The world's bitter stars have been around for a long time, and I designed a piece of Openmv4-H7 based on the github information and my daily usage habits.

1. Open source information

2. Schematic design

• 2.1 Power supply part

For this power supply, we use the extremely advanced TYPE-C power supply method, so you don’t have to worry about the pros and cons. Add magnetic beads to filter out high-frequency noise and spikes on power lines. The two diodes are protected against reverse connection. It is recommended to use a Schottky diode because Schottky has a lower forward voltage drop than ordinary diodes. When purchasing a Schottky diode, pay attention to the reverse withstand voltage and forward voltage drop . These parameters are the average rectified current . For LDO we choose BL117-3.3 and BL9193-18BAPRN . BL1117-3.3 is responsible for stepping down 5V to 3.3V to power camera peripherals, MCU, LED, etc. The BL9193-18BAPRN is responsible for converting 3.3V to 1.8V to power the internal sensor of OV7725.

• 2.2 Peripheral part

We chose Meihua's RGB three-color LED for the RGB light , and the ports correspond to LED 1.2.3 in the openmv ide. For infrared, I chose IR23-51C in 1206 package and used BSS138 NMOS driver, which corresponds to LED 4 in the software. This time I chose to place the SD card on the reverse side and chose a TF card holder with self-ejection .

• 2.3 Sensor

  This time we chose the OV7725 sensor with 30W pixels . The price on Taobao without FIFO is about 30 yuan. According to the camera drawing provided by the store, we can see that the OV772510 pin DVDD is powered by 1.8V voltage .

• 2.4 MCU

We choose STM32H750VBT6 for MCU. Here are the configurations of the two chips (750 on the left and 743 on the right). You can see that the internal FLASH of 750 is smaller than that of 743. We solve this problem through a TF card. The 750 has three 16-bit ADCs, while the 743 only has three 14-bit ADCs. And the 750 has a lower price and higher cost performance than the 743. Note: Do not change the values ​​of the two capacitors next to the 12MHZ crystal oscillator at will, as it may cause the crystal oscillator to not vibrate. During layout, the crystal oscillator should also be placed close to the MCU .

3.PCB

4.3D preview