WiFi
I'd like to integrate a inexpensive wifi controller and have it run the entire show. I'm currently learning a lot about ESP8266. I would replace the ATTiny85 controller and program the ESP8266 WiFi processor to directly drive the controller (click link for how).
One side effect of using the ESP8266 is that it doesn't have an ADC (that I can find), so I can't poll the voltage of the sense line to drive the vehicle state algorithm. That means I'll probably use an additional OpAmp/comparitor in an inverting "1-bit ADC". The ESP8266 will be skinny dumb and happy and just have code that checks...
| Sense Line | State | Description |
|---|---|---|
| All LOW | A | Off/Fault |
| Low/HIGH | B | Powers On, may be plugged in |
| All HIGH | C | Vehicle requested charge |
Still need denouncing (for noise); but the basic algorithm is something like...If we're in "B" and are changing state to "C", enable charging.
If we're charging and we ever see "A" or "B" stop charging
I'd like to go solid state. Dual opto-isiloted connected to a 40A triac. It's even cheaper and smaller and I can easily integrate it on the board. Example Circuit
Onboard power supplySo you feed the board 240VAC and a pico-sized (150ma) onboard power supply will convert it down to 3.2v for the controller.
Current sense
Use an inexpensive current sense. I can send back the current usage in status so it can be sent to the control website.
The Quadracorn
I'm building a four channel controller with all of the above. That may become my regular circuit that I'll use for everything. There's very little additional cost in making the circuitry I won't populate.
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