ros2_iio_medical

ROS 2 bridge between Linux IIO biosignal kernel drivers and ROS 2 topics, targeting medical robotics and surgical monitoring applications.

Covers the full acquisition stack — from analog sensor through Linux kernel driver, IIO subsystem, and DMA ring buffer, up to typed ROS 2 topics ready for robot control, ML inference, and clinical logging.

Supported Devices

Chip	Signal	Channels	Topic
TI ADS1299	EEG / ECG	8 × 24-bit	/biosignal/eeg
ADI MAX86150	ECG + PPG	2	/biosignal/ecg_ppg
TI ti-ads1298	ECG	8 × 24-bit	/biosignal/ecg
ADI MAX30102	SpO₂ / heart-rate	2	/biosignal/spo2

Any Linux IIO device with standard sysfs or triggered-buffer interface is supported.

Acquisition Modes

Polling bridge — iio_bridge

Reads in_voltageX_raw from sysfs on a ROS 2 wall timer. Simple, no kernel buffer setup required. Good for prototyping and low-rate sensors.

ros2 launch ros2_iio_medical iio_bridge.launch.py

Triggered buffer bridge — iio_triggered_bridge

Uses the Linux IIO kernel buffer with epoll(7). The hardware DRDY interrupt drives the ADC; the kernel fills a DMA ring buffer; epoll_wait() wakes the acquisition thread exactly once per sample batch. No timer jitter. No missed samples. Correct approach for continuous EEG/ECG.

ros2 launch ros2_iio_medical iio_triggered_bridge.launch.py

Build

cd ~/ros2_ws
source /opt/ros/humble/setup.bash
colcon build --packages-select ros2_iio_medical
source install/setup.bash

Test without hardware

A simulator script creates a fake ADS1299 IIO sysfs tree at /tmp/iio_sim so the bridge can be exercised without physical hardware:

# Terminal 1 — start simulator (250 Hz synthetic EEG/ECG)
bash src/ros2_iio_medical/test/simulate_ads1299.sh &

# Terminal 2 — run bridge against fake sysfs
ros2 run ros2_iio_medical iio_bridge \
  --ros-args \
  -p device_path:=/tmp/iio_sim/iio:device0 \
  -p num_channels:=8 \
  -p sample_rate_hz:=10.0 \
  -p topic_name:=/biosignal/eeg

# Terminal 3 — verify output
ros2 topic echo /biosignal/eeg

Parameters

iio_bridge

Parameter	Default	Description
device_path	/sys/bus/iio/devices/iio:device0	IIO sysfs path
num_channels	8	Number of channels
sample_rate_hz	250.0	Polling rate
topic_name	/biosignal/ecg	Output topic

iio_triggered_bridge

Parameter	Default	Description
sysfs_path	/sys/bus/iio/devices/iio:device0	IIO sysfs path
dev_path	/dev/iio:device0	IIO character device
num_channels	8	Number of channels
buffer_length	64	Kernel buffer depth in samples
topic_name	/biosignal/eeg	Output topic

Related kernel driver work

This package is the userspace counterpart to upstream Linux IIO driver contributions for the same devices:

• ADS1299 — 24-bit 8-channel EEG/ECG ADC, new driver under upstream review
• MAX86150 — ECG + PPG analog front-end, new driver under upstream review
• ti-ads1298 — ECG ADC, fixes merged to mainline Linux

The IIO subsystem presents each device through a uniform sysfs and character device interface; this bridge reads that interface without any device-specific code, so it works with any compliant IIO driver.

License

Apache-2.0 — see LICENSE.