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Roadster Sport 2.5 & S100D
Jun 23, 2009
The Netherlands
Open Chargeport

What is it?
As the name suggests, it's a transmitter that will open the charge port of a Model S.

Last week I received my EU spec model S, and charged a few times with the cable Tesla supplies with the car.
The button to open the Charge port door, really is a nice feature.
As there is no such thing on a standard Type 2 charge cable, i now have to open the car door, touch the battery icon, and select open charge port. Not very convenient.

Therefore i wanted to make my own transmitter that opens the chargeport, and that can be fitted into a standard Type2 plug.

Credits to Banahogg who documented his attempts to analyze the RF data here
which helped me finish this project in a few days.

The components needed:

I used a 433 Mhz module connected to a PIC microcontroller. (US model S, might require a 315Mhz module)
Only a few other components are required.

1x PIC12F1822 microcontroller
1x Lithium cell, 3V
2x 100nf capacitor
1x 10uf capacitor
1x pushbutton

Feel free to build your own Open Chargeport, or improve it. PIC sourcecode can be downloaded from Github:

The chip inside the Model S charge plug is a Si4010, i have made a version for this chip as well, will upload it to Github soon.

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  • Informative
Reactions: Gatsojon
Which exact 433Mhz channel is it? Since I have a lot of 433Mhz transmitter lying around here.

The frequency is 433.92 MHz. Please see the datasheet of the Aurel TX SAW/MID for more info.
Important is that you use a AM/ASK module. FSK will not work.

@mknox Smart meters and any other devices that transmit on this frequency will not open the charge port, as it's a 50 bit code that is used. The chance of that being the same as a smart meter is almost zero.
Interesting idea. I get "invalid attachment" when I try to download the source. What is the waveform you are sending? I was thinking of a quick proto with an arduino.

Sorry, fixed the download link.

The sourcecode is for a Microchip PIC 12F1822 chip, and written in assembler.
The HEX file is also included, which you can directly program in the PIC chip.

It takes less then 100 words of program space, and doesn't use any peripherals other then one timer. So it should be relatively easy to use another microcontroller.
This is the actual transmitter circuit card in the UMC:

S1 is the switch for the J1772 proximity circuit. R1 is the 150 ohm resistor that signals the proximity pin is connected to the car. When the S1 switch is pressed (open), the 330 ohm resistor R2 is added in series to R1, creating 480 ohms to ground (150 + 330) which signals to disconnect. Yep, that simple.

S2 is the switch for the transmitter that opens the Model S charge port. It is powered from the UMC with 3.3 volts from the blue wire (not pictured).

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My wife would probably kill me if I added yet another project to my UTAH list (Unfinished Things Around the House). If someone else has a smaller UTAH list, I'd love to see a keyfob version, as small as possible, and would pay for it.
I've asked the above poster for the board and will order the Silicon Labs dev board set up shortly. It comes with a fob and a receiver. With luck, I can use the receiver to determine the code then program that into the fob. I'll check DigiKey to see if they sell just the fobs (for those that want one).

I'm a digital guy and, although I've did a good bit of work years ago with the SL 8051 stuff, I'm not really up on transmission protocols. I'll try to "educate myself up" on the basics of AM/ASK versus FSK while I'm waiting on the demo board. By chance has anyone absolutely confirmed the operating frequency for the US as low 300s is not one of the three frequencies offered in the dev. board sets?
"Important is that you use a AM/ASK module. FSK will not work."