Introduction to the ESP32-S31 with Vision: Assignment 1

Let’s blink

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In this assignment, you will create a small hardware application. The onboard RGB LED will blink red for five times and then will stay off. You can enter the provided code manually or optionally use an MCP-enabled coding assistant to generate it.

Although blinking an LED is simple, the exercise verifies three important details: the selected board, the correct GPIO, and an API that exists in its MicroPython firmware.

The ESP32-S31-Korvo-1 RGB LED

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The board has one WS2812-compatible addressable RGB LED on GPIO37. A WS2812 receives serialized color data, so treating the pin as a normal on/off GPIO does not produce a stable color.

The current ESP-Vision firmware does not include the optional MicroPython neopixel helper module. Instead, use the built-in machine.bitstream function to transmit the WS2812 waveform:

bitstream(pin, 0, (400, 850, 800, 450), data)

The timing tuple specifies the high and low periods for zero and one bits in nanoseconds. The LED expects color bytes in GRB order.

Step 1: Create the application

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Create a file named led_blink.py. You do not need an AI coding agent or MCP server to complete this assignment; you can type or copy the verified code in Step 2.

If you want to practice the optional ESP-Vision MCP workflow, ask your MCP-enabled coding assistant to generate the file with this prompt:

Use the ESP-Vision MCP server before writing code.

Target: ESP32-S31-Korvo-1 running ESP-Vision MicroPython.
Create one self-contained led_blink.py file that blinks the onboard
addressable RGB LED on GPIO37 red five times. Use only APIs verified for
esp32s31. Use machine.Pin and machine.bitstream; do not import neopixel.
Always switch the LED off in a finally block and print LED_TEST:OK only
after all five blinks complete.

The hardware, runtime, bounded behavior, cleanup, and success condition are explicit. This gives the assistant less room to make unsafe assumptions.

Step 2: Add and review the code

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Enter the following verified code. If an agent generated your script, compare its output with this structure before running it:

from machine import Pin, bitstream
import time


LED_PIN = 37
BLINKS = 5
RED = (32, 0, 0)
OFF = (0, 0, 0)
WS2812_TIMING = (400, 850, 800, 450)


def set_color(pin, color):
    red, green, blue = color
    bitstream(pin, 0, WS2812_TIMING, bytes((green, red, blue)))
    time.sleep_us(80)


def main():
    led = Pin(LED_PIN, Pin.OUT)
    try:
        for _ in range(BLINKS):
            set_color(led, RED)
            time.sleep_ms(300)
            set_color(led, OFF)
            time.sleep_ms(300)
    finally:
        set_color(led, OFF)

    print("LED_TEST:OK")


main()

RED uses a deliberately modest intensity. Full brightness is unnecessary for a status LED and can be uncomfortable to look at.

The finally block runs whether the loop completes or an exception interrupts it. It prevents the LED from remaining on after most runtime errors.

Step 3: Run and test

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1. Connect to the board in the ESP-Vision Web IDE.
2. Create led_blink.py.
3. Paste the reviewed code.
4. Save and run the script.

The LED should blink red exactly five times. The REPL should then print:

LED_TEST:OK

If the LED does not light up:

• Confirm that the target is ESP32-S31-Korvo-1.
• Confirm LED_PIN = 37.
• If you see ImportError: no module named 'neopixel', use the machine.bitstream version above rather than importing neopixel.
• Ensure that no previously flashed native ESP-IDF application is still controlling the LED.
• Reset the board and reconnect the Web IDE.

Exercise: Change the blink pattern

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Modify the program to show this sequence:

1. Red for 500 ms
2. Green for 500 ms
3. Blue for 500 ms
4. Repeat the RGB sequence three times
5. Off

Keep each RGB channel at 64 or below. Add a STATUS_TEST:OK marker after the full sequence completes.

Suggested colors:

RED = (32, 0, 0)
GREEN = (0, 32, 0)
BLUE = (0, 0, 32)

Complete working code

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from machine import Pin, bitstream
import time


LED_PIN = 37
CYCLES = 3
RED = (32, 0, 0)
GREEN = (0, 32, 0)
BLUE = (0, 0, 32)
OFF = (0, 0, 0)
WS2812_TIMING = (400, 850, 800, 450)


def set_color(pin, color):
    red, green, blue = color
    bitstream(pin, 0, WS2812_TIMING, bytes((green, red, blue)))
    time.sleep_us(80)


def main():
    led = Pin(LED_PIN, Pin.OUT)
    try:
        for _ in range(CYCLES):
            for color in (RED, GREEN, BLUE):
                set_color(led, color)
                time.sleep_ms(500)
    finally:
        set_color(led, OFF)

    print("STATUS_TEST:OK")


main()

What you learned

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In this assignment, you:

• Created the application manually or optionally with an MCP-enabled coding assistant
• Controlled the onboard WS2812-compatible LED with machine.bitstream
• Reviewed generated code for the correct pin, bounded behavior, and cleanup
• Used an observable success marker to distinguish completion from startup

Next step

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Assignment 2: Your first camera application

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