Okay!

Here's what I've got so far:

- The scheme of 3.3v going to BATT, VDD_IO and VREG_ENA all tied together worked perfectly.

- To get the 3.3v I had to change the way I was powering the Arduino. Before: The Pololu supplies 5v to everything, including the 5V rail on the Arduino and the 5V rail on the Betz board. After: Pololu only supplies 5v to the "VIN" pin on the Arduino, and then the Arduino's voltage regulator puts out both 5V and 3V on its 5v and 3V pins. The 5v pin powers the MAX232 chip and the reset/pair button, the 3V pin powers the Betz board into its 3v3 pin.

- Simply not supplying any voltage to the 5v pin on the Betz board (having it disconnected) worked.

- Throwing the 2-pole switch to the down/right/off position worked, and it was not necessary to cut the connection to anything. No voltage to the linear regulator that way. (I haven't tried finding out what happens if I turn that switch to the On position).

- No hot chips!

- Digital I/O works.

- 2k Pullup resistors on the WT32i TX line are no longer needed, serial data is clean now without them.

- I'm still leaving the voltage divider in place on the RX line of the WT32i though. That is also working.

- Here's a fun one: The reset circuit with the diode and the voltage divider, and the corresponding reset line code, are no longer needed. The chip powers up and stays powered without needing the reset button.

- The red LED on the Betz board does not light up any more. I don't know if that's because the voltage going into it is only 3v now instead of 4v, or if it's because the LED0 pin on the chip no longer does its "stuff" in "pure 3v always on" mode. In any case, that LED is no longer important to indicate anything we need to know. The chip Just Works now and it's always powered as long as we apply power to it.

- All of the above, converting this thing to run on 3v, solved several intermittent problems I was having with its behavior and pairing. It's now working and pairing reliably.

I'll be updating my docs/code shortly with all this information. Right now the docs still have stuff about the reset line and the pullup resistor and such.

I have a few remaining issues in software and hardware design, feel free to browse https://github.com/tfabris/BlueGigaEmpeg/issues if you're curious. After I solve a few of those I'll do another round of PCB design.