CalmFold

UIST 2026 Student Innovation Contest

EmotiBit EDA-Triggered Two-Motor System

Skip to step 5 if system is already setup

This project uses live EmotiBit EDA data to detect an increase in physiological arousal and activate two DC micromotors simultaneously through a DRV8833 dual motor driver.

This README assumes the EmotiBit has already been set up and can stream data using the official EmotiBit Getting Started guide. The EmotiBit and host computer must be on the same Wi-Fi network.

Hardware

• EmotiBit + compatible Feather
• Adafruit DRV8833 dual motor driver
• 2× Vybronics VZ4SL2A0000003 DC micromotors
• Male-to-female jumper wires
• EmotiBit battery
• Computer running EmotiBit Oscilloscope and Python

Motor: https://www.digikey.com/en/products/detail/vybronics-inc/VZ4SL2A0000003/7732312

Files

Use these two files:

EmotiBit_stock_firmware_two_motors.ino
emotibit_eda_two_motors.py

The Python script receives live EDA, detects an increase relative to the user's recent baseline, ignores invalid EDA readings of 10000 or higher, and sends a UDP motor command to the EmotiBit.

Wiring

Each motor uses a separate DRV8833 output channel.

EmotiBit Feather          DRV8833

GPIO 16  ──────────────── AIN1
    └──────────────────── BIN1

GPIO 17  ──────────────── AIN2
    └──────────────────── BIN2

GND      ──────────────── GND

Motor connections:

DRV8833              Motor

AOUT1 ───────────── Motor 1 wire 1
AOUT2 ───────────── Motor 1 wire 2

BOUT1 ───────────── Motor 2 wire 1
BOUT2 ───────────── Motor 2 wire 2

GPIO 16 controls both AIN1 and BIN1, while GPIO 17 controls both AIN2 and BIN2. This causes both DRV8833 channels to receive the same command, so both motors run simultaneously.

Male-to-female jumper wires were used for the Feather-to-DRV8833 connections.

If one motor spins in the wrong physical direction, reverse that motor's two output wires.

1. Upload the Modified EmotiBit Firmware

Use:

EmotiBit_stock_firmware_two_motors.ino

This firmware preserves normal EmotiBit operation while adding UDP motor control.

The important settings are:

const int MOTOR_IN1 = 16;
const int MOTOR_IN2 = 17;

const unsigned long MOTOR_DURATION_MS = 1000;
const uint16_t MOTOR_UDP_PORT = 4210;

When the firmware receives M, both motors run for 1 second. When it receives S, both motors stop.

After uploading, open the serial monitor. Once Wi-Fi connects, the firmware prints something similar to:

Motor UDP listener started at 172.20.10.7:4210

Record the IP address.

2. Configure EmotiBit Oscilloscope

Connect to the EmotiBit and start streaming data.

In EmotiBit Oscilloscope, make sure OSC Data is checked so the live EDA data is forwarded to the Python script.

OSC Data:    CHECKED
OSC address: /EmotiBit/0/EDA
IP:          127.0.0.1
Port:        12345

If OSC Data is not checked, the Python script will not receive EDA measurements.

3. Install Python Dependencies

pip install numpy python-osc

4. Configure the Python Script

Open:

emotibit_eda_two_motors.py

Change:

MOTOR_IP = "172.20.10.7"

to the IP address printed by your EmotiBit.

The remaining communication settings should be:

OSC_IP = "127.0.0.1"
OSC_PORT = 12345
EDA_ADDRESS = "/EmotiBit/0/EDA"

MOTOR_PORT = 4210

5. Position the EDA Sensor

Before running the detector, put on the EmotiBit and make sure the EDA electrodes are flush against the skin with consistent contact.

Poor or intermittent skin contact can make the initial baseline unreliable.

Once the sensor is positioned correctly, keep the placement consistent during calibration and use.

6. Run and Calibrate

Make sure:

1. The EmotiBit is streaming data.
2. OSC Data is checked in EmotiBit Oscilloscope.
3. The EDA electrodes are flush against the skin.
4. The Python script contains the correct EmotiBit IP address.

Then run:

python3 emotibit_eda_two_motors.py

The detector first collects approximately 22 seconds of data:

20 s baseline + 2 s recent window

During this period:

Calibrating: ...

will appear in the terminal.

Keep the EDA sensor flush against the skin and remain relatively still during calibration. Avoid adjusting the EmotiBit or electrodes until calibration is complete, since changes in electrode contact can cause large changes in the EDA signal.

After calibration, the script continuously compares the newest EDA data against the previous baseline.

EDA Trigger

The final detection settings are:

BASELINE_SECONDS = 20
RECENT_SECONDS = 2

Z_THRESHOLD = 2.5
MIN_EDA_CHANGE = 0.005
REQUIRED_CONSECUTIVE_SAMPLES = 8

COOLDOWN_SECONDS = 15

A motor activation occurs when the recent EDA level:

1. increases by at least 0.005,
2. is at least 2.5 baseline standard deviations above baseline, and
3. remains above the threshold for 8 consecutive samples.

When triggered, Python sends M to the EmotiBit over UDP, and both motors activate simultaneously for one second.

The 15 s cooldown prevents repeated activations from the same sustained EDA increase.

System Flow

EDA electrodes
[flush with skin]
      │
      ▼
   EmotiBit
      │
      │ Wi-Fi
      ▼
EmotiBit Oscilloscope
[OSC Data checked]
      │
      │ /EmotiBit/0/EDA
      ▼
Python EDA detector
      │
      │ UDP "M"
      ▼
EmotiBit Feather
      │
 GPIO 16 / 17
      ▼
    DRV8833
   ┌────┴────┐
   ▼         ▼
Motor 1    Motor 2

Troubleshooting

Python receives no EDA: make sure the EmotiBit is streaming and OSC Data is checked in EmotiBit Oscilloscope.

EDA is streaming but motors do not run: verify MOTOR_IP matches the IP printed by the EmotiBit, both devices are on the same Wi-Fi network, and both the firmware and Python script use UDP port 4210.

Only one motor runs: check that Motor 1 is on AOUT1/AOUT2 and Motor 2 is on BOUT1/BOUT2, and verify GPIO 16 reaches both AIN1/BIN1 and GPIO 17 reaches both AIN2/BIN2.

EDA displays 10000: the Python script ignores values at or above 10000 so they do not falsely trigger the motors.

Need a longer motor activation: change:

const unsigned long MOTOR_DURATION_MS = 1000;

For example, 2000 runs the motors for two seconds. Re-upload the firmware after changing it.