Description The AC Measure Unit is an isolated single-phase AC measurement unit for M5Stack projects. Based on an STM32G030 and HLW8032 acquisition solution, the AC Measure Unit (HLW8032) can monitor current, voltage, and power data in real time and expose the readings through an I2C interface. For safer signal separation, the isolated AC measurement module integrates a B0505ST16-W5 AC isolation converter and communicates between the measurement side and STM32 through an EL357 optocoupler. This design helps the I2C AC power sensor fit power information collection, remote appliance monitoring, metered sockets, and smart electrical control projects. Note: Input Voltage The operating measurement range must be AC 100-240V at up to 10A. If the input is outside this range, the AC Measure Unit may not work properly. AC wiring can be hazardous, so installation should be handled only by qualified users who understand mains-voltage safety. Features Single-phase AC measurement: monitors voltage, current, and power for AC 100-240V / 10A circuits. Isolated acquisition design: the isolated AC measurement module uses B0505ST16-W5 isolation and EL357 optocoupler communication. HLW8032 acquisition: the dedicated AC metering chip supports real-time power information collection. STM32 control: STM32G030 Cortex-M0+ MCU with 64 KB Flash and 8 KB RAM manages communication and data processing. I2C interface: the I2C AC power sensor communicates at address 0x42 through Grove PORT.A wiring. Development support: the AC Measure Unit (HLW8032) supports Arduino, UIFlow, Home Assistant, and I2C protocol resources. Specifications MCU STM32G030F6P6 AC Acquisition Chip HLW8032 Isolation Chip B0505ST16-W5 Optocoupler Communication Chip EL357NB Communication Interface I2C @0x42 Measured Voltage and Current AC 100-240V @10A Product Size 56.0 x 24.0 x 10.3mm Product Weight 8.4g Package Size 138.0 x 93.0 x 11.3mm Gross Weight 16.9g Applications Smart home appliance power monitoring Metered sockets and smart Wi-Fi socket prototypes EV charging pile monitoring and test fixtures Streetlight control and energy data collection Remote AC device monitoring through microcontroller systems Product List 1 Unit AC Measure 1 HY2.0-4P Grove Cable (20cm) 1 VH3.96-4P Terminal Other Content The AC Measure Unit uses Grove PORT.A for controller communication while the terminal side is wired into the AC power path. Follow the documented terminal mapping carefully: L1 and L2 are line connections, N2 is neutral, and N1 is listed as ground reference in the wiring diagram. Grove Pin Signal Black GND Red 5V Yellow SDA White SCL AC Terminal Connection L1 Line input N1 Ground reference L2 Line output N2 Neutral Use appropriate insulation, enclosure design, and strain relief around the isolated AC measurement module. After installation, verify readings through the I2C AC power sensor interface before connecting the system to unattended operation. Resources Product documentation Schematic PDF Model size PDF Arduino library UIFlow1 documentation UIFlow2 documentation Home Assistant integration Internal firmware I2C protocol PDF HLW8032 datasheet STM32G030 datasheet FAQ What can the AC Measure Unit monitor? It monitors single-phase AC voltage, current, and power data through the HLW8032 acquisition chip. What is the I2C address? The AC Measure Unit (HLW8032) communicates through I2C at address 0x42. Can it be used directly on mains voltage? It is designed for AC 100-240V up to 10A, but mains wiring is dangerous and should only be installed by qualified users with proper safety protection.
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