Someone shared with me today that they were using the EV Sim for automated EVSE testing. That inspired me to think of a way to replace the display with a connection to a computer so that interactions and measurements could be automated.
The result is the EV Sim Remote. It swaps out the ATTIny841 for the ATTiny84. The upgrade gives us a USART for serial I/O. That's connected to a CY7C65213 USB UART and then to a micro USB connector. Instead of the DIP switches, the 3 resistors are switched in and out of the pilot line with N MOSFETs controlled by GPIO pins on the controller.
The serial port will be set up for 9600 8N1. The output format will be printable and consist of the measured frequency, duty cycle, minimum and maximum voltage. To change state, you simply send an "A", "B", "C" or "D". Unlike the backpack variant, there is no mechanism to remove the diode.
Yes, this could be done instead with USBTiny, but then I'd have to make a CDC device and this is just easier.