The Qualia ESP32-S3 can be put into deep sleep to dramatically reduce power consumption for battery-powered projects. When the display, backlight, and ESP32-S3 core are all properly shut down in the correct order, the board draws less than 1mA from a battery or dumb USB power supply.
Note: Deep sleep current cannot be measured accurately over a USB-C connection to a computer with a USB host running. The USB stack and serial REPL add significant quiescent current. Use a battery or a basic “dumb” USB power supply (with no data lines active) when measuring sleep current.
Order of Operations
Getting the backlight to actually turn off during sleep requires a specific sequence. The most common issue — the backlight staying on or turning back on when the sleep-in command is sent — is caused by the TCA9534 I/O expander having the backlight pin configured as an input rather than an output. You must explicitly reconfigure it as an output and drive it low as part of the shutdown sequence.
The correct order is:
- Send the ST7701S Sleep In command (
0x10) viaioexpander_send_init_sequence - Call
displayio.release_displays()to stop the dot clock signals from the ESP32-S3 - Reconfigure the backlight pin as an OUTPUT on the TCA9534 expander, then drive all outputs low
- Enter ESP32-S3 deep sleep with a pin alarm
Reversing steps 2 and 3, or skipping the output-register reconfiguration, will result in the backlight remaining on and current draw staying around 170–200mA.
import time
import alarm
import board
import displayio
import dotclockframebuffer
from adafruit_qualia.graphics import Graphics, Displays
# --- Display init ---
graphics = Graphics(Displays.SQUARE40_480X480, default_bg=None, auto_refresh=False)
# graphics = Graphics(Displays.SQUARE40, default_bg=None, auto_refresh=False) # 4.0" 720x720 Square (TL040HDS20)
# graphics = Graphics(Displays.SQUARE34, default_bg=None, auto_refresh=False) # 3.4" 480x480 Square (TL034WVS05)
# graphics = Graphics(Displays.ROUND21, default_bg=None, auto_refresh=False) # 2.1" 480x480 Round (TL021WVC02)
# graphics = Graphics(Displays.ROUND28, default_bg=None, auto_refresh=False) # 2.8" Round (TL028WVC01)
# graphics = Graphics(Displays.ROUND40, default_bg=None, auto_refresh=False) # 4.0" 720x720 Round (HD40015C40)
# graphics = Graphics(Displays.BAR320X820, default_bg=None, auto_refresh=False) # 3.2" 320x820 Bar (TL032FWV01)
# graphics = Graphics(Displays.BAR240X960, default_bg=None, auto_refresh=False) # 3.7" 240x960 Bar (HD371001C)
# graphics = Graphics(Displays.BAR320X960, default_bg=None, auto_refresh=False) # 4.58" 320x960 Bar (HD458002C40)
# Show display is alive for 3 seconds
graphics.display.auto_refresh = True
time.sleep(3)
graphics.display.auto_refresh = False
# --- Sleep sequence ---
i2c = graphics.i2c_bus
# Step 1: Send ST7701S Sleep In command
sleep_in = bytes([0x01, 0x10])
dotclockframebuffer.ioexpander_send_init_sequence(
i2c, sleep_in, **dict(board.TFT_IO_EXPANDER)
)
# Step 2: Release all display resources (stops dotclock signals)
displayio.release_displays()
# Step 3: Reconfigure backlight pin as OUTPUT on TCA9534, then drive all outputs LOW
while not i2c.try_lock():
pass
buf = bytearray(1)
i2c.writeto_then_readfrom(0x3F, bytes([0x03]), buf)
i2c.writeto(0x3F, bytes([0x03, buf[0] & ~(1 << board.BACKLIGHT)]))
i2c.writeto(0x3F, bytes([0x01, 0x00]))
i2c.unlock()
# Small delay to let panel settle
time.sleep(0.05)
# --- ESP32-S3 deep sleep ---
pin_alarm = alarm.pin.PinAlarm(pin=board.A0, value=False, pull=True)
print("Entering deep sleep...")
alarm.exit_and_deep_sleep_until_alarms(pin_alarm)
Page last edited April 05, 2026
Text editor powered by tinymce.
