Project 11 XGO Listens to Sounds

Ⅰ. Teaching Aims

1. Read the on-board microphone sound level(0-100, refresh approximately each 20 ms).

2. Use single/double threshold(s) to enable XGO to switch emojis or actions based on the sound volume.

3. Build a simple “rest when quiet / forage when noisy” model.

Ⅱ. Pre-class Check

• XGO + Foxbit + MicroBlocks IDE.

• XGO battery power ≥ 60 %. Place the robot on a flat ground.

• MicroBlocks status bar shows a green dot, XGO-lite extension is loaded and the development board model is Foxbit.

• The background noise in the classroom should be maintained at 5 - 15 to avoid continuous high noise from the outside.

Ⅲ. Key Blocks Analysis

Functions	Return 0 – 100 ambient volume
Fallible points	Forgot to put it in forever for real-time reading
Functions	Perform actions based on the threshold
Fallible points	Too small threshold interval → jitter
Functions	Stand up, sit down, slide, etc
Fallible points	Volume jitter causes repeated actions
Functions	Emojis on LED dot matrix
Fallible points	Not added wait → flash
Functions	Eliminate jitter / delay
Fallible points	It’s too short to display stably

Reference value of sound level:

Scenes	Typical readings
Quiet classroom	5 – 15
Normal speaking environment	20 – 35
A round of handclap	45 – 60
Loud shouting	70 – 90

Ⅳ. Practice

Test 1: “Sound Volume → Emoji”

Logic:

• Volume > 50 → yes for 0.5 s

• Otherwise, no

Online code: Click here

Test 2: “Rest When Quiet / Forage When Noisy”

Logic

• Volume > 50 → Hunt for food + happy, for 2 s

• Otherwise, slightly squat down: slide body Z by 10 mm + sad

Online code: Click here

Ⅴ. Quiz

1. What would happen if we changed wait 500 in Test 1 to 50 ms?

2. Why does Test 2 use the mode variable instead of simply if…else?

3. If you want the volume to be louder and the steps to be wider, how should you use map()? Please write down the parameters.

Ⅵ. FAQ

Questions	Possible causes	Solutions
Emoji flashes	The volume jitter near the threshold	Increase the threshold interval; wait ≥ 200 ms
Repeated actions	There are no state variables.	Import mode and delay after switching
Sluggish switching between rest and foraging	The background noise is high, or the threshold is too far	Adjust the threshold; Perform the moving average
The microphone reading is always high	The sensor is affected by wind noise, or apply a film	Block the wind; Make sure the microphone hole is exposed
Large sliding amplitude	slide body distance exceeds limit	Maintain within ± 15 mm