Chain Mic

MicChain is the helper class for microphone devices on the Chain bus. It provides methods to read ADC values, configure threshold values, set trigger cycle, and monitor microphone trigger events.

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UiFlow2 Example

Microphone sound detection

Open the m5core_chain_mic_basic_example.m5f2 project in UiFlow2.

This example demonstrates how to read ADC values from the Chain Mic sensor and monitor sound detection.

UiFlow2 Code Block:

Example output:

None

MicroPython Example

Microphone sound detection

This example demonstrates how to read ADC values from the Chain Mic sensor and monitor sound detection.

MicroPython Code Block:

# SPDX-FileCopyrightText: 2026 M5Stack Technology CO LTD
#
# SPDX-License-Identifier: MIT

import os, sys, io
import M5
from M5 import *
from chain import MicChain
import time
from chain import ChainBus


title0 = None
label_adc = None
label_status = None
bus2 = None
chain_mic_0 = None
last_trigger_time = None


def chain_mic_0_low_to_high_event(args):
    global title0, label_adc, label_status, bus2, chain_mic_0, last_trigger_time
    last_trigger_time = time.ticks_ms()
    label_status.setVisible(True)


def chain_mic_0_high_to_low_event(args):
    global title0, label_adc, label_status, bus2, chain_mic_0, last_trigger_time
    last_trigger_time = time.ticks_ms()
    label_status.setVisible(True)


def setup():
    global title0, label_adc, label_status, bus2, chain_mic_0, last_trigger_time

    M5.begin()
    Widgets.setRotation(1)
    Widgets.fillScreen(0x000000)
    title0 = Widgets.Title("Chain MIC Example", 3, 0xFFFFFF, 0x0000FF, Widgets.FONTS.DejaVu24)
    label_adc = Widgets.Label("ADC: --", 95, 76, 1.0, 0xFFFFFF, 0x000000, Widgets.FONTS.DejaVu24)
    label_status = Widgets.Label(
        "voice trigger", 82, 158, 1.0, 0x4CEB18, 0x000000, Widgets.FONTS.DejaVu24
    )
    bus2 = ChainBus(2, tx=21, rx=22)
    chain_mic_0 = MicChain(bus2, 1)
    chain_mic_0.set_trigger_callback(MicChain.TRIGGER_LOW_TO_HIGH, chain_mic_0_low_to_high_event)
    chain_mic_0.set_trigger_callback(MicChain.TRIGGER_HIGH_TO_LOW, chain_mic_0_high_to_low_event)
    chain_mic_0.set_trigger(True)
    chain_mic_0.set_rgb_color(0x000064)
    label_status.setVisible(False)


def loop():
    global title0, label_adc, label_status, bus2, chain_mic_0, last_trigger_time
    M5.update()
    label_adc.setText(str((str("ADC: ") + str((chain_mic_0.get_adc12())))))
    time.sleep_ms(100)
    if (time.ticks_diff((time.ticks_ms()), last_trigger_time)) > 3000:
        label_status.setVisible(False)


if __name__ == "__main__":
    try:
        setup()
        while True:
            loop()
    except (Exception, KeyboardInterrupt) as e:
        try:
            bus2.deinit()
            from utility import print_error_msg

            print_error_msg(e)
        except ImportError:
            print("please update to latest firmware")

Example output:

None

API

MicChain

class chain.mic.MicChain(bus, device_id)

Bases: KeyChain

Mic Chain class for interacting with microphone devices over Chain bus.

Parameters:

bus (ChainBus) – The Chain bus instance.
device_id (int) – The device ID of the microphone on the Chain bus.

UiFlow2 Code Block:

MicroPython Code Block:

from chain import ChainBus
from chain import MicChain

bus2 = ChainBus(2, tx=21, rx=22)
chain_mic_0 = MicChain(bus2, 1)

For other button and some general methods, please refer to the ChainKey class.

get_adc8()

Get the 8-bit ADC value of the microphone.

Returns:: 8-bit ADC value (0-255), or None if failed.
Return type:: int

UiFlow2 Code Block:

MicroPython Code Block:

value = chain_mic_0.get_adc8()

get_adc12()

Get the 12-bit ADC value of the microphone.

Returns:: 12-bit ADC value (0-4095), or None if failed.
Return type:: int

UiFlow2 Code Block:

MicroPython Code Block:

value = chain_mic_0.get_adc12()

set_trigger(enable)

Enable or disable threshold-triggered reporting.

Parameters:: enable (bool) – True to enable threshold-triggered reporting, False to disable it.
Returns:: True if the operation was successful, False otherwise.
Return type:: bool

UiFlow2 Code Block:

MicroPython Code Block:

success = chain_mic_0.set_trigger(True)

get_trigger()

Get whether threshold-triggered reporting is enabled.

Returns:: True if threshold-triggered reporting is enabled, False if disabled. Returns False if failed.
Return type:: bool

UiFlow2 Code Block:

MicroPython Code Block:

enabled = chain_mic_0.get_trigger()

set_trigger_thresh(threshold, save=False)

Set the microphone trigger threshold.

Parameters:

threshold (int) – Threshold value (0-4095).
save (bool) – Whether to save the threshold to flash. Default: False.

Returns:

True if the operation was successful, False otherwise.

Return type:

bool

UiFlow2 Code Block:

MicroPython Code Block:

success = chain_mic_0.set_trigger_thresh(2000, True)

get_trigger_thresh()

Get the microphone trigger threshold.

Returns:: Threshold value (0-4095), or None if failed.
Return type:: int

UiFlow2 Code Block:

MicroPython Code Block:

threshold = chain_mic_0.get_trigger_thresh()

set_trigger_interval(interval_ms)

Set the minimum trigger interval (debounce time).

Parameters:: interval_ms (int) – Minimum time interval between triggers in milliseconds. Range: 300-1000.
Returns:: True if the operation was successful, False otherwise.
Return type:: bool

UiFlow2 Code Block:

MicroPython Code Block:

success = chain_mic_0.set_trigger_interval(500)  # Set 500ms minimum interval between triggers

get_trigger_interval()

Get the minimum trigger interval (debounce time).

Returns:: Minimum trigger interval in milliseconds, or None if failed.
Return type:: int

UiFlow2 Code Block:

MicroPython Code Block:

interval = chain_mic_0.get_trigger_interval()

set_trigger_callback(trigger_type, callback)

Set callback for microphone trigger events.

Parameters:

trigger_type (int) – Trigger type to listen for. Use MicChain.TRIGGER_LOW_TO_HIGH (0) or MicChain.TRIGGER_HIGH_TO_LOW (1).
callback – Callback function that will be called when microphone triggers.

Return type:

None

Note

Chain related methods cannot be called in the callback function.

UiFlow2 Code Block:

MicroPython Code Block:

def mic_trigger_callback():
    print("Sound detected")

# Listen for low-to-high trigger only
chain_mic_0.set_trigger_callback(MicChain.TRIGGER_LOW_TO_HIGH, mic_trigger_callback)

# Listen for high-to-low trigger only
chain_mic_0.set_trigger_callback(MicChain.TRIGGER_HIGH_TO_LOW, mic_trigger_callback)