pillScope Plus: STM32F401 Black Pill educational oscilloscope

Parts Needed

• STM32F401CC Black Pill
• 128x160 ST7735 TFT display
• 3 pushbuttons
• LM358 dual op-amp (a rail-to-rail part is better)
• 2x 68kΩ and 2x 500kΩ resistors (offset and attenuator)
• 5V power supply
• Optional: opto-isolated USB-UART adapter, BNC connector
• ST-Link or USB DFU for flashing

Steps

1. 1

   Build the front end

   Following the schematic, wire the op-amp input stage. The 68k resistors set a 1.65V virtual ground and the 500k resistors attenuate the input. The output goes to PA0 (ADC1_IN0).

2. 2

   Connect the display and buttons

   Connect the ST7735 to SPI1: SCK on PB3, MOSI on PB5, CS on PB12, RST on PB13 and DC on PB14. The buttons go on PB9 (Up), PB8 (Select) and PB7 (Down).

3. 3

   Build and flash

   Compile with make (the source is in Core/Src) and flash the binary with an ST-Link or the Black Pill's USB DFU bootloader.

4. 4

   Calibrate and measure

   Run the auto-calibration from the UI before use. Because of the virtual ground, the scope and the circuit under test must not share a ground. Use an isolated supply or the opto-isolated UART adapter.

5. 5

   Save captures

   Send 's' over UART for CSV output (TekScope-compatible), or 'S' for raw data that the companion app streams to TekScope in near real time.