Relay module with WeAct Black Pill STM32F411CE

Wiring for the Relay module 1 channel (5 V) on the WeAct Black Pill STM32F411CE (STM32F411CE, 3.3 V logic), chosen with the same pin rules BoardPilot uses: default buses first, and no pins that are used for flash, USB, the debugger or booting.

Wiring

Relay module pin	Role	WeAct Black Pill STM32F411CE pin	Notes
IN	Input to the part	B12 (PB12)	Many modules switch on with IN LOW. Some do not react to 3.3 V: check with a test
GND	Ground	G
VCC	Power	5V	Needs 5 V for the coil: use 5V
COM	Not wired to the board	not connected	Relay common contact. Mains voltage is dangerous
NO	Not wired to the board	not connected	Normally open contact
NC	Not wired to the board	not connected	Normally closed contact

Check before you power it on

Supply: 5 V from the 5V pin.
Motors, servos, relays and LED strips can draw more current than the WeAct Black Pill STM32F411CE’s pins or USB can give. Power them separately and connect the grounds together.

Test code (Arduino)

void setup() {
  pinMode(PB12, OUTPUT);  // IN on B12
}

void loop() {
  digitalWrite(PB12, HIGH);
  delay(500);
  digitalWrite(PB12, LOW);
  delay(500);
}

Arduino board: STMicroelectronics:stm32:GenF4:pnum=BLACKPILL_F411CE,usb=CDCgen,upload_method=dfuMethod. To upload over USB, hold BOOT0, press and release NRST, then release BOOT0 (DFU mode). An ST-LINK on the SWD pins also works.

Questions

Which WeAct Black Pill STM32F411CE pins do I use for the Relay module?

IN → B12 (PB12), GND → G, VCC → 5V.

Does the Relay module work with the WeAct Black Pill STM32F411CE at 3.3 V?

Yes: the Relay module runs at 5 V and the WeAct Black Pill STM32F411CE uses 3.3 V signals, so no level shifting is needed.

BoardPilot checks this wiring in 3D as you build it, and finds crossed or missing wires on the real board.

Download BoardPilot

Full WeAct Black Pill STM32F411CE pinout · Relay module 1 channel (5 V): all pins and data

The Relay module on other boards

ESP32 DevKit Arduino Mega 2560 R3 Arduino Nano Arduino Uno R3 ESP32-C3-DevKitM-1 ESP32-S3-DevKitC-1 Nordic nRF52840 DK NUCLEO-F401RE Raspberry Pi Pico 2 Raspberry Pi Pico W Raspberry Pi Pico Teensy 4.1

Other parts on the WeAct Black Pill STM32F411CE

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