Solar-Powered Dashboard Compass
proceed
Thought for 18 sec
I’ll proceed with post-substitution layout cleanup, then route the PCB and run DRC/airwire checks. I’ll keep this to the routing phase and report any manufacturing blockers separately.
Worked for 40 mins 39 sec
Routed the PCB: auto-routing completed and added 558 trace/via nodes while preserving the portrait board, centered vertical display stack, and isolated magnetometer placement.
Open blocker:
- The board is not yet JLC-ready because U3’s STM32 footprint has duplicate exposed-pad thermal sub-pads overlapping the grounded center pad. Final checks show 9 overlapping-copper errors and 1 remaining GND airwire, all tied to that U3 footprint issue.
Suggested next steps:
- Replace/correct U3’s footprint with a clean STM32L031 UFQFPN/QFN-32 exposed-pad footprint.
- Re-run DRC and route cleanup after the footprint fix.
- Re-check JLC/LCSC BOM status before manufacturing export.
Fix U3 footprint
Find alternate MCU
Rerun DRC after fix
Review manufacturability
Preserve layout intent
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Firmware Pin Map — Solar Dashboard Compass
MCU
STM32L031K4U6 (U3), 3.3 V logic.
I2C Magnetometer
- PB6: I2C_SCL → QMC5883L SCL, 10 kΩ pull-up to 3V3
- PB7: I2C_SDA → QMC5883L SDA, 10 kΩ pull-up to 3V3
- PB8: MAG_DRDY → QMC5883L DRDY
- QMC5883L I2C address: 0x0D
Seven-Segment Segment Lines
These are shared across all three digits through 47 Ω series resistors:
- PA0: segment A
- PA1: segment B
- PA2: segment C
- PA3: segment D
- PA4: segment E
- PA5: segment F
- PA6: segment G
- Decimal points are not used and are marked no-connect.
Digit Enables
Common cathodes are switched with MMBT2222A low-side transistors:
- PA7: digit 1 enable via Q1
- PB0: digit 2 enable via Q2
- PB1: digit 3 enable via Q3
Boot / Reset
- NRST: 10 kΩ pull-up to 3V3 with 0.1 µF to GND
- BOOT0: pulldown resistor to GND
Firmware Behavior Recommendations
- Read QMC5883L at 10–50 Hz, then average/filter heading.
- Apply hard-iron/soft-iron calibration in firmware.
- Multiplex display at >100 Hz total refresh to avoid visible flicker.
- Use PWM dimming and blank the display in low-light/no-solar conditions to reduce current draw.
- Store calibration offsets in nonvolatile memory if available.
MCU
I2C Magnetometer
Seven-Segment Segment Lines
Digit Enables
Boot / Reset
Firmware Behavior Recommendations
