Instrument Training Camp: Portable Oscilloscope and H750 Core Board Replica

This is a replica of the portable oscilloscope from the LCSC + Hardwood Classroom Instrumentation Training Camp.
This project consists of two 4-layer boards:
1. H750 core board (copied from: https://oshwhub.com/micespring/stm32h750vb-CoreBoard_copy). Many unnecessary circuits have been removed, component packages have been changed to 0603 for easier soldering, and the pin headers have been redesigned to match the Hardwood Classroom H750 core board for easier connection to the oscilloscope motherboard. The core board can also be used as a standalone development board.
2. Oscilloscope expansion board: The schematic is copied from the course's example project, the screen interface has been moved to the core board, and the power interface has been changed to Type-C. This
 
is my first attempt at designing a 4-layer board, so there are bound to be many shortcomings!
 
The project still has some issues; I can't consistently measure the waveform of DAC_OUT using this oscilloscope. I don't know why.
I specifically built a PWM board for testing, and the input waveform can be measured.
 
Photos of JLCPCB 4-layer PCB:
H750 core board:
Oscilloscope expansion board:
3D Monkey 3D printed shell photos:
 
 
LCPCB online store panel printing photos:
The panel was exported from a PDF using an editor, converted to an image, and then imported into the panel editor. It was then drawn according to the positions of each component, but the result was too small, so it's just usable. There may have been errors during various conversions and imports; I must pay attention to checking the dimensions next time!
 
Photos of the soldered PCB:
The soldering order for the H750 core board was: first solder the Type-C interface and power supply; after testing the power supply and confirming it was working, then solder the STM32 main unit and peripheral circuits; after testing it again, write the main program; the third step was to solder the LED screen circuit, then test if the screen lit up; after it lit up, solder the other peripheral circuits and pin headers! The test passed completely!
The expansion board also started with soldering the power supply circuit; after testing and confirming it was working, soldered the other components!
 
Here's a pitfall to note regarding the expansion board's power supply section: the FB pin feedback circuit of the MT3608 must be correctly connected; otherwise, it will burn out the MT3608 chip upon power-on testing, causing a short circuit in the entire power supply circuit! I initially bought only one 3608 diode, then bought ten more. After using half of them and repeatedly disassembling and testing the peripheral components, I finally found the cause: I don't know if the D6 transient suppression diode from the original official project was faulty, or if the component I bought was faulty. This diode wasn't labeled with positive and negative terminals, and I might have connected it backwards, causing the feedback circuit to fail and burning out the chip!
Later, I tested D4 and D5, and the circuit using the same diode at -12V also didn't work properly. I replaced D4, D5, and D6 with SS34 diodes, and the circuit worked normally!
 
Regarding the core board, I initially didn't notice and bought a common cathode RGB LED from the 3528. After replacing it with a common anode LED, it lit up normally! Please be careful not to make the same mistake!
 
Assembly test photos:
 
Program writing:
There's not much to say about the program part. I used the original official program, installing KeilMDKARM5.35 and STM32H750 from the pack provided in the group file, version 2.7.0.
Because the official H750 pin header connectors PB8 and PB9 were incorrectly labeled, I didn't notice this when designing the core board, so these two pins were reversed. I modified the pin definitions during compilation, and it compiled successfully!
The modified relay.h file is shown in the image.
Since this H750 core board includes a USB interface, flashing the program was relatively simple. Open the STM32CubeProgrammer software, connect the core board to the computer using a Type-C data cable, press and hold the Boot button to power on the core board, adjust the USB connection in STM32CubeProgrammer, and then open the compiled DAC.hex file to download and flash the program.