STM32F411RET6 system board - plug-in expansion board

【Foreword】

I have been learning STM32 recently and want to make an STM32 system board that can be used to debug programs. In order to add peripherals, I have designed an expansion board that can be plugged directly into the system board. The design of the expansion board can be changed according to different debugging equipment, and the system board does not need to be redesigned, which improves the utilization of the system board.

[System Board] System board schematic diagram:

STM32F411RET6 is used as the main control, and the peripheral circuits include 8M crystal oscillator and 32.678k crystal oscillator;

Button reset circuit;

Use a simple, low-cost resistor-capacitor reset.

Power supply circuit:

It can be powered by Type-C interface or external 5V power supply.

A fuse is added to prevent circuit damage.

The power supply switch is a self-locking switch, press it once to power on, and the power indicator light will light up.

Contains 5V to 3.3V circuit and filter circuit.

Contains BAT button battery 3.3V power supply, which can be used to make a real-time clock or use the backup area to store data.

External expansion pins:

Lead out all the remaining IO port pins in a double row of pin headers.

In order to facilitate debugging, the SWD debugging interface and USART1 serial port communication are introduced.

In addition, 5V and 3.3V power supply pins have been added, which can be used to power peripherals.

【expanding board】

Expansion board schematic diagram:

The expansion board uses a female header with extended pin headers to connect directly to the system board.

An eight-bit common anode digital tube is designed, using 8 IO ports to connect triodes, which occupies a lot of IO ports. When the number of IO ports is insufficient, the 74HC595 displacement buffer can be considered for design;

a passive buzzer;

Four LED indicators (high level drive);

Four buttons (pull-up);

OLED's 4-pin interface can be directly plugged into a 4-pin OLED.

Except for the pins used by these peripherals, the remaining pins are led out with long rows of pins to facilitate the connection of other peripherals.