[BK7231N - CBU] TONGOU TO-Q-SY1-JWT Din Rail Wifi Switch with power metering

The discussion centers on the TONGOU TO-Q-SY1-JWT DIN Rail WiFi switch featuring the BK7231N chipset (CBU module) and integrated power metering via the BL0942 chip. The device uses a magnetic polarized relay driven by an MD7620 bridge driver IC, requiring 100-200 ms pulses to toggle relay contacts, which then hold position without continuous power. Initial firmware lacked support for the MD7620 bridge driver, but a pull request was submitted and merged to add this functionality. Proper pin configuration is critical: pins 24 and 26 must be assigned as BridgeFWD and BridgeREV respectively, not as simple relay outputs (Rel/Rel_n), to avoid continuous coil energizing and overheating. The bridge driver should start automatically on reboot, but manual startDriver Bridge command may be necessary if autostart is disabled. Adjusting the bridge pulse length is possible but not fully documented; some users reported issues with pulse timing affecting relay operation. Flashing the device can be done without desoldering the module by connecting to UART pins, though some users experienced difficulties with programming stability and recommended using hid_download_py or the BK7231GUIFlashTool. Power metering calibration remains imperfect, with non-zero power readings at no load and issues distinguishing real, apparent, and reactive power. Firmware flags and startup commands can influence metering behavior and device startup states after power outages. Community members shared updated JSON templates for device configuration, emphasizing correct pin roles and startup commands to enable bridge driver and energy monitoring. The discussion also touched on hardware modifications for broken pads and soldering techniques for module removal.
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