[Zigbee] ELVICO ELC-SP02 Zigbee Smart Plug Teardown: BL702C10, BL0937
Here is a teardown of an 'ELVICO Smart Plug'. It is intended for Zigbee using the eWelink platform. I have been hunting for bouffalolab-based devices, as my project has been porting those chips to Zephyr RTOS for a few years, and we just got BLE working, enabling usages similar to OpenBeken or Tasmota.
The marking on the outside is 'ELC-SP02'. The case is thick plastic and heat-closed by tabs on the edges, and very hard to open. The board inside is held by a single screw, then easily pulls out.
The design is as such:
Ground is passed through from front to back.
Zigbee is provided by a BL702C10 chip with date markings of 2025, mounted on an EWL-ZBS02-LG_V2 module marked 2023 (??). This is a 1 megabyte flash version, and the module provides its 32 MHz crystal but not much else.
The energy metering chip is BL0937, there are 2 LEDs available to control, and a button.
5 V power is provided by a BP2525 chip, and 3.3 V power is provided by an AMS1117 LDO.
The switching capacity is provided by a 'FANHAR' FH17-1A2TLE 5 V relay.
The button is connected to GPIO27, LED 1 is connected to GPIO8, LED 2 is also connected to GPIO27 via a 10 kΩ resistor.
BL0937 CF, CF1 and SEL go to the chip via 1 kΩ resistors. CF goes to GPIO2, CF1 goes to GPIO1, SEL goes to GPIO15.
The relay is driven by GPIO14 -> 1.5 kΩ -> mosfet.
The marking on the outside is 'ELC-SP02'. The case is thick plastic and heat-closed by tabs on the edges, and very hard to open. The board inside is held by a single screw, then easily pulls out.
The design is as such:
Ground is passed through from front to back.
Zigbee is provided by a BL702C10 chip with date markings of 2025, mounted on an EWL-ZBS02-LG_V2 module marked 2023 (??). This is a 1 megabyte flash version, and the module provides its 32 MHz crystal but not much else.
The energy metering chip is BL0937, there are 2 LEDs available to control, and a button.
5 V power is provided by a BP2525 chip, and 3.3 V power is provided by an AMS1117 LDO.
The switching capacity is provided by a 'FANHAR' FH17-1A2TLE 5 V relay.
The button is connected to GPIO27, LED 1 is connected to GPIO8, LED 2 is also connected to GPIO27 via a 10 kΩ resistor.
BL0937 CF, CF1 and SEL go to the chip via 1 kΩ resistors. CF goes to GPIO2, CF1 goes to GPIO1, SEL goes to GPIO15.
The relay is driven by GPIO14 -> 1.5 kΩ -> mosfet.
Comments
These modules are cool, but I noticed an interesting issue that is not present here. A socket marked as 20A failed after a few weeks with a load of around 15A. The relay was damaged and melted. Fortunately... [Read more]