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Give your Arduino project a lift with the Adafruit AirLift Shield - 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 or the classic Metro 328) 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).

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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.

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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!

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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. 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.

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We've tested this with all our Metros and it should work just fine with them except the Metro M4 Airlifts (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! At this time connection to Enterprise WiFi is not yet supported.

Pinouts

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

Power Pins

adafruit_products_4285-pwr.png
  • 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

adafruit_products_4285-spi.png

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 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

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

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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, 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

Once you've tacked and straightened all the headers, go back and solder the remaining pins for each header.

Insert the 2x3 stacking header as shown.

Solder into place.

CircuitPython WiFi

It's easy to use the Adafruit AirLift breakout with CircuitPython and the Adafruit CircuitPython ESP32SPI module.  This module allows you to easily add WiFi to your project.

The ESP32SPI library requires a microcontroller with ~128KB of RAM or more. The SAMD21 will not work.

CircuitPython Microcontroller Pinout

To use the board's pins with the AirLift shield, copy the following lines into your code:

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esp32_cs = DigitalInOut(board.D10)
esp32_ready = DigitalInOut(board.D7)
esp32_reset = DigitalInOut(board.D5)

If you wish to use the GPIO0 pin on the ESP32 - solder the jumper on the back of the shield, highlighted below:

adafruit_products_4285-back-g0.png

Then, include the following code to use the pin:

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esp32_gpio0 = DigitalInOut(board.D6)

CircuitPython Setup

First make sure you are running the latest version of Adafruit CircuitPython for your board.

Next you'll need to install the necessary libraries to use the hardware. Thankfully, we can do this in one go. In the example below, click the Download Project Bundle button below to download the necessary libraries and the code.py file in a zip file. Extract the contents of the zip file, and copy the entire lib folder and the code.py file to your CIRCUITPY drive.

Your CIRCUITPY/lib folder should contain the following folders and files:

  • /adafruit_bus_device
  • /adafruit_esp32spi
  • adafruit_requests.mpy
CIRCUITPY

CircuitPython Usage

Copy the following code to your code.py file on your microcontroller:

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import board
import busio
from digitalio import DigitalInOut

from adafruit_esp32spi import adafruit_esp32spi

print("ESP32 SPI hardware test")

esp32_cs = DigitalInOut(board.D10)
esp32_ready = DigitalInOut(board.D7)
esp32_reset = DigitalInOut(board.D5)

spi = busio.SPI(board.SCK, board.MOSI, board.MISO)
esp = adafruit_esp32spi.ESP_SPIcontrol(spi, esp32_cs, esp32_ready, esp32_reset)

if esp.status == adafruit_esp32spi.WL_IDLE_STATUS:
    print("ESP32 found and in idle mode")
print("Firmware vers.", esp.firmware_version)
print("MAC addr:", [hex(i) for i in esp.MAC_address])

for ap in esp.scan_networks():
    print("\t%s\t\tRSSI: %d" % (str(ap['ssid'], 'utf-8'), ap['rssi']))

print("Done!")

Connect to the serial console to see the output. It should look something like the following:

adafruit_products_AirLift_Output.png

Make sure you see the same output! If you don't, check your wiring. Note that we've changed the pinout in the code example above to reflect the CircuitPython Microcontroller Pinout at the top of this page.

Once you've succeeded, continue onto the next page!

If you can read the Firmware and MAC address but fails on scanning SSIDs, check your power supply, you may be running out of juice to the ESP32 and it's resetting

Internet Connect!

Once you have CircuitPython setup and libraries installed we can get your board connected to the Internet. 

To get connected, you will need to start by creating a secrets file.

What's a secrets file?

We expect people to share tons of projects as they build CircuitPython WiFi widgets. What we want to avoid is people accidentally sharing their passwords or secret tokens and API keys. So, we designed all our examples to use a secrets.py file, that is in your CIRCUITPY drive, to hold secret/private/custom data. That way you can share your main project without worrying about accidentally sharing private stuff.

Your secrets.py file should look like this:

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# This file is where you keep secret settings, passwords, and tokens!
# If you put them in the code you risk committing that info or sharing it

secrets = {
    'ssid' : 'home ssid',
    'password' : 'my password',
    'timezone' : "America/New_York", # http://worldtimeapi.org/timezones
    'github_token' : 'fawfj23rakjnfawiefa',
    'hackaday_token' : 'h4xx0rs3kret',
    }

Inside is a python dictionary named secrets with a line for each entry. Each entry has an entry name (say 'ssid') and then a colon to separate it from the entry key 'home ssid' and finally a comma ,

At a minimum you'll need the ssid and password for your local WiFi setup. As you make projects you may need more tokens and keys, just add them one line at a time. See for example other tokens such as one for accessing github or the hackaday API. Other non-secret data like your timezone can also go here, just cause its called secrets doesn't mean you can't have general customization data in there!

For the correct time zone string, look at http://worldtimeapi.org/timezones and remember that if your city is not listed, look for a city in the same time zone, for example Boston, New York, Philadelphia, Washington DC, and Miami are all on the same time as New York.

Of course, don't share your secrets.py - keep that out of GitHub, Discord or other project-sharing sites.

Connect to WiFi

OK now you have your secrets setup - you can connect to the Internet using the ESP32SPI and the Requests modules.

First make sure you are running the latest version of Adafruit CircuitPython for your board.

Next you'll need to install the necessary libraries to use the hardware--carefully follow the steps to find and install these libraries from Adafruit's CircuitPython library bundle.  Our introduction guide has a great page on how to install the library bundle for both express and non-express boards.

Remember for non-express boards like the, you'll need to manually install the necessary libraries from the bundle:

  • adafruit_bus_device
  • adafruit_esp32_spi
  • adafruit_requests
  • neopixel

Before continuing make sure your board's lib folder or root filesystem has the above files copied over.

Next connect to the board's serial REPL so you are at the CircuitPython >>> prompt.

Into your lib folder. Once that's done, load up the following example using Mu or your favorite editor:

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# SPDX-FileCopyrightText: 2019 ladyada for Adafruit Industries
# SPDX-License-Identifier: MIT

import board
import busio
from digitalio import DigitalInOut
import adafruit_requests as requests
import adafruit_esp32spi.adafruit_esp32spi_socket as socket
from adafruit_esp32spi import adafruit_esp32spi

# Get wifi details and more from a secrets.py file
try:
    from secrets import secrets
except ImportError:
    print("WiFi secrets are kept in secrets.py, please add them there!")
    raise

print("ESP32 SPI webclient test")

TEXT_URL = "http://wifitest.adafruit.com/testwifi/index.html"
JSON_URL = "http://api.coindesk.com/v1/bpi/currentprice/USD.json"


# If you are using a board with pre-defined ESP32 Pins:
esp32_cs = DigitalInOut(board.ESP_CS)
esp32_ready = DigitalInOut(board.ESP_BUSY)
esp32_reset = DigitalInOut(board.ESP_RESET)

# If you have an AirLift Shield:
# esp32_cs = DigitalInOut(board.D10)
# esp32_ready = DigitalInOut(board.D7)
# esp32_reset = DigitalInOut(board.D5)

# If you have an AirLift Featherwing or ItsyBitsy Airlift:
# esp32_cs = DigitalInOut(board.D13)
# esp32_ready = DigitalInOut(board.D11)
# esp32_reset = DigitalInOut(board.D12)

# If you have an externally connected ESP32:
# NOTE: You may need to change the pins to reflect your wiring
# esp32_cs = DigitalInOut(board.D9)
# esp32_ready = DigitalInOut(board.D10)
# esp32_reset = DigitalInOut(board.D5)

spi = busio.SPI(board.SCK, board.MOSI, board.MISO)
esp = adafruit_esp32spi.ESP_SPIcontrol(spi, esp32_cs, esp32_ready, esp32_reset)

requests.set_socket(socket, esp)

if esp.status == adafruit_esp32spi.WL_IDLE_STATUS:
    print("ESP32 found and in idle mode")
print("Firmware vers.", esp.firmware_version)
print("MAC addr:", [hex(i) for i in esp.MAC_address])

for ap in esp.scan_networks():
    print("\t%s\t\tRSSI: %d" % (str(ap["ssid"], "utf-8"), ap["rssi"]))

print("Connecting to AP...")
while not esp.is_connected:
    try:
        esp.connect_AP(secrets["ssid"], secrets["password"])
    except OSError as e:
        print("could not connect to AP, retrying: ", e)
        continue
print("Connected to", str(esp.ssid, "utf-8"), "\tRSSI:", esp.rssi)
print("My IP address is", esp.pretty_ip(esp.ip_address))
print(
    "IP lookup adafruit.com: %s" % esp.pretty_ip(esp.get_host_by_name("adafruit.com"))
)
print("Ping google.com: %d ms" % esp.ping("google.com"))

# esp._debug = True
print("Fetching text from", TEXT_URL)
r = requests.get(TEXT_URL)
print("-" * 40)
print(r.text)
print("-" * 40)
r.close()

print()
print("Fetching json from", JSON_URL)
r = requests.get(JSON_URL)
print("-" * 40)
print(r.json())
print("-" * 40)
r.close()

print("Done!")
View on GitHub

And save it to your board, with the name code.py. 

You may need to change the esp32_cs, esp32_ready and esp32_reset pins in the code to match your hardware's pinout.

Then go down to this line

esp.connect_AP(b'MY_SSID_NAME', b'MY_SSID_PASSWORD')

and change MY_SSID_NAME and MY_SSID_PASSWORD to your access point name and password, keeping them within the '' quotes. (This example doesn't use the secrets' file, but its also very stand-alone so if other things seem to not work you can always re-load this. You should get something like the following:

circuitpython_image.png

In order, the example code...

Initializes the ESP32 over SPI using the SPI port and 3 control pins:

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esp32_cs = DigitalInOut(board.ESP_CS)
esp32_ready = DigitalInOut(board.ESP_BUSY)
esp32_reset = DigitalInOut(board.ESP_RESET)

spi = busio.SPI(board.SCK, board.MOSI, board.MISO)
esp = adafruit_esp32spi.ESP_SPIcontrol(spi, esp32_cs, esp32_ready, esp32_reset)

Tells our requests library the type of socket we're using (socket type varies by connectivity type - we'll be using the adafruit_esp32spi_socket for this example). We'll also set the interface to an esp object. This is a little bit of a hack, but it lets us use requests like CPython does.

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requests.set_socket(socket, esp)

Verifies an ESP32 is found, checks the firmware and MAC address

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if esp.status == adafruit_esp32spi.WL_IDLE_STATUS:
    print("ESP32 found and in idle mode")
print("Firmware vers.", esp.firmware_version)
print("MAC addr:", [hex(i) for i in esp.MAC_address])

Performs a scan of all access points it can see and prints out the name and signal strength:

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for ap in esp.scan_networks():
    print("\t%s\t\tRSSI: %d" % (str(ap['ssid'], 'utf-8'), ap['rssi']))

Connects to the AP we've defined here, then prints out the local IP address, attempts to do a domain name lookup and ping google.com to check network connectivity (note sometimes the ping fails or takes a while, this isn't a big deal)

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    print("Connecting to AP...")
esp.connect_AP(b'MY_SSID_NAME', b'MY_SSID_PASSWORD')
print("Connected to", str(esp.ssid, 'utf-8'), "\tRSSI:", esp.rssi)
print("My IP address is", esp.pretty_ip(esp.ip_address))
print("IP lookup adafruit.com: %s" % esp.pretty_ip(esp.get_host_by_name("adafruit.com")))
print("Ping google.com: %d ms" % esp.ping("google.com"))

OK now we're getting to the really interesting part. With a SAMD51 or other large-RAM (well, over 32 KB) device, we can do a lot of neat tricks. Like for example we can implement an interface a lot like requests - which makes getting data really really easy

To read in all the text from a web URL call requests.get - you can pass in https URLs for SSL connectivity

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TEXT_URL = "http://wifitest.adafruit.com/testwifi/index.html"
print("Fetching text from", TEXT_URL)
r = requests.get(TEXT_URL)
print('-'*40)
print(r.text)
print('-'*40)
r.close()

Or, if the data is in structured JSON, you can get the json pre-parsed into a Python dictionary that can be easily queried or traversed. (Again, only for nRF52840, M4 and other high-RAM boards)

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JSON_URL = "http://api.coindesk.com/v1/bpi/currentprice/USD.json"
print("Fetching json from", JSON_URL)
r = requests.get(JSON_URL)
print('-'*40)
print(r.json())
print('-'*40)
r.close()

Requests

We've written a requests-like library for web interfacing named Adafruit_CircuitPython_Requests. This library allows you to send HTTP/1.1 requests without "crafting" them and provides helpful methods for parsing the response from the server.

Here's an example of using Requests to perform GET and POST requests to a server.

Download Project Bundle
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# SPDX-FileCopyrightText: 2021 ladyada for Adafruit Industries
# SPDX-License-Identifier: MIT

# adafruit_requests usage with an esp32spi_socket
import board
import busio
from digitalio import DigitalInOut
import adafruit_esp32spi.adafruit_esp32spi_socket as socket
from adafruit_esp32spi import adafruit_esp32spi
import adafruit_requests as requests

# Add a secrets.py to your filesystem that has a dictionary called secrets with "ssid" and
# "password" keys with your WiFi credentials. DO NOT share that file or commit it into Git or other
# source control.
# pylint: disable=no-name-in-module,wrong-import-order
try:
    from secrets import secrets
except ImportError:
    print("WiFi secrets are kept in secrets.py, please add them there!")
    raise

# If you are using a board with pre-defined ESP32 Pins:
esp32_cs = DigitalInOut(board.ESP_CS)
esp32_ready = DigitalInOut(board.ESP_BUSY)
esp32_reset = DigitalInOut(board.ESP_RESET)

# If you have an externally connected ESP32:
# esp32_cs = DigitalInOut(board.D9)
# esp32_ready = DigitalInOut(board.D10)
# esp32_reset = DigitalInOut(board.D5)

# If you have an AirLift Featherwing or ItsyBitsy Airlift:
# esp32_cs = DigitalInOut(board.D13)
# esp32_ready = DigitalInOut(board.D11)
# esp32_reset = DigitalInOut(board.D12)

spi = busio.SPI(board.SCK, board.MOSI, board.MISO)
esp = adafruit_esp32spi.ESP_SPIcontrol(spi, esp32_cs, esp32_ready, esp32_reset)

print("Connecting to AP...")
while not esp.is_connected:
    try:
        esp.connect_AP(secrets["ssid"], secrets["password"])
    except RuntimeError as e:
        print("could not connect to AP, retrying: ", e)
        continue
print("Connected to", str(esp.ssid, "utf-8"), "\tRSSI:", esp.rssi)

# Initialize a requests object with a socket and esp32spi interface
socket.set_interface(esp)
requests.set_socket(socket, esp)

TEXT_URL = "http://wifitest.adafruit.com/testwifi/index.html"
JSON_GET_URL = "https://httpbin.org/get"
JSON_POST_URL = "https://httpbin.org/post"

print("Fetching text from %s" % TEXT_URL)
response = requests.get(TEXT_URL)
print("-" * 40)

print("Text Response: ", response.text)
print("-" * 40)
response.close()

print("Fetching JSON data from %s" % JSON_GET_URL)
response = requests.get(JSON_GET_URL)
print("-" * 40)

print("JSON Response: ", response.json())
print("-" * 40)
response.close()

data = "31F"
print("POSTing data to {0}: {1}".format(JSON_POST_URL, data))
response = requests.post(JSON_POST_URL, data=data)
print("-" * 40)

json_resp = response.json()
# Parse out the 'data' key from json_resp dict.
print("Data received from server:", json_resp["data"])
print("-" * 40)
response.close()

json_data = {"Date": "July 25, 2019"}
print("POSTing data to {0}: {1}".format(JSON_POST_URL, json_data))
response = requests.post(JSON_POST_URL, json=json_data)
print("-" * 40)

json_resp = response.json()
# Parse out the 'json' key from json_resp dict.
print("JSON Data received from server:", json_resp["json"])
print("-" * 40)
response.close()
View on GitHub

The code first sets up the ESP32SPI interface. Then, it initializes a request object using an ESP32 socket and the esp object.

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import board
import busio
from digitalio import DigitalInOut
import adafruit_esp32spi.adafruit_esp32spi_socket as socket
from adafruit_esp32spi import adafruit_esp32spi
import adafruit_requests as requests

# If you have an externally connected ESP32:
esp32_cs = DigitalInOut(board.D9)
esp32_ready = DigitalInOut(board.D10)
esp32_reset = DigitalInOut(board.D5)

spi = busio.SPI(board.SCK, board.MOSI, board.MISO)
esp = adafruit_esp32spi.ESP_SPIcontrol(spi, esp32_cs, esp32_ready, esp32_reset)

print("Connecting to AP...")
while not esp.is_connected:
    try:
        esp.connect_AP(b'MY_SSID_NAME', b'MY_SSID_PASSWORD')
    except RuntimeError as e:
        print("could not connect to AP, retrying: ",e)
        continue
print("Connected to", str(esp.ssid, 'utf-8'), "\tRSSI:", esp.rssi)

# Initialize a requests object with a socket and esp32spi interface
requests.set_socket(socket, esp)

Make sure to set the ESP32 pinout to match your AirLift breakout's connection:

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esp32_cs = DigitalInOut(board.D9)
esp32_ready = DigitalInOut(board.D10)
esp32_reset = DigitalInOut(board.D5)

HTTP GET with Requests

The code makes a HTTP GET request to Adafruit's WiFi testing website - http://wifitest.adafruit.com/testwifi/index.html.

To do this, we'll pass the URL into requests.get(). We're also going to save the response from the server into a variable named response.

While we requested data from the server, we'd what the server responded with. Since we already saved the server's response, we can read it back. Luckily for us, requests automatically decodes the server's response into human-readable text, you can read it back by calling response.text.

Lastly, we'll perform a bit of cleanup by calling response.close(). This closes, deletes, and collect's the response's data. 

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    print("Fetching text from %s"%TEXT_URL)
response = requests.get(TEXT_URL)
print('-'*40)

print("Text Response: ", response.text)
print('-'*40)
response.close()

While some servers respond with text, some respond with json-formatted data consisting of attribute–value pairs.

CircuitPython_Requests can convert a JSON-formatted response from a server into a CPython dict. object.

We can also fetch and parse json data. We'll send a HTTP get to a url we know returns a json-formatted response (instead of text data). 

Then, the code calls response.json() to convert the response to a CPython dict. 

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    print("Fetching JSON data from %s"%JSON_GET_URL)
response = requests.get(JSON_GET_URL)
print('-'*40)

print("JSON Response: ", response.json())
print('-'*40)
response.close()

HTTP POST with Requests

Requests can also POST data to a server by calling the requests.post method, passing it a data value.

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data = '31F'
print("POSTing data to {0}: {1}".format(JSON_POST_URL, data))
response = requests.post(JSON_POST_URL, data=data)
print('-'*40)

json_resp = response.json()
# Parse out the 'data' key from json_resp dict.
print("Data received from server:", json_resp['data'])
print('-'*40)
response.close()

You can also post json-formatted data to a server by passing json data into the requests.post method.

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json_data = {"Date" : "July 25, 2019"}
print("POSTing data to {0}: {1}".format(JSON_POST_URL, json_data))
response = requests.post(JSON_POST_URL, json=json_data)
print('-'*40)

json_resp = response.json()
# Parse out the 'json' key from json_resp dict.
print("JSON Data received from server:", json_resp['json'])
print('-'*40)
response.close()

Advanced Requests Usage

Want to send custom HTTP headers, parse the response as raw bytes, or handle a response's http status code in your CircuitPython code?

We've written an example to show advanced usage of the requests module below.

Download Project Bundle
Copy Code 
# SPDX-FileCopyrightText: 2021 ladyada for Adafruit Industries
# SPDX-License-Identifier: MIT

import board
import busio
from digitalio import DigitalInOut
import adafruit_esp32spi.adafruit_esp32spi_socket as socket
from adafruit_esp32spi import adafruit_esp32spi
import adafruit_requests as requests

# Add a secrets.py to your filesystem that has a dictionary called secrets with "ssid" and
# "password" keys with your WiFi credentials. DO NOT share that file or commit it into Git or other
# source control.
# pylint: disable=no-name-in-module,wrong-import-order
try:
    from secrets import secrets
except ImportError:
    print("WiFi secrets are kept in secrets.py, please add them there!")
    raise

# If you are using a board with pre-defined ESP32 Pins:
esp32_cs = DigitalInOut(board.ESP_CS)
esp32_ready = DigitalInOut(board.ESP_BUSY)
esp32_reset = DigitalInOut(board.ESP_RESET)

# If you have an externally connected ESP32:
# esp32_cs = DigitalInOut(board.D9)
# esp32_ready = DigitalInOut(board.D10)
# esp32_reset = DigitalInOut(board.D5)

spi = busio.SPI(board.SCK, board.MOSI, board.MISO)
esp = adafruit_esp32spi.ESP_SPIcontrol(spi, esp32_cs, esp32_ready, esp32_reset)

print("Connecting to AP...")
while not esp.is_connected:
    try:
        esp.connect_AP(secrets["ssid"], secrets["password"])
    except RuntimeError as e:
        print("could not connect to AP, retrying: ", e)
        continue
print("Connected to", str(esp.ssid, "utf-8"), "\tRSSI:", esp.rssi)

# Initialize a requests object with a socket and esp32spi interface
socket.set_interface(esp)
requests.set_socket(socket, esp)

JSON_GET_URL = "http://httpbin.org/get"

# Define a custom header as a dict.
headers = {"user-agent": "blinka/1.0.0"}

print("Fetching JSON data from %s..." % JSON_GET_URL)
response = requests.get(JSON_GET_URL, headers=headers)
print("-" * 60)

json_data = response.json()
headers = json_data["headers"]
print("Response's Custom User-Agent Header: {0}".format(headers["User-Agent"]))
print("-" * 60)

# Read Response's HTTP status code
print("Response HTTP Status Code: ", response.status_code)
print("-" * 60)

# Close, delete and collect the response data
response.close()
View on GitHub

WiFi Manager

That simpletest example works but its a little finicky - you need to constantly check WiFi status and have many loops to manage connections and disconnections. For more advanced uses, we recommend using the WiFiManager object. It will wrap the connection/status/requests loop for you - reconnecting if WiFi drops, resetting the ESP32 if it gets into a bad state, etc.

Here's a more advanced example that shows the WiFi manager and also how to POST data with some extra headers:

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Copy Code 
# SPDX-FileCopyrightText: 2019 ladyada for Adafruit Industries
# SPDX-License-Identifier: MIT

import time
import board
import busio
from digitalio import DigitalInOut
import neopixel
from adafruit_esp32spi import adafruit_esp32spi
from adafruit_esp32spi import adafruit_esp32spi_wifimanager

print("ESP32 SPI webclient test")

# Get wifi details and more from a secrets.py file
try:
    from secrets import secrets
except ImportError:
    print("WiFi secrets are kept in secrets.py, please add them there!")
    raise

# If you are using a board with pre-defined ESP32 Pins:
esp32_cs = DigitalInOut(board.ESP_CS)
esp32_ready = DigitalInOut(board.ESP_BUSY)
esp32_reset = DigitalInOut(board.ESP_RESET)

# If you have an externally connected ESP32:
# esp32_cs = DigitalInOut(board.D9)
# esp32_ready = DigitalInOut(board.D10)
# esp32_reset = DigitalInOut(board.D5)

spi = busio.SPI(board.SCK, board.MOSI, board.MISO)
esp = adafruit_esp32spi.ESP_SPIcontrol(spi, esp32_cs, esp32_ready, esp32_reset)
"""Use below for Most Boards"""
status_light = neopixel.NeoPixel(
    board.NEOPIXEL, 1, brightness=0.2
)  # Uncomment for Most Boards
"""Uncomment below for ItsyBitsy M4"""
# status_light = dotstar.DotStar(board.APA102_SCK, board.APA102_MOSI, 1, brightness=0.2)
# Uncomment below for an externally defined RGB LED
# import adafruit_rgbled
# from adafruit_esp32spi import PWMOut
# RED_LED = PWMOut.PWMOut(esp, 26)
# GREEN_LED = PWMOut.PWMOut(esp, 27)
# BLUE_LED = PWMOut.PWMOut(esp, 25)
# status_light = adafruit_rgbled.RGBLED(RED_LED, BLUE_LED, GREEN_LED)
wifi = adafruit_esp32spi_wifimanager.ESPSPI_WiFiManager(esp, secrets, status_light)

counter = 0

while True:
    try:
        print("Posting data...", end="")
        data = counter
        feed = "test"
        payload = {"value": data}
        response = wifi.post(
            "https://io.adafruit.com/api/v2/"
            + secrets["aio_username"]
            + "/feeds/"
            + feed
            + "/data",
            json=payload,
            headers={"X-AIO-KEY": secrets["aio_key"]},
        )
        print(response.json())
        response.close()
        counter = counter + 1
        print("OK")
    except OSError as e:
        print("Failed to get data, retrying\n", e)
        wifi.reset()
        continue
    response = None
    time.sleep(15)
View on GitHub

You'll note here we use a secrets.py file to manage our SSID info. The wifimanager is given the ESP32 object, secrets and a neopixel for status indication.

Note, you'll need to add a some additional information to your secrets file so that the code can query the Adafruit IO API:

  • aio_username
  • aio_key

You can go to your adafruit.io View AIO Key link to get those two values and add them to the secrets file, which will now look something like this:

Download File
Copy Code 
# This file is where you keep secret settings, passwords, and tokens!
# If you put them in the code you risk committing that info or sharing it

secrets = {
    'ssid' : '_your_ssid_',
    'password' : '_your_wifi_password_',
    'timezone' : "America/Los_Angeles", # http://worldtimeapi.org/timezones
    'aio_username' : '_your_aio_username_',
    'aio_key' : '_your_aio_key_',
    }

Next, set up an Adafruit IO feed named test

We can then have a simple loop for posting data to Adafruit IO without having to deal with connecting or initializing the hardware!

Take a look at your test feed on Adafruit.io and you'll see the value increase each time the CircuitPython board posts data to it!

circuitpython_feedstest.jpg

CircuitPython BLE

CircuitPython BLE UART Example

It's easy to use Adafruit AirLift ESP32 co-processor boards for Bluetooth Low Energy (BLE) with CircuitPython. When you reset the ESP32, you can put it in WiFi mode (the default), or in BLE mode; you cannot use both modes simultaneously.

Here's a simple example of using BLE to connect CircuitPython with the Bluefruit Connect app. Use CircuitPython 6.0.0 or later.

Note: Don't confuse the ESP32 with the ESP32-S2, which is a different module with a similar name. The ESP32-S2 does not support BLE.

Currently, AirLift BLE support is not currently available on boards with Espressif chips. If the Espressif board provides _bleio, it is for native BLE support (e.g. ESP32-S3), not AirLift.
Currently the AirLift support for CircuitPython only provides BLE peripheral support. BLE central is under development. So you cannot connect to BLE devices like Heart Rate monitors, etc., but you can act as a BLE peripheral yourself.

Adafruit AirLift ESP32 Shield Wiring

If you have an Adafruit AirLift ESP32 Shield, you will need to solder three jumpers closed on the bottom side of the board to enable BLE. The rest of the ESP32 pins you need are already jumpered to certain shield pins.

Update the AirLift Firmware

You will need to update the AirLift's firmware to at least version 1.7.1. Previous versions of the AirLift firmware do not support BLE. 

Follow the instructions in the guide below, and come back to this page when you've upgraded the AirLift's firmware:

Ensure the AirLift firmware is version 1.7.1 or higher for BLE to work.

Install CircuitPython Libraries

First make sure you are running the latest version of Adafruit CircuitPython for your board.

Next you'll need to install the necessary libraries to use the hardware. Thankfully, we can do this in one go. In the example below, click the Download Project Bundle button below to download the necessary libraries and the code.py file in a zip file. Extract the contents of the zip file, and copy the entire lib folder and the code.py file to your CIRCUITPY drive.

Your CIRCUITPY/lib folder should contain the following folders and files:

  • /adafruit_airlift
  • /adafruit_ble
  • /adafruit_bus_device
  • /adafruit_esp32spi
  • adafruit_requests.mpy
CIRCUITPY

Install the Adafruit Bluefruit LE Connect App

The Adafruit Bluefruit LE Connect iOS and Android apps allow you to connect to BLE peripherals that provide a over-the-air "UART" service. Follow the instructions in the Bluefruit LE Connect Guide to download and install the app on your phone or tablet.

BLE Example

TAKE NOTE: Adjust the program as needed to suit the AirLift board you have. Comment and uncomment lines 19-55 below as necessary.
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# SPDX-FileCopyrightText: 2020 Dan Halbert, written for Adafruit Industries
#
# SPDX-License-Identifier: Unlicense

# pylint: disable=unused-import
import board
import busio
from digitalio import DigitalInOut
from adafruit_ble import BLERadio
from adafruit_ble.advertising.standard import ProvideServicesAdvertisement
from adafruit_ble.services.nordic import UARTService
from adafruit_esp32spi import adafruit_esp32spi
from adafruit_airlift.esp32 import ESP32

# If you are using a Metro M4 Airlift Lite, PyPortal,
# or MatrixPortal, you can use the default pin settings.
# Leave this DEFAULT line uncommented.
# If you are using a board with pre-defined ESP32 Pins:
esp32 = ESP32()

# If you are using a Metro M7 **OR**
# if you are using CircuitPython 6.0.0 or earlier,
# on PyPortal and PyPortal Titano only, use the pin settings
# below. Comment out the DEFAULT line above and uncomment
# the line below. For CircuitPython 6.1.0, the pin names
# have changed for these boards, and the DEFAULT line
# above is correct.
# esp32 = ESP32(tx=board.TX, rx=board.RX)

# If you are using an AirLift FeatherWing or AirLift Bitsy Add-On,
# use the pin settings below. Comment out the DEFAULT line above
# and uncomment the lines below.
# If you are using an AirLift Breakout, check that these
# choices match the wiring to your microcontroller board,
# or change them as appropriate.
# esp32 = ESP32(
#     reset=board.D12,
#     gpio0=board.D10,
#     busy=board.D11,
#     chip_select=board.D13,
#     tx=board.TX,
#     rx=board.RX,
# )

# If you are using an AirLift Shield,
# use the pin settings below. Comment out the DEFAULT line above
# and uncomment the lines below.
# esp32 = ESP32(
#     reset=board.D5,
#     gpio0=board.D6,
#     busy=board.D7,
#     chip_select=board.D10,
#     tx=board.TX,
#     rx=board.RX,
# )

adapter = esp32.start_bluetooth()

ble = BLERadio(adapter)
uart = UARTService()
advertisement = ProvideServicesAdvertisement(uart)

while True:
    ble.start_advertising(advertisement)
    print("waiting to connect")
    while not ble.connected:
        pass
    print("connected: trying to read input")
    while ble.connected:
        # Returns b'' if nothing was read.
        one_byte = uart.read(1)
        if one_byte:
            print(one_byte)
            uart.write(one_byte)
View on GitHub

Talk to the AirLift via the Bluefruit LE Connect App

Start the Bluefruit LE Connect App on your phone or tablet. You should see a CIRCUITPY device available to connect to. Tap the Connect button (1):

adafruit_products_airlift-connect.png

You'll then see a list of Bluefruit Connect functions ("modules"). Choose the UART module (2):

adafruit_products_airlift-uart.png

On the UART module page, you can type a string and press Send (3). You'll see that string entered, and then see it echoed back (echoing is in gray).

adafruit_products_airlift-echo.png

Arduino WiFi

You can use an AirLift with Arduino. Unlike CircuitPython, it will work with just about any Arduino board, even a classic Arduino UNO. However, if you want to use libraries like Adafruit IO Arduino, ArduinoJSON, or add sensors and SD card, you'll really want an ATSAMD21 (Cortex M0) or ATSAMD51 (Cortex M4), both of which have plenty or RAM.

Library Install

We're using a variant of the Arduino WiFiNINA library, which is amazing and written by the Arduino team! The official WiFi101 library won't work because it doesn't support the ability to change the pins.

So! We made a fork that you can install.

Click here to download the library:

Within the Arduino IDE, select Sketch->Include Library -> Add .ZIP library...

adafruit_products_image.png

And select the zip you just downloaded.

First Test

OK now you have it wired and library installed, time to test it out!

Lets start by scanning the local networks. Load up the ScanNetworks example

adafruit_products_image.png

At the top you'll see a section where the GPIO pins are defined

adafruit_products_image.png

If you don't see this, you may have the wrong WiFiNINA library installed. Uninstall it and re-install the Adafruit one as above.

Arduino Microcontroller Pin Definition

Next, you'll need to need to modify the pin definition above for the AirLift Shield. Replace the configuration in the sketch with the pinouts below:

Download File
Copy Code 
#define SPIWIFI       SPI  // The SPI port
#define SPIWIFI_SS    10   // Chip select pin
#define ESP32_RESETN  5    // Reset pin
#define SPIWIFI_ACK   7    // a.k.a BUSY or READY pin
#define ESP32_GPIO0   6

Compile and upload to your board wired up to the AirLift

adafruit_products_image.png

If you don't even get the MAC address printed out, check your wiring.

If you get the MAC address but cannot scan any networks, check your power supply. You need a solid 3-5VDC into Vin in order for the ESP32 not to brown out.

WiFi Connection Test

Now that you have your wiring checked, time to connect to the Internet!

Open up the WiFiWebClient example

adafruit_products_image.png

Open up the secondary tab, arduino_secrets.h. This is where you will store private data like the SSID/password to your network.

adafruit_products_image.png

You must change these string values before updating to your board!

After you've set it correctly, upload and check the serial monitor. You should see the following. If not, go back, check wiring, power and your SSID/password

adafruit_products_image.png

Secure Connection Example

Many servers today do not allow non-SSL connectivity. Lucky for you the ESP32 has a great TLS/SSL stack so you can have that all taken care of for you. Here's an example of a secure WiFi connection:

adafruit_products_image.png

Note we use WiFiSSLClient client; instead of WiFiClient client; to require an SSL connection!

adafruit_products_image.png

JSON Parsing Example

This example is a little more advanced - many sites will have API's that give you JSON data. We'll use ArduinoJSON to convert that to a format we can use and then display that data on the serial port (which can then be re-directed to a display of some sort)

First up, use the Library manager to install ArduinoJSON.

Then load the example JSONdemo

adafruit_products_image.png

By default it will connect to to the Twitter banner image API, parse the username and followers and display them.

adafruit_products_image.png

Adapting Other Examples

Once you've got it connecting to the Internet you can check out the other examples. The only change you'll want to make is at the top of the sketches, add:

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Copy Code 
#define SPIWIFI       SPI  // The SPI port
#define SPIWIFI_SS    10   // Chip select pin
#define ESP32_RESETN  5    // Reset pin
#define SPIWIFI_ACK   7    // a.k.a BUSY or READY pin
#define ESP32_GPIO0   6

And then before you check the status() of the module, call the function WiFi.setPins(SPIWIFI_SS, SPIWIFI_ACK, ESP32_RESETN, ESP32_GPIO0, &SPIWIFI); like so:

Download File
Copy Code 
// check for the WiFi module:
  WiFi.setPins(SPIWIFI_SS, SPIWIFI_ACK, ESP32_RESETN, ESP32_GPIO0, &SPIWIFI);
  while (WiFi.status() == WL_NO_MODULE) {
    Serial.println("Communication with WiFi module failed!");
    // don't continue
    delay(1000);
  }

Downloads

This guide was first published on Jun 21, 2019. It was last updated on Mar 17, 2021.