Hello. I was looking for feedback on a project to add low-cost functionality to smart plugs. In my case, I wanted to add bluetooth functionality (btproxy, espresense) to rooms without having to add separate USB power supplies and without having to block plugs.
I have quite a few Sonoff S31 wifi plugs running ESPHome on esp8266. One of the downsides of this chip is that it doesn’t support the BLE functionality required for btproxy and espresense.
The route I took was to add esp32 c3 minis by soldering to the existing pads (3.3v/gnd) of the S31, and likewise on the C3. There’s room inside to mount the C3 to the outer wall using double-sided Gorilla tape. It seems to work well and meets the goal.
I’m mainly curious if anyone finds this to be particularly hacky (electrical, thermal, signal, etc.), or does it seem clean enough. All feedback welcome.
In the USA, insurance companies will find any reason at all to deny a claim. If they get a whiff that there was a modified electrical device in the structure, it would be reason enough, even if the device was no where near the origin of the damage.
Yes, it’s kludgey. Use shorter wires. Consider using wire-wrap wire. On the C3 solder the wires perpendicular to the board. Add a dab of hot glue to the connections for strain relief. Gorrilla tape eventually fails; consider hot glue.
The onboard power supply is usually designed to an inch of its life to power the rest of the board, and not a nanowatt more. As a manufacturer, when you are churning these devices out by the millions you can’t afford to overspecify components.
If your substitute (not additional) SOC draws less or the same amount of current under all conditions, you should be fine, otherwise expect a device that runs hotter, has shorter life, or even decides to release embedded smoke or catch fire.
You are basically redesigning a mains powered device, to control mains power. If your skill levels are up to it, fine, but please be aware of the implications if you overlook a critical design issue that the original vendor solved during their R&D phase, and subsequent updates based on device performance experience out in the field.
Is your new SOC one of those poorly designed chinese clones that has sketchy WiFi performance due to use of the red chip WiFi antenna?
Thanks for the feedback. Given the concerns raised here, I’m going to abandon this direction. While it technically “works” and seems stable, there seems to be too much outlier risk. I’m still searching for a good way to deploy a number of BLE-based sensors without consuming an AC plug for each sensor.
Most electronics around the house already have USB sockets & are powered on continuously or have an option to provide usb power when in standby. All you really need is a short usb cable hooked up to that C3.
Just walking around my house, I have:
Phone chargers with multiple usb ports.
Kitchen sockets with USB.
PS5.
TV.
Android box.
Considering that you only need 1-2 proxies per floor, I’m sure you can avoid using an actual socket if you have any of these devices around the house.
