STM8S003F3P6TR from STMicroelectronics, in a TSSOP-20. Pinout and pin descriptions extracted from the manufacturer datasheet by ds2sf; symbol, footprint, and 3D from KiCad-official CAD.

Pinout

Pin	Name	Type	Function
1	PD4/BEEP/TIM2_CH1/UART1_CK	bidirectional	Port D bit 4. General-purpose high-sink I/O; default alt functions: BEEP output, TIM2 channel 1, or UART1 synchronous clock. 5 V tolerant, floating input at reset.
2	PD5/AIN5/UART1_TX	bidirectional	Port D bit 5. High-sink digital I/O, ADC analog input 5, or UART1 transmit data. Floating input at reset.
3	PD6/AIN6/UART1_RX	bidirectional	Port D bit 6. High-sink digital I/O, ADC analog input 6, or UART1 receive data. Floating input at reset.
4	NRST	bidirectional	Active-low bidirectional reset pin. Internal weak pull-up; asserted low resets the MCU and drives low during internal reset.
5	PA1/OSCIN	bidirectional	Port A bit 1 or external crystal/resonator input (OSCIN) for the HSE oscillator. In halt/active-halt mode PA1 is forced to weak pull-up input; use PA1 only as input if these modes are used.
6	PA2/OSCOUT	bidirectional	Port A bit 2 or external crystal/resonator output (OSCOUT) for the HSE oscillator. Standard-speed digital I/O (not high-sink).
7	VSS	power_in	Digital ground reference (0 V) for the MCU core and I/O.
8	VCAP	passive	Internal 1.8 V core-regulator decoupling capacitor pin. Requires an external ceramic capacitor to VSS (typ. 1 µF) per section 9.3.1; not to be driven externally.
9	VDD	power_in	Main digital power supply. Operating range 2.95 V to 5.5 V; decouple with a local ceramic capacitor to VSS.
10	PA3/TIM2_CH3/[SPI_NSS]	bidirectional	Port A bit 3. High-sink GPIO; default alt function TIM2 channel 3. When option bit AFR1 is set, SPI master/slave select (SPI_NSS) is remapped onto this pin.
11	PB5/I2C_SDA/[TIM1_BKIN]	bidirectional	Port B bit 5, default alt function I2C serial data (SDA). True open-drain output (no P-channel or protection diode to VDD); external pull-up required. AFR4 remaps TIM1_BKIN onto this pin.
12	PB4/I2C_SCL/[ADC_ETR]	bidirectional	Port B bit 4, default alt function I2C serial clock (SCL). True open-drain output (no P-channel/protection diode to VDD); external pull-up required. AFR4 remaps ADC external trigger (ADC_ETR) onto this pin.
13	PC3/TIM1_CH3/[TLI]/[TIM1_CH1N]	bidirectional	Port C bit 3 (high-sink). Default alt function TIM1 channel 3. AFR3 remaps this pin to the top-level interrupt (TLI); AFR7 remaps to TIM1 inverted channel 1 (TIM1_CH1N).
14	PC4/CLK_CCO/TIM1_CH4/AIN2/[TIM1_CH2N]	bidirectional	Port C bit 4 (high-sink). Default alt functions: configurable clock output (CCO), TIM1 channel 4, or ADC analog input 2. AFR7 remaps to TIM1 inverted channel 2 (TIM1_CH2N).
15	PC5/SPI_SCK/[TIM2_CH1]	bidirectional	Port C bit 5 (high-sink). Default alt function SPI serial clock (SCK). AFR0 remaps to TIM2 channel 1.
16	PC6/SPI_MOSI/[TIM1_CH1]	bidirectional	Port C bit 6 (high-sink). Default alt function SPI master-out/slave-in (MOSI). AFR0 remaps to TIM1 channel 1.
17	PC7/SPI_MISO/[TIM1_CH2]	bidirectional	Port C bit 7 (high-sink). Default alt function SPI master-in/slave-out (MISO). AFR0 remaps to TIM1 channel 2.
18	PD1/SWIM	bidirectional	Port D bit 1, default alt function Single-Wire Interface Module (SWIM) for programming and debug. In weak pull-up input during and after reset; fast (O4) push-pull output when driven.
19	PD2/AIN3/[TIM2_CH3]	bidirectional	Port D bit 2 (high-sink). Default alt function ADC analog input 3. AFR1 remaps TIM2 channel 3 onto this pin.
20	PD3/AIN4/TIM2_CH2/ADC_ETR	bidirectional	Port D bit 3 (high-sink). Default alt functions: ADC analog input 4, TIM2 channel 2, or ADC external trigger (ADC_ETR).

Key specifications

Parameter	Value
Manufacturer	STMicroelectronics
Package	TSSOP-20
Category	MCU
Pins	20

Ordering variants

Same part, different packaging or reel option.

STM8S003F3P6TR
STM8S003F3P6TRU6
STM8S003F3P6TRU6TR
STM8S003F3P6TRT6
STM8S003F3P6TRT6TR

CAD (KiCad official)

Symbol: STM8S003F3P6TR
Footprint: Package_SO:TSSOP-20_4.4x6.5mm_P0.65mm
3D model: TSSOP-20 (KiCad packages3D, STEP)

3D model downloads

Two STEP files. Same geometry, different body top:

File	Size	Use it when
`stm8s003f3p6tr.step`	267 KB	You want the bare part, or you mark your own boards.
`stm8s003f3p6tr-etched.step`	3.9 MB	You want the part with `STM8S003F3P6TR` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 936 faces against 327 in the bare model. It survives export, section views, and rendering in any CAD tool, and it drops straight into KiCad or Fusion with no extra setup.

Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

Datasheet: STMicroelectronics datasheet (104 pp, sha256 f22af8c2e2680b97, retrieved 2026-08-17, tier: manufacturer)
Extractor: ds2sf (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.
CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF