OpenMV4-H7

     This project is a 2-layer PCB. I also open sourced a 4-layer board with the same pin sizes as the official ones. You can check it out if you need it.

     For personal DIY only, please do not use it for profit.

     The main control chip, LED1-6, 24P-FPC socket and several pin headers are missing from the BOM. The chip can be STM32H743VIT6 or STM32H750VBT6 . The latter is much cheaper than the former, but the storage space is much smaller. Both can be used. If the program is too large, it can be placed in the SD card. You can buy it on demand. LED1 2 3 4 are all 0805 packages, among which LED1 is the power indicator light, LED2, 3, and 4 are RGB LEDs respectively; LED5 and 6 are 1206 package 850nm infrared fill-in LEDs; the seat of FPC24P uses a flip-down under-connection 24P0 .5mm spacing. (The camera will come with the purchase of the seat, but it is best to buy a few more as spares)

    The FPC 0.5mm pitch 24P cable camera used in this project supports OV7725 with 30W pixels and OV2640 with 200W pixels (I haven’t tried the OV5640 with 500W pixels, so I don’t know if it will work). The higher the pixels, the lower the frame rate. I recommend it. OV7725 is sufficient and can run to 40 frames+. (Just search FPC OV7725 on a certain website)

    There is also USB with Type-C interface in the schematic diagram. If you need to make a Type-C version, delete the left side of U2 in the schematic diagram, connect the line on the right side of the Type-C interface part to the left side of U2, and then set the properties of R19, R20, and USBC1 Change "Go to PCB" to "Yes". Update the PCB and simply lay out the wires. It is very simple to only change 3 components.

    Firmware burning

    There are many methods. You can refer to the work of a great master in Kaiyuan Square. You can find it by searching for openmv in the square.

    Below is the method I use. It is easy to fail to burn the entire program with DFU, so I took a step back, burned the boot program and then programmed with OpenMVIDE. The actual test was 100% successful. The following is the specific operation process:

    Short-circuit BOOT0 and VCC; then connect it to the computer through a data cable; at this time, your computer will automatically pop up to show that an STM32DFU device is connected. The driver may be automatically installed when you plug it in for the first time; then open the DfuSeDemo software. In the shareqtcreatordfuse under the OpenMVIDE installation directory; click on the Choose in the middle (don’t click on the one on the left), select the bootloader.dfu file in the shareqtcreatorfirmwareOPENMV4 under the OpenMVIDE installation directory, then click Upgrade, select Yes in the pop-up window, and start burning the boot program , wait for the burning to be completed, and Upgrade successful is displayed below, indicating that the burning is successful.    Next, disconnect the data cable from the computer and remove the short-circuit cap; open OpenMVIDE, click on the connection in the lower left corner, it will prompt that OpenMV is not found, click OK; whether any OpenMV has become bricked, Yes; select the motherboard type as OpenMV Cam H7 (STM32H743) , click OK; erase the internal file system, Yes; prompt to disconnect OpenMV and reconnect it. At this time, connect the data cable to the computer, OpenMVIDE will start programming the board, wait for the programming to be completed, and will run the self-test after the prompt is successful. This Do not cut off the power first and wait for the self-test to be completed. When the blue light flashes, the self-test is completed. After completion, disconnect and reconnect, click the connection in the lower left corner, and three prompt boxes will appear in succession. This is because the self-made one does not have a Key, so it does not affect the use. Just click cancel. The burning is now complete and you can try running the example program.

    If you have any problems with production, please comment or send a private message and I will try my best to help solve it.

    The sample pictures and finished product pictures below are from the previous version. The open source version has been slightly modified based on it. Based on the current version, there will be no big difference. Recommended black board to prevent light leakage. (It is soldered with a soldering iron, there is no washing water, and my photography skills are not good, so let’s just take a look at it...)

    Empty board front and back

Finished product front and back