Spark Logic

STM32F103 PWM audio player with DMA connection guide

STM32F103 PWM audio player with DMA STM32F103C8T6 Blue Pill wiring guide with power, signal assignments, and bench checks.

STM32F103C8T6 Blue Pill

49 contacts Current package

Spark Logic project archive · The documented blue PCB has two 20-contact headers, SWD and Micro USB. Its PC13 user LED is active low. The USB D+ pull-up varies across production boards.

Power the board from USB

Required

Use a single USB cable to power the board through its native connector. Leave external power headers disconnected. Check the 3.3 V rail before attaching the debug probe.

Bench checks

  • Identify the USB power input and ground in the board schematic.
  • Measure roughly 3.3 V between the board logic rail and ground. Check for a short or wrong connector if the rail is low.

STM32F103C8T6 Blue Pill connector map

Connection scenarios

Check the PB6 PWM waveform

Run the playback test with a high-impedance probe attached to PB6 and a common ground. Use a buffer and filter designed for the load before connecting an audio transducer.

Bench checks

  • Start with fixed low, mid and high samples to verify duty cycle and timer preload.
  • Use a short ramp to verify that duty cycle changes at the expected sample cadence. Confirm DMA transfer completion and the chosen idle state.

Original PWM audio project and RM0008 Rev 21, DMA request mapping.

STM32F103C8T6 Blue Pill wiring map

Highlighted contacts are used in the required step or selected circuit. Select a contact to inspect it.

Header 1
Use the board connector marking and locate contact 1 before wiring.
Header 2
Use the board connector marking and locate contact 1 before wiring.
SWD header
Use the board connector marking and locate contact 1 before wiring.
USB connector
Use the board connector marking and locate contact 1 before wiring.
Selected pin details

H1-12 · A7

Configurable I/O · GPIO

Routes to MCU PA7. Choose the applicable GPIO or peripheral function in the MCU documentation.

STM32F103C8T6 Blue Pill connector map

Electrical limits · Pin in the reference

Models and documents

This guide follows the archived Blue Pill example using a short unsigned 8-bit, 16 kHz sample array in Flash. The output is first checked as a logic waveform.

STM32F103C8T6 Blue Pill
The documented blue PCB has two 20-contact headers, SWD and Micro USB. Its PC13 user LED is active low. The USB D+ pull-up varies across production boards.