Once you've finished setting up your Feather ESP32-S2 Reverse TFT with CircuitPython, you can access the code and necessary libraries by downloading the Project Bundle.
To do this, click on the Download Project Bundle button in the window below. It will download to your computer as a zipped folder.
# SPDX-FileCopyrightText: 2024 Liz Clark for Adafruit Industries
# SPDX-License-Identifier: MIT
import ssl
import os
import socketpool
import wifi
import board
import digitalio
import displayio
import vectorio
from adafruit_bitmap_font import bitmap_font
from adafruit_display_text import bitmap_label
import adafruit_imageload
from adafruit_io.adafruit_io import IO_HTTP, AdafruitIO_RequestError
import adafruit_max1704x
import adafruit_requests
from simpleio import map_range
from adafruit_ticks import ticks_ms, ticks_add, ticks_diff
# states
send_io = True
bat_clock = ticks_ms()
bat_timer = 60 * 1000
first_run = True
# settings.toml imports
aio_username = os.getenv('AIO_USERNAME')
aio_key = os.getenv('AIO_KEY')
# connect to wifi
wifi.radio.connect(os.getenv('CIRCUITPY_WIFI_SSID'), os.getenv('CIRCUITPY_WIFI_PASSWORD'))
pool = socketpool.SocketPool(wifi.radio)
requests = adafruit_requests.Session(pool, ssl.create_default_context())
io = IO_HTTP(aio_username, aio_key, requests)
try:
# get feed
battery_feed = io.get_feed("battery-monitor")
except AdafruitIO_RequestError:
# if no feed exists, create one
battery_feed = io.create_new_feed("battery-monitor")
# default group
group = displayio.Group()
# text only group
textOnly_group = displayio.Group()
board.DISPLAY.root_group = group
# palette for vector graphics
palette = displayio.Palette(5)
palette[0] = 0xFF0000
palette[1] = 0xFFFF00
palette[2] = 0x00FF00
palette[3] = 0x0000FF
palette[4] = 0x000000
# battery rectangle
rect = vectorio.Rectangle(pixel_shader=palette, width=72, height=45, x=140, y=70, color_index = 0)
group.append(rect)
text_bg = vectorio.Rectangle(pixel_shader=palette, width=115, height=70,
x=120, y=60, color_index = 4)
# io indicator circle
circle = vectorio.Circle(pixel_shader=palette, radius=8, x=10, y=10, color_index=3)
textOnly_group.append(circle)
# graphics bitmap
bitmap, palette_bit = adafruit_imageload.load(
"/bat_bg.bmp",
bitmap=displayio.Bitmap,
palette=displayio.Palette,
)
# purple is made transparent
palette_bit.make_transparent(0)
tile_grid = displayio.TileGrid(bitmap, pixel_shader=palette_bit)
group.append(tile_grid)
group.append(circle)
# font for graphics
sm_file = "/roundedHeavy-26.bdf"
sm_font = bitmap_font.load_font(sm_file)
# font for text only
lg_file = "/roundedHeavy-46.bdf"
lg_font = bitmap_font.load_font(lg_file)
volt_text = bitmap_label.Label(sm_font, text=" V", x=150, y=33)
group.append(volt_text)
big_volt_text = bitmap_label.Label(lg_font, text=" V")
big_volt_text.anchor_point = (0.5, 0.0)
big_volt_text.anchored_position = (board.DISPLAY.width / 2, 0)
textOnly_group.append(big_volt_text)
percent_text = bitmap_label.Label(sm_font, text=" %", x=150, y=90)
big_percent_text = bitmap_label.Label(lg_font, text=" %", x=board.DISPLAY.width//2, y=90)
big_percent_text.anchor_point = (0.5, 1.0)
big_percent_text.anchored_position = (board.DISPLAY.width / 2, board.DISPLAY.height - 15)
textOnly_group.append(big_percent_text)
# buttons
button0 = digitalio.DigitalInOut(board.D0)
button0.direction = digitalio.Direction.INPUT
button0.pull = digitalio.Pull.UP
button0_state = False
button1 = digitalio.DigitalInOut(board.D1)
button1.direction = digitalio.Direction.INPUT
button1.pull = digitalio.Pull.DOWN
button1_state = False
button2 = digitalio.DigitalInOut(board.D2)
button2.direction = digitalio.Direction.INPUT
button2.pull = digitalio.Pull.DOWN
button2_state = False
# MAX17048 instantiation
monitor = adafruit_max1704x.MAX17048(board.I2C())
monitor.activity_threshold = 0.01
# colors for battery graphic
def get_color(value):
if value < 30:
return 0
elif 30 <= value <= 75:
return 1
else:
return 2
while True:
# reset button state on release
if button0.value and button0_state:
button0_state = False
if not button1.value and button1_state:
button1_state = False
if not button2.value and button2_state:
button2_state = False
# toggle sending to adafruit io
if not button0.value and not button0_state:
button0_state = True
send_io = not send_io
if send_io:
circle.color_index = 3
else:
circle.color_index = 4
# toggle graphics or text only
if button1.value and not button1_state:
button1_state = True
if board.DISPLAY.root_group == group:
board.DISPLAY.root_group = textOnly_group
else:
board.DISPLAY.root_group = group
# toggle battery graphic or % text
if button2.value and not button2_state:
button2_state = True
if len(group) > 4:
group.pop()
group.pop()
else:
group.append(text_bg)
group.append(percent_text)
# read MAX17048 every 60 seconds
if first_run or ticks_diff(ticks_ms(), bat_clock) >= bat_timer:
first_run = False
battery_volts = monitor.cell_voltage
battery_percent = monitor.cell_percent
print(f"Battery voltage: {battery_volts:.2f} Volts")
print(f"Battery percentage: {battery_percent:.1f} %")
print()
battery_display = map_range(battery_percent, 0, 100, 0, 72)
battery_x = map_range(battery_percent, 0, 100, 210, 140)
# update rectangle to reflect battery charge
rect.width = int(battery_display)
rect.x = int(battery_x)
rect.color_index = get_color(battery_percent)
volt_text.text = f"{battery_volts:.2f} V"
percent_text.text = f"{battery_percent:.1f} %"
big_volt_text.text = f"{battery_volts:.2f} V"
big_percent_text.text = f"{battery_percent:.1f} %"
if battery_percent >= 100 and send_io:
io.send_data(battery_feed["key"], battery_percent)
bat_clock = ticks_add(bat_clock, bat_timer)
Upload the Code and Libraries to the Feather ESP32-S2 Reverse TFT
After downloading the Project Bundle, plug your Feather ESP32-S2 Reverse TFT into the computer's USB port with a known good USB data+power cable. You should see a new flash drive appear in the computer's File Explorer or Finder (depending on your operating system) called CIRCUITPY. Unzip the folder and copy the following items to the Feather's CIRCUITPY drive:
- lib folder
- code.py
- bat_bg.bmp
- roundedHeavy-26.bdf
- roundedHeavy-46.bdf
Your Feather ESP32-S2 Reverse TFT CIRCUITPY drive should look like this after copying the lib folder, .bdf font files, .bmp image file and the code.py file.
Add Your settings.toml File
As of CircuitPython 8.0.0, there is support for Environment Variables. Environment variables are stored in a settings.toml file. Similar to secrets.py, the settings.toml file separates your sensitive information from your main code.py file. Add your settings.toml file as described in the Create Your settings.toml File page earlier in this guide. You'll need to include your WiFi network SSID and password as CIRCUITPY_WIFI_SSID and CIRCUITPY_WIFI_PASSWORD and your Adafruit IO username and key as AIO_USERNAME and AIO_KEY.
CIRCUITPY_WIFI_SSID = "YOUR-SSID-HERE" CIRCUITPY_WIFI_PASSWORD = "YOUR-SSID-PASSWORD-HERE" AIO_USERNAME = "YOUR-AIO-USERNAME-HERE" AIO_KEY = "YOUR-AIO-KEY-HERE"
How the CircuitPython Code Works
At the top of the code are some states that are used in the loop. send_io enables sending the battery charging data to Adafruit IO. bat_timer is the amount of time that the battery monitor is checked and first_run and used to note that the code is running for the first time in the loop.
# states send_io = True bat_clock = ticks_ms() bat_timer = 60 * 1000 first_run = True
After the states are the settings.toml imports and WiFi and Adafruit IO connections.
# settings.toml imports
aio_username = os.getenv('AIO_USERNAME')
aio_key = os.getenv('AIO_KEY')
# connect to wifi
wifi.radio.connect(os.getenv('CIRCUITPY_WIFI_SSID'), os.getenv('CIRCUITPY_WIFI_PASSWORD'))
pool = socketpool.SocketPool(wifi.radio)
requests = adafruit_requests.Session(pool, ssl.create_default_context())
io = IO_HTTP(aio_username, aio_key, requests)
try:
# get feed
battery_feed = io.get_feed("battery-monitor")
except AdafruitIO_RequestError:
# if no feed exists, create one
battery_feed = io.create_new_feed("battery-monitor")
If your WiFi access point name or password are incorrect, an error will be generated.
Graphics
Next are the graphics. There are two display groups: one that includes graphical elements and one that is text only. You can switch between then in the loop depending on your preferences. the bat_bg bitmap file is loaded using the adafruit_image library and its background color is made transparent. vectorio shapes are used to show the battery charge graphic and if you are sending data to Adafruit IO.
# default group
group = displayio.Group()
# text only group
textOnly_group = displayio.Group()
board.DISPLAY.root_group = group
# palette for vector graphics
palette = displayio.Palette(5)
palette[0] = 0xFF0000
palette[1] = 0xFFFF00
palette[2] = 0x00FF00
palette[3] = 0x0000FF
palette[4] = 0x000000
# battery rectangle
rect = vectorio.Rectangle(pixel_shader=palette, width=72, height=45, x=140, y=70, color_index = 0)
group.append(rect)
text_bg = vectorio.Rectangle(pixel_shader=palette, width=115, height=70,
x=120, y=60, color_index = 4)
# io indicator circle
circle = vectorio.Circle(pixel_shader=palette, radius=8, x=10, y=10, color_index=3)
textOnly_group.append(circle)
# graphics bitmap
bitmap, palette_bit = adafruit_imageload.load(
"/bat_bg.bmp",
bitmap=displayio.Bitmap,
palette=displayio.Palette,
)
# purple is made transparent
palette_bit.make_transparent(0)
tile_grid = displayio.TileGrid(bitmap, pixel_shader=palette_bit)
group.append(tile_grid)
group.append(circle)
Then all of the text attributes are created. There are two font files, one for a smaller font and one for a larger font. The larger font is used for the text only graphics group.
# font for graphics sm_file = "/roundedHeavy-26.bdf" sm_font = bitmap_font.load_font(sm_file) # font for text only lg_file = "/roundedHeavy-46.bdf" lg_font = bitmap_font.load_font(lg_file) volt_text = bitmap_label.Label(sm_font, text=" V", x=150, y=33) group.append(volt_text) big_volt_text = bitmap_label.Label(lg_font, text=" V") big_volt_text.anchor_point = (0.5, 0.0) big_volt_text.anchored_position = (board.DISPLAY.width / 2, 0) textOnly_group.append(big_volt_text) percent_text = bitmap_label.Label(sm_font, text=" %", x=150, y=90) big_percent_text = bitmap_label.Label(lg_font, text=" %", x=board.DISPLAY.width//2, y=90) big_percent_text.anchor_point = (0.5, 1.0) big_percent_text.anchored_position = (board.DISPLAY.width / 2, board.DISPLAY.height - 15) textOnly_group.append(big_percent_text)
Buttons and I2C
The three buttons on the Feather are setup as digitalio inputs. The onboard MAX17048 is instantiated over I2C.
# buttons button0 = digitalio.DigitalInOut(board.D0) button0.direction = digitalio.Direction.INPUT button0.pull = digitalio.Pull.UP button0_state = False button1 = digitalio.DigitalInOut(board.D1) button1.direction = digitalio.Direction.INPUT button1.pull = digitalio.Pull.DOWN button1_state = False button2 = digitalio.DigitalInOut(board.D2) button2.direction = digitalio.Direction.INPUT button2.pull = digitalio.Pull.DOWN button2_state = False # MAX17048 instantiation monitor = adafruit_max1704x.MAX17048(board.I2C()) monitor.activity_threshold = 0.01
Colors
There is a simple function called get_color() that maps the charge percentage of the battery to a color in a palette. This changes the color of the battery from red to yellow to green as it charges up.
# colors for battery graphic
def get_color(value):
if value < 30:
return 0
elif 30 <= value <= 75:
return 1
else:
return 2
The Loop
In the loop, the buttons control the UI appearance and code functionality. Button D0 toggles sending the battery info to Adafruit IO. Button D1 changes between the text only display group and the graphical group. Button D2 changes between representing the battery charge percentage in text or via the battery graphic.
# toggle sending to adafruit io
if not button0.value and not button0_state:
button0_state = True
send_io = not send_io
if send_io:
circle.color_index = 3
else:
circle.color_index = 4
# toggle graphics or text only
if button1.value and not button1_state:
button1_state = True
if board.DISPLAY.root_group == group:
board.DISPLAY.root_group = textOnly_group
else:
board.DISPLAY.root_group = group
# toggle battery graphic or % text
if button2.value and not button2_state:
button2_state = True
if len(group) > 4:
group.pop()
group.pop()
else:
group.append(text_bg)
group.append(percent_text)
Monitor the Battery
Every minute the MAX17048 is read to check on the battery voltage and charge percentage. The graphics are updated with the data to show on the TFT. If you chose to send the data to IO, the charge percentage is sent to your feed when the battery is fully charged.
# read MAX17048 every 60 seconds
if first_run or ticks_diff(ticks_ms(), bat_clock) >= bat_timer:
first_run = False
battery_volts = monitor.cell_voltage
battery_percent = monitor.cell_percent
print(f"Battery voltage: {battery_volts:.2f} Volts")
print(f"Battery percentage: {battery_percent:.1f} %")
print()
battery_display = map_range(battery_percent, 0, 100, 0, 72)
battery_x = map_range(battery_percent, 0, 100, 210, 140)
# update rectangle to reflect battery charge
rect.width = int(battery_display)
rect.x = int(battery_x)
rect.color_index = get_color(battery_percent)
volt_text.text = f"{battery_volts:.2f} V"
percent_text.text = f"{battery_percent:.1f} %"
big_volt_text.text = f"{battery_volts:.2f} V"
big_percent_text.text = f"{battery_percent:.1f} %"
if battery_percent >= 100 and send_io:
io.send_data(battery_feed["key"], battery_percent)
bat_clock = ticks_add(bat_clock, bat_timer)
Page last edited January 22, 2025
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