This example uses a Feather RP2040 (although any Feather board with stemma works) and an LC709203 to track the charging of a LiPo battery with Adafruit IO.
For this project, you will need:
If the cable or battery is out of stock, you can buy any other size, although for the STEMMA QT cable, shorter is better.
Feather Setup
First, click Download Project Bundle below. This zip file will contain everything you need for this example. However, the files are also in the zip file you downloaded for the FunHouse, so you can get them from either one, just make sure you take the files from the battery_peripheral directory.
# SPDX-FileCopyrightText: 2021 Eva Herrada for Adafruit Industries
# SPDX-License-Identifier: MIT
"""
Adafruit IO connected LiPo charger.
Uses:
* https://www.adafruit.com/product/4712
* Feather board (M4 or RP2040 reccomended)
* https://www.adafruit.com/product/4264
* https://www.adafruit.com/product/2890
* https://www.adafruit.com/product/2900
Either the Feather or the Airlift Featherwing should have stacking headers for the display.
"""
from os import getenv
import time
import board
from adafruit_lc709203f import LC709203F
import busio
from digitalio import DigitalInOut
import adafruit_connection_manager
from adafruit_esp32spi import adafruit_esp32spi
from adafruit_esp32spi import adafruit_esp32spi_wifimanager
import neopixel
import adafruit_minimqtt.adafruit_minimqtt as MQTT
from adafruit_io.adafruit_io import IO_MQTT
import displayio
import i2cdisplaybus
import terminalio
from adafruit_display_text import label
import adafruit_displayio_ssd1306
# Get WiFi details and Adafruit IO keys, ensure these are setup in settings.toml
# (visit io.adafruit.com if you need to create an account, or if you need your Adafruit IO key.)
ssid = getenv("CIRCUITPY_WIFI_SSID")
password = getenv("CIRCUITPY_WIFI_PASSWORD")
aio_username = getenv("ADAFRUIT_AIO_USERNAME")
aio_key = getenv("ADAFRUIT_AIO_KEY")
if None in [ssid, password, aio_username, aio_key]:
raise RuntimeError(
"WiFi and Adafruit IO settings are kept in settings.toml, "
"please add them there. The settings file must contain "
"'CIRCUITPY_WIFI_SSID', 'CIRCUITPY_WIFI_PASSWORD', "
"'ADAFRUIT_AIO_USERNAME' and 'ADAFRUIT_AIO_KEY' at a minimum."
)
displayio.release_displays()
### WiFi ###
# If you are using a board with pre-defined ESP32 Pins:
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)
"""Use below for Most Boards"""
status_pixel = neopixel.NeoPixel(
board.NEOPIXEL, 1, brightness=0.2
) # Uncomment for Most Boards
wifi = adafruit_esp32spi_wifimanager.WiFiManager(esp, ssid, password, status_pixel=status_pixel)
# Define callback functions which will be called when certain events happen.
# pylint: disable=unused-argument
def connected(client):
client.subscribe("battery")
def subscribe(client, userdata, topic, granted_qos):
# This method is called when the client subscribes to a new feed.
print("Subscribed to {0} with QOS level {1}".format(topic, granted_qos))
def message(client, feed_id, payload):
print("Feed {0} received new value: {1}".format(feed_id, payload))
# Connect to WiFi
print("Connecting to WiFi...")
wifi.connect()
print("Connected!")
pool = adafruit_connection_manager.get_radio_socketpool(esp)
ssl_context = adafruit_connection_manager.get_radio_ssl_context(esp)
# Initialize a new MQTT Client object
mqtt_client = MQTT.MQTT(
broker="io.adafruit.com",
username=aio_username,
password=aio_key,
socket_pool=pool,
ssl_context=ssl_context,
)
# Initialize an Adafruit IO MQTT Client
io = IO_MQTT(mqtt_client)
# Connect the callback methods defined above to Adafruit IO
io.on_connect = connected
io.on_subscribe = subscribe
io.on_message = message
# Connect to Adafruit IO
print("Connecting to Adafruit IO...")
io.connect()
i2c = board.I2C() # uses board.SCL and board.SDA
# i2c = board.STEMMA_I2C() # For using the built-in STEMMA QT connector on a microcontroller
display_bus = i2cdisplaybus.I2CDisplayBus(i2c, device_address=0x3C)
WIDTH = 128
HEIGHT = 32
BORDER = 2
display = adafruit_displayio_ssd1306.SSD1306(display_bus, width=WIDTH, height=HEIGHT)
splash = displayio.Group()
display.root_group = splash
digital_label = label.Label(
terminalio.FONT, text="Battery Percent: ", color=0xFFFFFF, x=4, y=4
)
splash.append(digital_label)
alarm_label = label.Label(terminalio.FONT, text="Voltage: ", color=0xFFFFFF, x=4, y=14)
splash.append(alarm_label)
i2c = board.I2C() # uses board.SCL and board.SDA
# i2c = board.STEMMA_I2C() # For using the built-in STEMMA QT connector on a microcontroller
sensor = LC709203F(i2c)
start = 0
while True:
io.loop()
percent = sensor.cell_percent
if time.time() - start > 60:
io.publish("battery", int(percent))
start = time.time()
splash[0].text = f"Percent: {str(int(percent))}%"
splash[1].text = f"Voltage: {str(sensor.cell_voltage)}"
time.sleep(1)
The first thing you'll need to do is copy all the required libraries over. The libraries needed are:
- adafruit_esp32spi/
- adafruit_bitmap_font/
- adafruit_bus_device/
- adafruit_register.mpy
- adafruit_minimqtt/
- adafruit_io/
- adafruit_display_text/
- adafruit_lc709203f.mpy
- adafruit_requests.mpy
- neopixel.mpy
- adafruit_ticks.mpy
- adafruit_displayio_ssd1306.mpy
After you've copied over those libraries, copy code.py over to the CIRCUITPY drive.
Finally, copy settings.toml to the CIRCUITPY drive.
After you've done all that, this is what your CIRCUITPY drive should look like:
Assembly
Solder the stacking headers to either the RP2040 or the AirLift Featherwing, solder the normal headers to whichever one you didn't solder the stacking headers to and the OLED. Then, solder the headers that came with the FeatherWing Doubler to it (it's a bit easier to do if you put 2 Feather boards in to hold them in place before you get 2 pins on each header soldered).
Then, put the Feather RP2040 and AirLift FeatherWing on the doubler and put the OLED on top of the Feather.
Hook up the LiPo charger to the STEMMA QT connector on the Feather using either of the STEMMA QT connectors on the charger. Then, use the JST 2-PH cable that came with it to connect the charger to the Feather. You can use either jack on the charger.
Now that you've set everything up, plug a battery in and press the RESET button and it should look something like this:
Page last edited March 25, 2025
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