Dehumidifier Control Board
Climate Control Board (Máy Hút Ẩm) firmware and layout dossier based on the STM32F103RCT6 main processor, ULN2003 Darlington drivers, and TM1637 display drivers.
01 / Case Study: Hardware Context
An industrial climate-control subsystem designed for commercial dehumidifiers. The board integrates high-voltage relay switching networks (up to 240V AC) side-by-side with high-precision temperature & humidity ADC interfaces, operating inside compact, enclosed metal housings.
Platform Architecture & Overview
The PRJ-MHA-STM32 project manages the application logic and driver subsystems for a domestic humidifier/dehumidifier unit (MHA). The hardware netlist was imported from Altium Protel formats and parsed into a unified composed configuration.
Main Components (BOM Inventory)
- MCU (U2): STM32F103RCT6 (LQFP64 packaging).
- Darlington Driver (U3): ULN2003 (SO-16) driving step motors, UV lamp, and Buzzer.
- Display Driver (U4): TM1637 (SOP-20) controlling a 6-digit $\times$ 8-segment matrix display.
- LDO Voltage Regulator (U1): 5.2V to 3.3V SOT-223 regulator.
Power Rails
- +12V: Main power rail driving Buzzer, UV lamp, and step motor.
- +5V: Supplies logic power to drivers, displays, and sensors.
- +3.3V: Powers MCU, NTC sensors, and Flash programming interfaces.
- VBAT: Connected to CR1220 battery for RTC backup.
MCU Port Assignment (Pin-to-Function Matrix)
- PA8-PA11: Mapped to
STEP1throughSTEP4for step motor control. - PA4-PA7: Analog sensor input channels
ADC0(Humidity),ADC1(Temperature),ADC2(Water Level float switch), andADC3(NTC Thermistor). - PB12-PB15: Display control interfaces
MCLK,MDIO,LCLK,LDIO. - PC6-PC9: Compressor relay control (
COMP), fan speeds (F1/F2/F3), and UV enable lines.
02 / Case Study: Design Bottleneck
Creepage and clearance limits between 240V AC lines and low-voltage MCU digital lines. Maintaining signal integrity on sensitive analog sensors placed close to high-current relay switching inductors and transformer nodes.
03 / Case Study: OmeraCode Resolution
The FootprintSanityGate verified LQFP64 footprint clearances and whitelisted spacing limits. The PowerDesignGate checked Bootstrap safety checks, while the TraceOptimizer routed differential signal pairs away from switching transformer nodes to isolate transient noise loops.
04 / Case Study: Evidence & Artifact Metrics
VERIFIED PHYSICAL PARAMETERS MANIFEST
- Creepage & Spacing Audit (Relays)
3.0mm physical spacing clearance validated between high voltage and digital paths.
- ADC Noise Coupling review
High-current loops isolated from ADC analog sense lanes.
- LQFP64 Solder Mask Clearance
Verified pin clearance boundaries against assembly limits.
- Darlington Driver Pin Sequencing
Ensured sequential trace mappings for the fan motor driver.