Stream two analog input channels from an ADS1115 ADC to a PC via Lab Streaming Layer (LSL).

This project streams two analog channels sampled by an ADS1115 (I²C, 16-bit ADC) to a PC using LSL.

Hardware required:

• ADS1115 breakout board (Adafruit)
• Arduino UNO
• USB cable

Connect the ADS1115 to the Arduino as shown:

The ADS1115 provides two differential channel pairs:

• AIN0 – AIN1
• AIN2 – AIN3

• Channel 1: Differential (AIN0 – AIN1)
• Channel 2: Single-ended with offset adjustment (via potentiometer)

If your sensor outputs 2.5 V at zero response, the potentiometer can be used to shift the baseline to 0 V at the ADC input.

You can use AIN0 and AIN2 as single-ended inputs by tying:

• AIN1 → GND
• AIN3 → GND

Refer to the ADS1115 datasheet for electrical limits.

Interfaces the ADS1115 with the PC and stream:

• 2 differential channels
• 100 Hz per channel
• Stable, timing-controlled data transmission

Designed to maintain a constant sampling interval.

Does not require the ADC.

Generates two independent sine waves (6.0Hz and 10.0Hz by default) for:

• Testing serial communication
• Verifying LSL streaming at 100Hz rate
• Evaluating signal integrity (e.g., via FFT)

You can analyze the received signal using Brain Products' BrainVision LSL Viewer.

Adjusting the input voltage Range (Gain)

Edit in ads1115-sampler:

ads.setGain(GAIN_TWO);  // ±2.048 V full-scale range

Available gain settings:

Always ensure input voltages remain within safe limits!

Adjust Sampling Rate

The ADS1115 internal data rate is configured via:

ads.setDataRate(RATE_ADS1115_250SPS);

Increasing the data rate:

• Shortens ADC conversion time
• Requires loop timing adjustment
• May cause overruns if not handled carefully

Use the debug pin output and verify timing (e.g., with an oscilloscope) if precise timing is critical.

Two receiver programs are included:

• ads1115_rx.py → Communication test tool
• ads1115_lsl → Actual LSL stream outlet

The CL input argument here is the serial port name e.g.:

python3 ads1115_lsl.py /dev/ttyACM0

Notes:

• During startup (i.e., when the Arduino resets after connecting the USB cable), a few packets may be dropped. The stream stabilizes automatically after initialization.

• The received packet interval displayed by ads1115_rx.py may occasionally show irregular intervals (e.g., alternating 8 ms / 12 ms). However, the average stream rate is correct. This behavior is related to buffering in the Arduino’s USB serial interface. Some clone Arduinos using the CH340 USB-to-serial chip perform better in this regard. Both Python receiver applications include an optional “clock recovery” mechanism to correct the received packet interval timing. To enable this fix, uncomment the indicated code section under STATE: WAIT FOR START.

• Clone Arduinos equipped with a crystal oscillator provide better timing performance.

• Sampling rate: 100 Hz per channel (default configuration)
• ADC resolution: 16-bit
• Communication: Serial (USB)
• Streaming protocol: LSL