Test Points
These pins are made available just in case they become necessary to your project. The six
pins bundled up together are connected to the Thing’s on-board SPI flash memory, but if you
really need the extra GPIO, or want to experiment with the pins, they’re available.
The RST pin is more useful, but we didn’t leave room to break it out – at least not
directly. RST is tied through a 0.1µF capacitor to the DTR pin, to allow for automatic reset
during programming. For many applications that need the RST pin, toggling the DTR pin
works as well. Putting the ESP8266 into deep sleep is one such application.
Selecting the Antenna
The Thing’s default WiFi antenna is a PCB trace antenna based on this TI app note. It’s cost-
effective and actually works really well!
If you need to connect a more sensitive antenna to the chip, a U.FL connector is also
available on the board, but isn’t connected by default to the ESP8266’s antenna pin. To
connect this antenna to the chip, you’ll need to heat up the 0Ω resistor and rotate it 90°:
An (ugly, uncleaned) resistor swapped from printed antenna to U.FL antenna.
A soldering iron, pair of tweezers, (2) steady hands, and good set of eyes should be enough
to accomplish the task.
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