# Solar Dashboard Compass ## Description Solar-powered dashboard compass with LiPo storage, QMC5883L magnetometer, STM32L031 controller, and three multiplexed red 7-segment displays. ## Project Details - **Owner:** brooks - **Created:** 6/9/2026 - **Last Updated:** 6/22/2026 - **Visibility:** Public - **Implementation Details:** MCP73871 solar/LiPo load-sharing charger, MCP1703A LDO, STM32L031 MCU, QMC5883L I2C magnetometer, multiplexed common-cathode displays - **Domain:** Automotive accessory / dashboard display - **Power Requirements:** Small 5–6 V solar panel input, single-cell LiPo storage, 3.3 V regulated electronics rail - **Operating Voltage:** 3.3V - **Human Interface:** Three red 7-segment digits showing magnetic heading in degrees ## Key Components ### DS1 — [HDSP-5503](https://www.flux.ai/adrian95/hdsp-5503~s80.md) - Role Details: Keep HDSP-5503 common-cathode display. JLC/LCSC alternatives found were not safe drop-in replacements; LCSC stock shown is low but enough for 3 units at check time. - Allow Substitutes: No - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Part Number: HDSP-5503 - Part Type: Display Module - Manufacturer Name: Broadcom Limited - Datasheet URL: https://www.mouser.com/datasheet/2/678/AV02_1107EN_2022_12_08-1827817.pdf **Pins:** - ANODE_A [pin 7] - ANODE_B [pin 6] - ANODE_C [pin 4] - ANODE_D [pin 2] - ANODE_DP [pin 5] - ANODE_E [pin 1] - ANODE_F [pin 9] - ANODE_G [pin 10] - COMMON_CATHODE_1 [pin 3] - COMMON_CATHODE_2 [pin 8] ### DS2 — [HDSP-5503](https://www.flux.ai/adrian95/hdsp-5503~s80.md) - Allow Substitutes: No - Manufacturer Part Number: HDSP-5503 - Datasheet URL: https://www.mouser.com/datasheet/2/678/AV02_1107EN_2022_12_08-1827817.pdf - Part Type: Display Module - Manufacturer Name: Broadcom Limited - Role Details: Keep HDSP-5503 common-cathode display. JLC/LCSC alternatives found were not safe drop-in replacements; LCSC stock shown is low but enough for 3 units at check time. - License: https://creativecommons.org/licenses/by/4.0/ **Pins:** - ANODE_A [pin 7] - ANODE_B [pin 6] - ANODE_C [pin 4] - ANODE_D [pin 2] - ANODE_DP [pin 5] - ANODE_E [pin 1] - ANODE_F [pin 9] - ANODE_G [pin 10] - COMMON_CATHODE_1 [pin 3] - COMMON_CATHODE_2 [pin 8] ### DS3 — [HDSP-5503](https://www.flux.ai/adrian95/hdsp-5503~s80.md) - Datasheet URL: https://www.mouser.com/datasheet/2/678/AV02_1107EN_2022_12_08-1827817.pdf - Allow Substitutes: No - Part Type: Display Module - Manufacturer Name: Broadcom Limited - Role Details: Keep HDSP-5503 common-cathode display. JLC/LCSC alternatives found were not safe drop-in replacements; LCSC stock shown is low but enough for 3 units at check time. - Manufacturer Part Number: HDSP-5503 - License: https://creativecommons.org/licenses/by/4.0/ **Pins:** - ANODE_A [pin 7] - ANODE_B [pin 6] - ANODE_C [pin 4] - ANODE_D [pin 2] - ANODE_DP [pin 5] - ANODE_E [pin 1] - ANODE_F [pin 9] - ANODE_G [pin 10] - COMMON_CATHODE_1 [pin 3] - COMMON_CATHODE_2 [pin 8] ### J1 — [691213510002](https://www.flux.ai/adrian95/691213510002~nop.md) - Manufacturer Name: Kefa - Datasheet URL: https://www.we-online.com/katalog/datasheet/6912135100xx.pdf - JLCPCB Part Class: Extended Part - LCSC Part Number: C474952 - Manufacturer Part Number: KF128-5.08-2P-AA - Part Type: Connector - Role Details: Solar panel input connector substituted to LCSC/JLCPCB-stocked 2-position 5.08 mm through-hole terminal block for back-mounted solar panel leads. **Pins:** - P1 [pin 2] - P2 [pin 1] ### J2 — [B2B-PH-K-S](https://www.flux.ai/adrian95/b2b-ph-k-s~fx.md) - Part Type: Connector - Datasheet URL: https://www.jst-mfg.com/product/pdf/eng/ePH.pdf - LCSC Part Number: C131337 - Manufacturer Part Number: B2B-PH-K-S(LF)(SN) - JLCPCB Part Class: Extended Part - License: https://creativecommons.org/licenses/by/4.0/ - Package or Case Code: JST_B2B-PH-K-S - Manufacturer Name: JST - Role Details: 2-pin JST PH vertical LiPo connector updated to LCSC/JLCPCB-stocked active variant; intended for short leads from back-mounted LiPo pack. **Pins:** - 1 [pin 1] - 2 [pin 2] ### Q1 — [MMBT2222ALT3G](https://www.flux.ai/adrian95/mmbt2222alt3g~vum.md) - Datasheet URL: https://www.onsemi.com/pdf/datasheet/mmbt2222lt1-d.pdf - Part Type: Transistor - Manufacturer Part Number: MMBT2222ALT3G - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Name: onsemi **Pins:** - B [pin 1] - C [pin 3] - E [pin 2] ### Q2 — [MMBT2222ALT3G](https://www.flux.ai/adrian95/mmbt2222alt3g~vum.md) - Part Type: Transistor - Manufacturer Part Number: MMBT2222ALT3G - Datasheet URL: https://www.onsemi.com/pdf/datasheet/mmbt2222lt1-d.pdf - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Name: onsemi **Pins:** - B [pin 1] - C [pin 3] - E [pin 2] ### Q3 — [MMBT2222ALT3G](https://www.flux.ai/adrian95/mmbt2222alt3g~vum.md) - Part Type: Transistor - Manufacturer Part Number: MMBT2222ALT3G - Datasheet URL: https://www.onsemi.com/pdf/datasheet/mmbt2222lt1-d.pdf - Manufacturer Name: onsemi - License: https://creativecommons.org/licenses/by/4.0/ **Pins:** - B [pin 1] - C [pin 3] - E [pin 2] ### U1 — [MCP73871](https://www.flux.ai/kicad-part-library/mcp73871~kg6.md) - Manufacturer Part Number: MCP73871-2CCI/ML - Package or Case Code: QFN-20-1EP_4x4mm_P0.5mm_EP2.5x2.5mm - JLCPCB Part Class: Extended Part - Datasheet URL: http://www.mouser.com/ds/2/268/22090a-52174.pdf - Role Details: Single-cell LiPo charger/power-path IC locked to MCP73871-2CCI/ML 4.20 V QFN-20 variant for JLCPCB/LCSC sourcing; same MCP73871 QFN-20 pinout family per datasheet. - Part Type: Power Management - Manufacturer Name: Microchip **Pins:** - ~{PG} [pin 6] - ~{TE} [pin 9] - CE [pin 17] - IN [pin 19] - IN [pin 18] - OUT [pin 20] - OUT [pin 1] - PROG1 [pin 13] - PROG2 [pin 4] - PROG3 [pin 12] - SEL [pin 3] - STAT1/~{LBO} [pin 8] - STAT2 [pin 7] - THERM [pin 5] - V_{BAT_SENSE} [pin 16] - V_{BAT} [pin 14] - V_{BAT} [pin 15] - V_{SS} [pin 21] - V_{SS} [pin 11] - V_{SS} [pin 10] - VPCC [pin 2] ### U2 — [MCP1703Ax-330xxTT](https://www.flux.ai/kicad-part-library/mcp1703ax-330xxtt~9wn.md) - JLCPCB Part Class: Extended Part - Datasheet URL: http://ww1.microchip.com/downloads/en/DeviceDoc/20005122B.pdf - Manufacturer Part Number: MCP1700T-3302E/TT - Manufacturer Name: Microchip - Role Details: 3.3 V low-Iq LDO substituted to MCP1700T-3302E/TT for LCSC/JLC sourcing. Datasheet confirms same SOT-23 pin order as current footprint: pin 1 GND, pin 2 VOUT, pin 3 VIN; requires 1 µF input/output capacitors already present. - Package or Case Code: SOT-23 **Pins:** - GND [pin 1] - VI [pin 3] - VO [pin 2] ### U3 — [STM32L031K4U6](https://www.flux.ai/vasyl/stm32l031k4u6~gy9.md) - Part Type: Microcontroller - Datasheet URL: http://www.st.com/content/ccc/resource/technical/document/datasheet/aa/5d/77/ad/1a/59/4a/b9/DM00140359.pdf/files/DM00140359.pdf/jcr:content/translations/en.DM00140359.pdf - Manufacturer Part Number: STM32L031K4U6 - Manufacturer Name: STMicroelectronics **Pins:** - BOOT0 [pin 31] - NRST [pin 4] - PA0 [pin 6] - PA1 [pin 7] - PA10 [pin 20] - PA11 [pin 21] - PA12 [pin 22] - PA13 [pin 23] - PA14 [pin 24] - PA15 [pin 25] - PA2 [pin 8] - PA3 [pin 9] - PA4 [pin 10] - PA5 [pin 11] - PA6 [pin 12] - PA7 [pin 13] - PA8 [pin 18] - PA9 [pin 19] - PB0 [pin 14] - PB1 [pin 15] - PB2 [pin 16] - PB3 [pin 26] - PB4 [pin 27] - PB5 [pin 28] - PB6 [pin 29] - PB7 [pin 30] - PB8 [pin 32] - PC14 [pin 2] - PC15 [pin 3] - VDD [pin 17] - VDD [pin 1] - VDDA [pin 5] - VSS [pin 33] ### U4 — [QMC5883L](https://www.flux.ai/lcsc/qmc5883l~fn19.md) - LCSC Part Number: C2847467 - JLCPCB Part Class: Extended Part - Symbol Style: parametric-v1 - Part Type: Magnetic Sensors - License: https://creativecommons.org/licenses/by/4.0/ - Role Details: JLC/LCSC substitution from QMC5883L to QMC5883P candidate in same 3x3 mm LGA-16 package family. Firmware must use a QMC5883P-capable driver/register map before production. - Datasheet URL: https://www.lcsc.com/datasheet/C976032.pdf?spm=wm.sxq.inf.ggs&lcsc_vid=FlkNBAIDRQULVABfFAVZBgZVFVZYBgZSQ1NeBVIFQlExVlNeR1RZUVJRQ1VcVTsOAxUeFF5JWBYZEEoKFBINSQcJGk4dAgUUFAk%3D - Manufacturer Part Number: QMC5883P - Manufacturer Name: QST - Package or Case Code: LGA-16_L3.0-W3.0-P0.50-BL_SQ **Pins:** - C1 [pin 10] - DRDY [pin 15] - GND [pin 11] - GND [pin 9] - NC [pin 5] - NC [pin 6] - NC [pin 7] - NC [pin 3] - NC [pin 14] - S1 [pin 4] - SCL [pin 1] - SDA [pin 16] - SETC [pin 12] - SETP [pin 8] - VDD [pin 2] - VDDIO [pin 13] *The full schematic, PCB layout, bill of materials, and interactive design are available at [https://www.flux.ai/brooks/solar-dashboard-compass-sxtuu~7t](https://www.flux.ai/brooks/solar-dashboard-compass-sxtuu~7t).* --- *Generated from [https://www.flux.ai/brooks/solar-dashboard-compass-sxtuu~7t](https://www.flux.ai/brooks/solar-dashboard-compass-sxtuu~7t)*