Timer 1 channel 1 on PA8
Select PA8 with the default TIM1_CH1 assignment. Check the chosen pin mapping before enabling the channel.
Blue Pill polyphonic tone generator pinout
A four-voice tone generator on STM32F103 uses independent timer channels for the outputs and SysTick for note timing.
STM32F103C8T6 Blue Pill
49 contacts Current packageSTM32F103C8T6 Blue Pill pinout
Header 1
Header 2
SWD header
USB connector
H3-1 · 3V3
Connects to 3V3. Use the specified board power connection.
All 49 pins
| Pin | Signal | Direction | Function |
|---|---|---|---|
| H1-1 | VB Power | Power | Connects to VBAT. Use the specified board power connection. |
| H1-2 | C13 Configurable I/O | Configurable I/O | Routes to MCU PC13. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H1-3 | C14 Configurable I/O | Configurable I/O | Routes to MCU PC14. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H1-4 | C15 Configurable I/O | Configurable I/O | Routes to MCU PC15. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H1-5 | A0 Configurable I/O | Configurable I/O | Routes to MCU PA0. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H1-6 | A1 Configurable I/O | Configurable I/O | Routes to MCU PA1. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H1-7 | A2 Configurable I/O | Configurable I/O | Routes to MCU PA2. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H1-8 | A3 Configurable I/O | Configurable I/O | Routes to MCU PA3. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H1-9 | A4 Configurable I/O | Configurable I/O | Routes to MCU PA4. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H1-10 | A5 Configurable I/O | Configurable I/O | Routes to MCU PA5. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H1-11 | A6 Configurable I/O | Configurable I/O | Routes to MCU PA6. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H1-12 | A7 Configurable I/O | Configurable I/O | Routes to MCU PA7. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H1-13 | B0 Configurable I/O | Configurable I/O | Routes to MCU PB0. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H1-14 | B1 Configurable I/O | Configurable I/O | Routes to MCU PB1. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H1-15 | B10 Configurable I/O | Configurable I/O | Routes to MCU PB10. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H1-16 | B11 Configurable I/O | Configurable I/O | Routes to MCU PB11. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H1-17 | R Active-low reset | Active-low reset | Connects to MCU NRST. Use a compatible open-drain reset signal. |
| H1-18 | 3.3 Power | Power | Connects to 3V3. Use the specified board power connection. |
| H1-19 | G Return | Return | Connects to the board’s ground plane. |
| H1-20 | G Return | Return | Connects to the board’s ground plane. |
| H2-1 | 3.3 Power | Power | Connects to 3V3. Use the specified board power connection. |
| H2-2 | G Return | Return | Connects to the board’s ground plane. |
| H2-3 | 5V Power | Power | Connects to 5V. Use the specified board power connection. |
| H2-4 | B9 Configurable I/O | Configurable I/O | Routes to MCU PB9. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H2-5 | B8 Configurable I/O | Configurable I/O | Routes to MCU PB8. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H2-6 | B7 Configurable I/O | Configurable I/O | Routes to MCU PB7. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H2-7 | B6 Configurable I/O | Configurable I/O | Routes to MCU PB6. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H2-8 | B5 Configurable I/O | Configurable I/O | Routes to MCU PB5. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H2-9 | B4 Configurable I/O | Configurable I/O | Routes to MCU PB4. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H2-10 | B3 Configurable I/O | Configurable I/O | Routes to MCU PB3. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H2-11 | A15 Configurable I/O | Configurable I/O | Routes to MCU PA15. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H2-12 | A12 Configurable I/O | Configurable I/O | Routes to MCU PA12. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H2-13 | A11 Configurable I/O | Configurable I/O | Routes to MCU PA11. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H2-14 | A10 Configurable I/O | Configurable I/O | Routes to MCU PA10. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H2-15 | A9 Configurable I/O | Configurable I/O | Routes to MCU PA9. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H2-16 | A8 Configurable I/O | Configurable I/O | Routes to MCU PA8. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H2-17 | B15 Configurable I/O | Configurable I/O | Routes to MCU PB15. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H2-18 | B14 Configurable I/O | Configurable I/O | Routes to MCU PB14. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H2-19 | B13 Configurable I/O | Configurable I/O | Routes to MCU PB13. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H2-20 | B12 Configurable I/O | Configurable I/O | Routes to MCU PB12. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H3-1 | 3V3 Power | Power | Connects to 3V3. Use the specified board power connection. |
| H3-2 | DIO Configurable I/O | Configurable I/O | Routes to MCU PA13. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H3-3 | CLK Configurable I/O | Configurable I/O | Routes to MCU PA14. Choose the applicable GPIO or peripheral function in the MCU documentation. |
| H3-4 | GND Return | Return | Connects to the board’s ground plane. |
| H4-1 | VBUS Power | Power | Connects to 5V. Use the specified board power connection. |
| H4-2 | D- Bidirectional | Bidirectional | USB data line. PCB net destination is PA11. |
| H4-3 | D+ Bidirectional | Bidirectional | USB data line. PCB net destination is PA12. |
| H4-4 | ID Unconfirmed | Unconfirmed | The board source supplies no net for this position. Consult the schematic before use. |
| H4-5 | GND Return | Return | Connects to the board’s ground plane. |
Signal assignments
Electrical limits
| Parameter | Limit | Conditions and source |
|---|---|---|
| Logic swing0–3.3 V nominal | 0–3.3 V nominal | Probe with a high-impedance instrument before connecting an audio input. Blue Pill board schematic |
| Voice count4 | 4 | One voice per timer in the original firmware. Check for timer conflicts with PWM or other libraries. STM32-TimerTone project |
Models and documents
The bench circuit measures one configured voice on PA8 (TIM1_CH1). The original project allows you to choose a channel on each timer. For acoustic output use a high-impedance amplifier input or an appropriate driver.
- 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.
- Original Spark Logic project discussion· Author’s hardware, firmware and bench notes.
- STMicroelectronics RM0008 reference manual· Timer modes, DMA request mapping and USB registers.
- STM32-TimerTone source· Original four-voice timer library and TonePlayer example.
- STM32-base · STM32F103C8T6 Blue Pill· Board identification, connector numbering and documented net destinations.
- STMicroelectronics MCU datasheet· MCU electrical specifications and package pin functions.
- STM32F103C8T6 Blue Pill schematic· PCB power, debug, connector and peripheral wiring.