Adafruit ESP32 WiFi User manual

Adafruit AirLift Shield - ESP32 WiFi Co-Processor

Created by Brent Rubell

Last updated on 2021-03-29 01:04:51 PM EDT

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Guide Contents

Guide Contents Overview Pinouts

Power Pins SPI Interface Pins ESP32 Control Pins SD Card Interface LEDs Prototyping Area

Assembly Installing Standard Headers

Stack Alert!

CircuitPython WiFi

CircuitPython Microcontroller Pinout

CircuitPython Installation of ESP32SPI Library CircuitPython Usage Internet Connect! What's a secrets file? Connect to WiFi Requests

HTTP GET with Requests HTTP POST with Requests Advanced Requests Usage

WiFi Manager CircuitPython BLE CircuitPython BLE UART Example Adafruit AirLift ESP32 Shield Wiring Update the AirLift Firmware Install CircuitPython Libraries Install the Adafruit Bluefruit LE Connect App Copy and Adjust the Example Program Talk to the AirLift via the Bluefruit LE Connect App Arduino WiFi Library Install First Test

Arduino Microcontroller Pin Definition

WiFi Connection Test Secure Connection Example

JSON Parsing Example Adapting Other Examples

Upgrade External ESP32 Airlift Firmware External AirLift FeatherWing, Shield, or ItsyWing

Upload Serial Passthrough code for Feather or ItsyBitsy

External AirLift Breakout Code Usage

Install esptool.py

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Burning nina-fw with esptool Verifying the Upgraded Firmware Version

Arduino CircuitPython

Downloads

Files Schematic Fab Print

Overview

Give your Arduino project a

lift

with the Adafruit AirLift Shield (https://adafru.it/F6v) - a shield that lets you

use the powerful ESP32 as a WiFi or BLE co-processor. You probably have your favorite Arduino-

compatible (like the Metro M4 (https://adafru.it/A5S) or the classic Metro

328 (https://adafru.it/METROXMETR)) that comes with its own set of awesome peripherals and lots of

libraries. But it doesn't have WiFi or BLE built in! So let's give that chip a best friend, the ESP32. This chip

can handle all the heavy lifting of connecting to a WiFi network and transferring data from a site, even if it's

using the latest TLS/SSL encryption (it has root certificates pre-burned in).

Having WiFi managed by a separate chip means your code is simpler, you don't have to cache socket

data, or compile in & debug an SSL library. Send basic but powerful socket-based commands over 8MHz

SPI for high speed data transfer. You can use any 3V or 5V Arduino, any chip from the ATmega328 and up

(although the '328 will not be able to do very complex tasks or buffer a lot of data). It also works great with

CircuitPython, a SAMD51/Cortex M4 minimum required since we need a bunch of RAM. All you need is the

SPI bus and 2 control pins plus a power supply that can provide up to 250mA during WiFi usage.

The ESP32 also supports BLE (Bluetooth Low Energy), though not simultaneously with WiFi. Many of our

CircuitPython builds include native support for ESP32 BLE. You use a few control pins and the RXI and

TXO pins to talk to the ESP32 when it's in BLE mode.

We placed an ESP32 module on a shield with a separate 3.3V regulator, and a tri-state chip for MOSI so

you can share the SPI bus with other shields. We also tossed on a micro SD card socket, you can use that

to host or store data you get from the Internet. Arduinos based on the ATmega328 (like the UNO) cannot

use both the WiFi module and SD library at the same time, they don't have enough RAM. Again, we

recommend an M0 or M4 chipset for use with Arduino, M4 for CircuitPython!

Comes fully assembled and tested, pre-programmed with ESP32 SPI WiFi co-processor firmware that you

can use in CircuitPython to use this into WiFi co-processsor (https://adafru.it/Evl). We also include some

header so you can solder it in and plug right into your Arduino-compatible, but you can also pick up a set

of stacking headers to stack above/below your board.

We've tested this with all our Metros and it should work just fine with them except the Metro M4

Airlifts (https://adafru.it/F6o) (because they already have WiFi!). For use in Arduino , the '328 and '32u4 you

can do basic connectivity and data transfer but they do not have a lot of RAM so we don't recommend

them - use the Metro M0, M4 or similar, for best results! For CircuitPython use, a Metro M4 works best -

the M0 series does not have enough RAM in CircuitPython.

The firmware on board is a slight variant of the Arduino WiFiNINA core, which works

great! (https://adafru.it/E7O) At this time connection to Enterprise WiFi is not yet supported.

Pinouts

There's a lot jam-packed into this shield! Let's take a look at what we've got going on.

Power Pins

GND - Common power/logic ground.

3V - this is the output from the 3.3V regulator. The regulator can supply 500mA peak but half of that

is drawn by the ESP32, and it's a fairly power-hungry chip.

5V - This is the input to the regulator

IOr - This is IORef, the IO voltage we will communicate with and is required.

SPI Interface Pins

Both ESP32 and SD card use SPI to send and receive data. These pins are labeled CLK MISO MOSI and

have level shifting so you can use this shield with 3.3V or 5V microcontroller boards.

By default the 2x3 pin ICSP header on the right hand side is where the SPI signals are found.

ESP32 Control Pins

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

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

There is a small RGB LED to the left of the ESP32. These RGB

LEDs are available in the Arduino and CircuitPython libraries if

you'd like to PWM them for a visual alert. They're connected

to the ESP32's pins 26 (Red), 25 (Green), and 27 (Blue).

Prototyping Area

We have a big grid of prototyping holes and power rails if you

want to make some custom circuitry!

Assembly

Installing Standard Headers

The shield comes with 0.1" standard header. Standard header does not permit stacking but it is

mechanically stronger and they're much less expensive too! If you want to stack a shield on top, do not

perform this step as it is not possible to uninstall the headers once soldered in! Skip down to the bottom

for the stacking tutorial

Break apart the 0.1" header into 6, 8 and/or 10-pin long pieces

and slip the long ends into the headers of your Arduino.

Place the assembled shield on top of the header-ed Arduino

so that all of the short parts of the header are sticking through

the outer set of pads

Solder each one of the pins into the shield to make a secure

connection

That's it! Now you can install the 2x3 header

Solder the 2x3 header so that it's pointing downwards

Stack Alert!

If you want to stack a shield on top of the WiFi Shield, you'll want to pick up some stacking headers and

use those instead of the plain header shown here!

Wanna stack? This tutorial shows how to use the plain header

to connect to an Arduino. If you want to use stacking

headers (https://adafru.it/dsu), don't follow these steps!

Start by sliding the 10 pin, 2 x 8 pin and 6-pin stacking

headers into the outer rows of the shield from the top. Then

flip the board over so its resting on the four headers. Pull on

the legs if necessary to straighten them out.

Tack one pin of each header, to get them set in place before

more soldering. If the headers go crooked you can re-heat the

one pin while re-positioning to straighten them up

Adafruit ESP32 WiFi User manual

Specifications and Main Features

Frequently Asked Questions

User Manual