How do I solve XIAO's abnormal interference and the sensor's abysmal abnormal output?

Before did not contact hardware, I am this respect rookie :disappointed_relieved:

Problem description

  1. When there is no sensor signal output, the value of output by the XIAO microcontroller ranges from 10 to 500. How to eliminate interference and reach the desired output of 0 to 30?
  2. When XIAO microcontroller is connected to the sensor signal output pin, the interference is amplified to tens of thousands of abnormal value output, how to solve it?

Detailed description:

Output of sensor not connected the XIAO:

The XIAO microcontroller is connected to the 3.3V power supply pin of ESP32, and the output is 20~400. I change the power supply of notebook to the power supply of battery power for the ESP32, and the problem remains the same.

I try to do:

  1. Measured with a digital multimeter, the power supply pin of the ESP32 development board is about 1.6~3.7V, occasionally up to 5V (maybe my positive and negative probes are not accurate).

  2. Check XIAO’s ADC using ADC pin to GND pin for any problems with

simple code

void setup() {
void loop() {
  int sensorValue = analogRead(A0);

OUT print:

  1. The microcontroller XIAO connects the TTL to USB power supply pin, but the output is still abnormal.


  1. If unplug the DUpont wires of the ADC PIN and GND PIN and plug them back in, the following will happen(Using simple Code)


Abnormal sensor output

The sensor power supply is connected to the battery (3.3V, 1A current), the sensor output pin is connected to each analog input pin of the microcontroller, and the output value is about tens of thousands.


I try to do:

Seeeduino Xiao’s manual mentioned that the analog pin can accept the input of 0~3.3V, and did not specify the upper limit of current. I tried to connect the power supply of the sensor to the power supply pin of the development board.


The result is the same, seems to have nothing to do with the current size… After unplugging the signal output line of the sensor, the microcontroller is not connected to the signal line of any sensor… As shown above.


Asked the store, customer service said this is not normal, the sensor should output the value of 0~500, if the sensor monitors the current output of 300~400, not monitoring the general output of 0~30 range.

Normal output:

Equipment information

XIAO EMG sampled code: EMG.ino · GitHub

Sensor parameters: {ED0056}干电极肌肉电传感器 · 语雀

Microcontrollers XIAO general description: Getting Started with Seeeduino XIAO - Seeed Wiki

Microcontrollers XIAO instruction manual:


How do I solve XIAO’s abnormal interference and the sensor’s abysmal abnormal output?