# SMD V1 ## Description Compact Low-Power Wrist Altimeter (STM32G070 + BMP580 + 1.77" SPI TFT) – Completed 30 × 20 mm, 2-Layer, 1.6 mm FR-4 PCB Layout Ready for Pre-Manufacturing Review ## Project Details - **Owner:** smd123 - **Created:** 12/17/2025 - **Last Updated:** 12/17/2025 - **Visibility:** Public - **Net Type:** BAT = Power - **Net Type:** USB_DP = High Speed - **Net Type:** VBUS = Power - **Net Type:** SWD = Medium Speed - **Domain:** Consumer Electronics - **Net Type:** I2C = Medium Speed - **Net Type:** GND = Ground - **Human Interface:** Buttons,Display - **Net Type:** SPI = Medium Speed - **Connectivity:** USB - **Manufacturing Quantity Target:** 50 - **Net Type:** Backlight_PWM = Medium Speed - **Board Height:** 20mm - **Net Type:** 3V3 = Power - **Net Type:** USB_DN = High Speed - **System Architecture:** STM32G070-based wrist altimeter; 2-layer, 1.6 mm FR-4 PCB with all components on top side, solid bottom GND reference plane; single 3V3 domain from LP38693 LDO, USB-powered via TP4056 Li-ion charger with BAT rail distribution; SPI for TFT, I2C for BMP581, USB D+/D- ESD-protected only (no data interface), PWM-controlled backlight NMOS referenced to BAT, SWD and power brought out to test pads. - **Operating Voltage:** 3.3V - **Software:** Bare metal - **Power Requirements:** USB - **Board Width:** 30mm ## Key Components ### J1 — [124018312112A](https://www.flux.ai/adrian95/124018312112a~dea.md) - Manufacturer Name: Amphenol - Role Details: USB-C receptacle for charging input - Role: Connector - Datasheet URL: https://cdn.amphenol-cs.com/media/wysiwyg/files/documentation/datasheet/inputoutput/io_waterproof_usb_type_c.pdf - Part Type: USB C - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Part Number: 124018312112A - Connector Type: USB Connectors **Pins:** - CC1 [pin A5] - CC2 [pin B5] - D1- [pin A7] - D1+ [pin A6] - D2- [pin B7] - D2+ [pin B6] - GND_A [pin A1] - GND_A [pin A12] - GND_B [pin B1] - GND_B [pin B12] - RX1- [pin B10] - RX1+ [pin B11] - RX2- [pin A10] - RX2+ [pin A11] - SBU1 [pin A8] - SBU2 [pin B8] - SHIELD [pin SH2] - SHIELD [pin SH4] - SHIELD [pin SH1] - SHIELD [pin SH3] - TX1- [pin A3] - TX1+ [pin A2] - TX2- [pin B3] - TX2+ [pin B2] - VBUS_A [pin A4] - VBUS_A [pin A9] - VBUS_B [pin B4] - VBUS_B [pin B9] ### Q1 — [BSS138-G](https://www.flux.ai/lcsc/bss138-g~s3zl.md) - Manufacturer Part Number: BSS138-G - Package or Case Code: SOT-23-3_L2.9-W1.3-P1.90-LS2.4-BR - JLCPCB Part Class: Extended Part - Role Details: Backlight PWM control NMOS transistor - LCSC Part Number: C890264 - Package: SOT-23-3_L2.9-W1.3-P1.90-LS2.4-BR - Manufacturer Name: onsemi(安森美) - Role: Switching **Pins:** - D [pin 3] - G [pin 1] - S [pin 2] ### SW1 — [SKRKAEE020](https://www.flux.ai/lcsc/skrkaee020~g9gr.md) - Voltage Rating: 12V - Role: Debouncing - Role Details: Tactile switch for user input (MCU EXTI) - Part Type: Switch - Datasheet URL: https://storage.googleapis.com/graviton-electric-symbols/document_assets/lcsc/1809201020_ALPSALPINE-SKRKAEE020_C115357.pdf - Switch Type: Tactile Switch (Momentary) - Manufacturer Part Number: SKRKAEE020 - Manufacturer Name: Alps Alpine - JLCPCB Part Class: Extended Part - Throw Configuration: SPST - LCSC Part Number: C115357 - Current Rating: 50mA - Product Info Url: https://lcsc.com/product-detail/Tactile-Switches_ALPS_SKRKAEE020_3-4-2-1-57N_C115357.html - Package or Case Code: SW-SMD_L3.9-W3.0-P4.45 **Pins:** - 1 [pin 1] - 2 [pin 2] ### U1 — [STM32G070CBT6TR](https://www.flux.ai/adrian95/stm32g070cbt6tr~yo4.md) - Part Type: Microcontroller - Manufacturer Name: STMicroelectronics - Datasheet URL: https://www.st.com/resource/en/datasheet/stm32g070cb.pdf - Manufacturer Part Number: STM32G070CBT6TR - Role Details: 32-bit ARM Cortex-M0+ microcontroller, 64 MHz - Role: Main MCU - License: https://creativecommons.org/licenses/by/4.0/ **Pins:** - NRST [pin 10] - PA0/SPI2_SCK/USART2_CTS/USART4_TX/ADC_IN0/TAMP_IN2/WKUP1 [pin 11] - PA1/SPI1_SCK/I2S1_CK/USART2_RTS_DE_CK/USART4_RX/TIM15_CH1N/I2C1_SMBA/EVENTOUT/ADC_IN1 [pin 12] - PA10/SPI2_MOSI/USART1_RX/TIM1_CH3/TIM17_BKIN/I2C1_SDA/EVENTOUT [pin 32] - PA11/SPI1_MISO/I2S1_MCK/USART1_CTS/TIM1_CH4/TIM1_BKIN2/I2C2_SCL [pin 33] - PA12/SPI1_MOSI/I2S1_SD/USART1_RTS_DE_CK/TIM1_ETR/I2S_CKIN/I2C2_SDA [pin 34] - PA13/SWDIO/IR_OUT/EVENTOUT [pin 35] - PA14/SWCLK/USART2_TX/EVENTOUT/BOOT0 [pin 36] - PA15/SPI1_NSS/I2S1_WS/USART2_RX/USART4_RTS_DE_CK/USART3_RTS_DE_CK/EVENTOUT [pin 37] - PA2/SPI1_MOSI/I2S1_SD/USART2_TX/TIM15_CH1/ADC_IN2/WKUP4/LSCO [pin 13] - PA3/SPI2_MISO/USART2_RX/TIM15_CH2/EVENTOUT/ADC_IN3 [pin 14] - PA4/SPI1_NSS/I2S1_WS/SPI2_MOSI/TIM14_CH1/EVENTOUT/ADC_IN4/RTC_OUT2 [pin 15] - PA5/SPI1_SCK/I2S1_CK/USART3_TX/EVENTOUT/ADC_IN5 [pin 16] - PA6/SPI1_MISO/I2S1_MCK/TIM3_CH1/TIM1_BKIN/USART3_CTS/TIM16_CH1/ADC_IN6 [pin 17] - PA7/SPI1_MOSI/I2S1_SD/TIM3_CH2/TIM1_CH1N/TIM14_CH1/TIM17_CH1/ADC_IN7 [pin 18] - PA8/MCO/SPI2_NSS/TIM1_CH1/EVENTOUT [pin 28] - PA9/MCO/USART1_TX/TIM1_CH2/SPI2_MISO/TIM15_BKIN/I2C1_SCL/EVENTOUT [pin 29] - PB0/SPI1_NSS/I2S1_WS/TIM3_CH3/TIM1_CH2N/USART3_RX/ADC_IN8 [pin 19] - PB1/TIM14_CH1/TIM3_CH4/TIM1_CH3N/USART3_RTS_DE_CK/EVENTOUT/ADC_IN9 [pin 20] - PB10/USART3_TX/SPI2_SCK/I2C2_SCL/ADC_IN11 [pin 22] - PB11/SPI2_MOSI/USART3_RX/I2C2_SDA/ADC_IN15 [pin 23] - PB12/SPI2_NSS/TIM1_BKIN/TIM15_BKIN/EVENTOUT/ADC_IN16 [pin 24] - PB13/SPI2_SCK/TIM1_CH1N/USART3_CTS/TIM15_CH1N/I2C2_SCL/EVENTOUT [pin 25] - PB14/SPI2_MISO/TIM1_CH2N/USART3_RTS_DE_CK/TIM15_CH1/I2C2_SDA/EVENTOUT [pin 26] - PB15/SPI2_MOSI/TIM1_CH3N/TIM15_CH1N/TIM15_CH2/EVENTOUT/RTC_REFIN [pin 27] - PB2/SPI2_MISO/USART3_TX/EVENTOUT/ADC_IN10 [pin 21] - PB3/SPI1_SCK/I2S1_CK/TIM1_CH2/USART1_RTS_DE_CK/EVENTOUT [pin 42] - PB4/SPI1_MISO/I2S1_MCK/TIM3_CH1/USART1_CTS/TIM17_BKIN/EVENTOUT [pin 43] - PB5/SPI1_MOSI/I2S1_SD/TIM3_CH2/TIM16_BKIN/I2C1_SMBA/WKUP6 [pin 44] - PB6/USART1_TX/TIM1_CH3/TIM16_CH1N/SPI2_MISO/I2C1_SCL/EVENTOUT [pin 45] - PB7/USART1_RX/SPI2_MOSI/TIM17_CH1N/USART4_CTS/I2C1_SDA/EVENTOUT [pin 46] - PB8/SPI2_SCK/TIM16_CH1/USART3_TX/TIM15_BKIN/I2C1_SCL/EVENTOUT [pin 47] - PB9/IR_OUT/TIM17_CH1/USART3_RX/SPI2_NSS/I2C1_SDA/EVENTOUT [pin 48] - PC13/TIM1_BKIN/TAMP_IN1/RTC_TS/RTC_OUT1/WKUP2 [pin 1] - PC14/TIM1_BKIN2/OSC32_IN [pin 2] - PC15/OSC32_EN/OSC_EN/TIM15_BKIN/OSC32_OUT [pin 3] - PC6/TIM3_CH1 [pin 30] - PC7/TIM3_CH2 [pin 31] - PD0/EVENTOUT/SPI2_NSS/TIM16_CH1 [pin 38] - PD1/EVENTOUT/SPI2_SCK/TIM17_CH1 [pin 39] - PD2/USART3_RTS_DE_CK/TIM3_ETR/TIM1_CH1N [pin 40] - PD3/USART2_CTS/SPI2_MISO/TIM1_CH2N [pin 41] - PF0-OSC_IN/TIM14_CH1/OSC_IN [pin 8] - PF1-OSC_OUT/OSC_EN/TIM15_CH1N/OSC_OUT [pin 9] - VBAT [pin 4] - VDD/VDDA [pin 6] - VREF+ [pin 5] - VSS/VSSA [pin 7] ### U2 — [BMP581](https://www.flux.ai/jecstronic/bmp581~7m6.md) - Role: Sensor - Manufacturer Part Number: BMP581 - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Name: Bosch Sensortec - Part Type: Sensor - Datasheet URL: https://www.bosch-sensortec.com/media/boschsensortec/downloads/datasheets/bst-bmp581-ds004.pdf - Role Details: Barometric pressure sensor, I2C interface **Pins:** - CSB [pin 6] - INT [pin 7] - SCK [pin 2] - SDI [pin 4] - SDO [pin 5] - VDD [pin 10] - VDDIO [pin 1] - VSS [pin 3] - VSS [pin 9] - VSS [pin 8] ### U3 — [N177-1216TCWPG01-H14](https://www.flux.ai/gfelipesanchezs/n177-1216tcwpg01-h14~4d.md) - Part Type: Display Device - Manufacturer Part Number: N177-1216TCWPG01-H14 - Role Details: 1.77" SPI TFT display module with PWM backlight - Manufacturer Name: WiseChip - LCSC Part Number: C5123575 - Role: Display Device - JLCPCB Part Class: Extended Part - Datasheet URL: https://wmsc.lcsc.com/wmsc/upload/file/pdf/v2/lcsc/2208051800_Newvisio-N177-1216TCWPG01-H14_C5123575.pdf **Pins:** - A0 [pin 7] - CS [pin 12] - GND [pin 2] - GND [pin 5] - GND [pin 13] - IOVCC [pin 11] - LED-N [pin 3] - LED-P [pin 4] - NC [pin 14] - NC [pin 1] - RES [pin 6] - SCK [pin 9] - SDA [pin 8] - VCC [pin 10] ### U4 — [TP4056](https://www.flux.ai/vasy_skral/tp4056~xa.md) - Role: Power Management - Part Type: Integrated Circuit - Datasheet URL: https://dlnmh9ip6v2uc.cloudfront.net/datasheets/Prototyping/TP4056.pdf - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Part Number: TP4056 - Manufacturer Name: NanJing Top Power ASIC Corp. - Role Details: 1S Li-ion battery charger **Pins:** - ~CHRG [pin 7] - ~STDBY [pin 6] - BAT [pin 5] - CE [pin 8] - EP [pin 9] - GND [pin 3] - PROG [pin 2] - TEMP [pin 1] - VCC [pin 4] ### U5 — [LP38693MP-3.3/NOPB](https://www.flux.ai/adrian95/lp38693mp-33nopb~m4z.md) - Role Details: 3.3 V low-dropout regulator, 500 mA output - Datasheet URL: https://www.ti.com/lit/ds/symlink/lp38693-q1.pdf - Manufacturer Part Number: LP38693MP-3.3/NOPB - Part Type: Integrated Circuit - Role: Linear Regulator - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Name: Texas Instruments **Pins:** - EN [pin 1] - GND [pin 5] - IN [pin 4] - NC [pin 2] - OUT [pin 3] ### U6 — [USBLC6-2P6](https://www.flux.ai/kicad-part-library/usblc6-2p6~djt.md) - Manufacturer Part Number: USBLC6-2P6 - Datasheet URL: https://www.st.com/resource/en/datasheet/usblc6-2.pdf - Package or Case Code: SOT-666 - Role Details: ESD protection diode array for USB D+ / D- lines - Manufacturer Name: Texas Instruments Inc. - Role: Protection **Pins:** - GND [pin 2] - I/O1 [pin 6] - I/O1 [pin 1] - I/O2 [pin 3] - I/O2 [pin 4] - VBUS [pin 5] *The full schematic, PCB layout, bill of materials, and interactive design are available at [https://www.flux.ai/smd123/smd-v1~9j](https://www.flux.ai/smd123/smd-v1~9j).* --- *Generated from [https://www.flux.ai/smd123/smd-v1~9j](https://www.flux.ai/smd123/smd-v1~9j)*