OpenMV Cam please move the cable side-to-side and not up-and-down. You can easily rip off the micro-usb connector on our first generation of OpenMV Cams (OpenMV Cam M4) with up-and-down movement. Our second generating OpenMV Cam (OpenMV Cam M7) uses a micro-usb connector with through-hole strain relief pins to be more robust.
On windows you should see some notifications about windows installing drivers and such. Wait until windows finishes installing drivers, your OpenMV Cam’s USB flash drive appears, and the blue led on your OpenMV Cam is blinking before trying to connect with OpenMV IDE.
On mac or linux please wait until your OpenMV Cam’s USB flash drive file browser window appears (you may have to click on it for the operating system to mount it) and the blue led on your OpenMV Cam is blinking before trying to connect with OpenMV IDE.
If your OpenMV Cam appears unresponsive after connecting to the computer that is okay too. If you didn’t see a green light flashing right after it was connected then we can use DFU to re-program your OpenMV Cam. If you saw a green light but no USB flash drive appeared then we can still use DFU to re-program.
Next, launch OpenMV IDE and click on the connect button (lower left-hand corner in OpenMV IDE). OpenMV IDE should then automatically connect to your OpenMV Cam. However, you may get a few different errors your first time:
- If OpenMV IDE gives you an error about not being able to find a corresponding drive to mount then you need to make sure that the USB flash drive the OpenMV Cam appears as is mounted. In particular, linux does not always amount mount USB flash drives like Windows and Mac do. You can force a mount in Ubuntu for example by clicking on the flash drive icon that will appear in the launcher menu. Anyway, after getting this error and mounting the drive just click on the
Drive:label on the bottom right-hand side of OpenMV IDE to connect to the OpenMV Cam’s flash drive after the OpenMV IDE has connected to your OpenMV Cam’s serial port.
- If OpenMV IDE can’t connect to your OpenMV Cam at all it will ask you if you have an OpenMV Cam connected to the PC. There are two possible reasons for this. First, your micro-usb cable may be a power only cable. A large number of micro-usb cables are so make sure that it’s a power and data micro-usb cable and that it’s not broken. I.e. test the cable with a known working micro-usb device. Otherwise, your OpenMV Cam’s firmware might not be working. To fix this just follow the prompts OpenMV IDE displays after clicking connect.
- If your OpenMV Cam’s boot-loader is working (green light flashes on power-on) and your computer can connect to our boot-loader then OpenMV IDE should be able to automatically update your OpenMV Cam’s firmware for you.
- If your OpenMV Cam’s boot-loader isn’t working (green light doesn’t flash on power-on) or your computer can’t connect to our boot-loader OpenMV IDE will display a “connecting” box. You can try unplugging your OpenMV Cam and plugging it back in, this may fix the issue, otherwise click cancel and then OpenMV IDE will ask if you want to use DFU to recover your OpenMV Cam’s firmware. Say yes and follow the prompts to recover your OpenMV Cam’s firmware via DFU. DFU should 100% work to recover your OpenMV Cam on Windows and should work on Mac and Linux if you installed DFU support. However, on Mac and Linux the first connection since the OpenMV Cam was plugged into your computer may fail. Just try again and it should work the second time.
Anyway, once you’ve connected to your OpenMV Cam the firmware may be
out-of-date. To update your firmware please click on the
label on the bottom right-hand side of OpenMV IDE if it says your firmware is
out-of-date. OpenMV IDE will then automatically update your OpenMV Cam’s
firmware. If there’s a problem connecting to your OpenMV Cam’s boot-loader on
your computer OpenMV IDE will try to update your firmware using DFU. Please
follow the prompts to update your firmware via DFU. As mentioned above with DFU
on Mac and Linux please try updating via DFU twice if the first time fails.
Moving on, once your OpenMV Cam’s firmware is up-to-date please run the
hello_world.py script you see in front of you in OpenMV IDE. To do this
simply click on the green run button (bottom left-hand corner) in OpenMV IDE.
hello_world.py script turns your OpenMV Cam into a webcam showing you
what it sees. If this is the first time you’ve run your OpenMV Cam the lens
will be out of focus. To focus the lens do the following:
- Make sure the set screw is not fully screwed in and that you can screw the lens in easily.
- Screw the lens in until the image comes into focus in OpenMV IDE’s frame buffer.
- Tighten the set screw on your OpenMV Cam’s lens mount to prevent the lens from moving anymore. Note that the set screw doesn’t dig into the lens threads but instead just creates a bump in the plastic preventing the lens from unscrewing anymore.
Your OpenMV Cam is ready to use now!
We require you to manually clean your OpenMV Cam camera IC and then focus the lens because it’s very expensive for us to do this currently. As we increase our production volume we’ll be able to do this eventually for you. Note that all OpenMV Cam camera ICs are cleaned before being packaged, but, since focusing is not done our manufacturer can’t tell if the camera IC is clean. The quality control test we use for each OpenMV Cam only verifies that the camera IC is connected properly and operating normally.
3.1. USB Flash Drive Notes¶
Your OpenMV Cam has a USB flash drive built-into it. This flash drive appears when your OpenMV Cam is plugged into your computer. There are a few things you should know about this flash drive:
- Windows/Mac/Linux assume USB flash drives can’t create files by themselves. So, if you create a file on our OpenMV Cam in a script Window/Mac/Linux won’t detect that the new file exists until you either reset your OpenMV Cam using OpenMV IDE (see Tools->Reset) or disconnect and then reconnect your OpenMV Cam to your computer.
- If you see a red light blinking on your OpenMV Cam while it’s connected to your computer that’s just a notification that your computer is accessing your OpenMV Cam’s USB drive.
- If you corrupt the state of the internal USB flash drive of your OpenMV Cam you can reformat the flash drive either through your operating systems reformatting tool or by re-installing your OpenMV Cam’s firmware and selecting the “erase internal flash drive” option.
- You can accidentally corrupt your OpenMV Cam’s internal flash drive state by trying to save images to the internal flash drive (i.e. using up all the space of the small flash drive because most images are larger than the internal flash drive which is only a few KB), or if power is removed from your OpenMV Cam while it’s saving something. The internal flash drive uses the FAT filesystem which has no ability to recover from partial writes due to power failure like modern file systems such as NTFS (Windows) on your PC. NTFS does something called journaling which involves writing what it’s about to do in a scratch buffer, doing what it wrote in the scratch buffer, and then clearing the scratch buffer. This allows NTFS to recover if power is lost by looking at the scratch buffer. FAT, the file system used by DOS, Windows 95/98, etc. doesn’t have this feature so if power is lost while it’s writing to a file the whole drive could be corrupted. Why use FAT then? Because it’s the de-facto standard for USB Flash Drives, but, more importantly there are open-source drivers for it and it’s not under patent protection.
- In general, avoid writing to your OpenMV Cam’s internal flash drive in a python script. Instead, just use the internal flash drive to store assets manually copied onto your OpenMV Cam while it is connected to your computer by you.
- After manually copying assets to your OpenMV Cam’s internal flash drive please use the safety remove hardware feature before unplugging your OpenMV Cam (or not, the system won’t break if you ignore doing this).
- Windows may ask to scan and fix the USB Flash Drive before mounting it. You can either say yes or no to this. Windows will generally only ask if the power was turned off on the the internal flash drive during a write. So, if Windows asks to scan and fix the drive then let it.
- Finally, if you insert a micro-sd card into the micro-sd card slot on your OpenMV Cam the micro-sd card will replace the internal flash drive for all of the above. The OpenMV Cam supports micro-sd cards up to 32 GB in size. In particular, we support SD and SDHC micro-sd cards, but, not SDXC cards which are the ones larger than 32 GB. However, this is only because SDXC cards aren’t formatted using the FAT file system. If you format an SDXC card with FAT then it may work with the OpenMV Cam. Last, feel free to save pictures/video on a micro-sd card. Just don’t do this on your OpenMV Cam’s internal flash drive.