Required Control Pins:
BUSY - this pin is an input from the AirLift, it will let us
know when its ready for more commands to be sent.
This is 3.3V logic out, can be read by 3-5V logic. This
pin
must be connected.
RST- this pin is an output to the AirLift. Set low to put the
AirLift into reset. You should use this pin, even though
you might be able to run for a short while without it, it's
essential to 'kick' the chip if it ever gets into a locked up
state. Level shifted so can be 3-5V logic
Optional Control Pins:
GPIO0 - this is the ESP32 GPIO0 pin, which is used to
put it into bootloading mode. It is also used if you like
when the ESP32 is acting as a server, to let you know
data is ready for reading. IIt's not required for WiFi, but
you'll need to connect it to use BLE mode. Solder the
pad on the bottom of the shield to connect it.
RX & TX - Serial data in and Serial data out, used for
bootloading new firmware, and for communication when
in BLE mode. Leave disconnected if not using BLE or
when not uploading new WiFi firmware to the AirLift
(which is a rare occurrence). You'll need to solder the
two pads on the bottom of the shield to use these pins.
SD Card Interface
There's a lot of space available on this shield so we also stuck
on a micro SD card holder, great for datalogging or storing
data to transmit over WiFi.
In addition to the shared SPI pins, the SD (chip select) pin is
also used. It can be re-assigned to any pin by cutting the trace
underneath the board and rewiring. If the SD card is not used,
the SD pin can be used for any other purpose
LEDs
© Adafruit Industries
https://learn.adafruit.com/adafruit-airlift-shield-esp32-wifi-co-processor
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