This is a method for using a Teensy 2.0 or Teensy 2.0++ as a serial bridge so that an Adafruit Huzzah can be programmed from the Arduino IDE on Mac OS X 10.11.
First, load the Mac2Teensy2HuzzahSerialBridge sketch onto the Teensy. Then, unplug the USB cable from the Mac and connect the Teensy and Huzzah as follows:
Connect V+ and Gnd as well as the serial RX/TX pins. Note that the RX of the Teensy is connected to TX of the Huzzah and vice-versa.
In addition, the Huzzah's GPIO0 pin should be connected to ground and the GPIO2 pin to +V in order to force the Huzzah into programming mode when it is powered on. Here is the complete setup ready for the USB cable to be plugged into the Mac.
- Load the Mac2Teensy2Huzzah.ino sketch onto the Teensy.
- Unplug the USB cable and connect the Teensy to the Huzzah as shown.
- Switch to your sketch that you want to load on the Huzzah
- Don't forget to change to Tools->Board: "Adafruit HUZZAH ESP8266". The Teensy's serial port should still be selected in Tools->Port.
- Plug the USB cable into the Mac and click "Upload".
- After the sketch compiles, you should see the Teensy's LED light up as the program is uploaded to the Huzzah's flash.
- Once the upload is complete, be sure to disconnect GPIO0 from ground and GPIO2 from V+.
Eagle files are included for making a permanent programmer setup with a Teensy 2.0: