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SAE J1772:2010 EVSE Control Board Module Development

This is a continuation of the first version with the LCD display that was built in February 2010.

The new version continues as a partial breadboard design to finalize the options and best pin selections.

This time the goal is to interface with a RS-232 serial port using simple commands and status messages.  For the most part it is redirection the LCD data to the serial port.  New functions are being added so the serial port can enable or disable the charging cycle.  The serial data can control a human interface graphic program.

By the middle of February 2011 we hope to have the next generation circuit boards.

The design target is LCD with basic start/stop buttons or a serial communications design that uses RS-232, RS-485, USB, or ZigBee.

The module produces the J1772 pilot signal and monitors it do determine what is needed in the charging cycle.

When the J1772 requirements are met, the control board has an output that actuates a power contactor that supplies electrical power to the J1772 connector and the vehicle.

The board operates on safe 12 or 24 volts DC.


The first serial control unit is done and being evaluated.

Simple commands and messages allow remote control from  your computers human interface.

The next project is adding hardware to monitor power voltage and current to use the DSP to calculate the power used and report it.
Many people are interested in the actual charge power.  Businesses offering free public charging want to know what this service is actually costing them and how many people are using it.

This will lead to a universal board, well a first generation, that can do a number of different interfaces and control options.  From simple start/stop and a few LED's to complex serial communications.


We have come back to reality.

A basic unit with LCD or LED.  For the time being we are going to work on the basic unit, clean up the design and get it into peoples hands. 



All new PCB design is almost ready to send out and get made.  It ended up as a 4 layer board to get all of the build options included.  It still has jumpers but as the options get refined they will get reduced

There are 3 inputs for start, stop, and inhibit switches.

Data can be displayed on the LCD, 4 LEDs, a 10/100 network port, or Zigbee.

An option is being planned for measuring the power used by the EVSE.

We hope to have units for evaluation in 4 weeks.


The PCB have arrived and the first group are about 1/3 built.  Power supplies are operating and things are working as planned..

Another week or two and the new board will be up and running.  There will be two versions initially, LCD and Ethernet.

Also in the good news department one of the original boards is in a  EVSE and charges a Tesla.

That original board sure seems ugly today but the boards are 95% the same.


The first few boards are build and ready to be tested.  The display identifies itself and things seem to be working.

Calibration, output voltages, and timing need to be verified.

The board shown has the LCD and switch inputs for START, STOP and INHIBIT.  Other configurations will have Ethernet 10/100 connections.

This is a good looking board and does not have the prototype look of the previous revision, but for generation 3 that should be expected.

On the back side there are 4 status LEDS: Ready, Connected, Charging, and Error.

For the J1772 Pilot signal there also is the switches to set the available current.




modular EV power LLC, all rights reserved, 2011