Multiboard streaming

Stream data from multiple Red Pitaya boards simultaneously to create multi-channel acquisition and generation systems.


Overview

To stream data from multiple Red Pitaya boards simultaneously, start the streaming application on each board. This can be done either through the web interface or by loading the stream_app FPGA image and running the streaming-server command via SSH. Then either download the desktop client application or the command line client to your computer.

Both the desktop application and the command line client will detect all Red Pitaya boards on the same local network that are running the streaming application and allow for simultaneously starting and stopping the streaming process on all boards.


Key features

  • Automatic board detection: Clients automatically discover all boards on the local network

  • Synchronized control: Start and stop streaming on all boards simultaneously

  • Multi-channel acquisition: Combine channels from multiple boards (e.g., 2 boards = 4 channels, 4 boards = 8 channels)

  • Scalable system: Add more boards to increase channel count

  • Independent configuration: Each board can have different settings


Setup procedure

Step 1: Prepare Red Pitaya boards

For each Red Pitaya board in your system:

  1. Connect to the same local network using a router or network switch

    • All boards and the computer running the client must be connected to the same router or switch

    • Direct Ethernet connection between boards and computer will not work - the application requires a router or switch for automatic board detection

    • Each board will receive an IP address from the router’s DHCP server

  2. Ensure each board has a unique IP address

  3. Load the streaming application:

    • Via web interface: Open the Streaming application

    • Via SSH: Run overlay.sh stream_app && streaming-server

  4. Verify the application is running (LED 2 on, LED 0 blinking)


Step 2: Configure each board

Configure the streaming parameters for each board individually:

Note

All boards should use the same sampling rate and resolution for synchronized multi-channel acquisition.


Step 3: Install streaming client

Download and install either:

The client will automatically discover all boards running the streaming application on the local network.

Note

Ensure all boards are connected to a router and that your computer’s firewall or antivirus software allows network communication for the client application (ports 18900-18903).


Step 4: Start streaming

Using desktop client:

  1. Open the desktop application

  2. All detected boards will appear in the board list

  3. Select the boards you want to stream from

  4. Click “Start All” to begin streaming from all selected boards simultaneously

Using command line client:

The command line client can detect and stream from multiple boards automatically. See the command line client documentation for specific commands.


Hardware synchronization

For applications requiring precise timing synchronization between boards, Red Pitaya offers two hardware synchronization solutions that ensure phase-aligned data acquisition across multiple boards:

  • X-channel system - Cost-effective daisy-chain synchronization using SATA or USB-C cables. Ideal for 2-3 boards at moderate to high sampling rates.

  • X-channel 2.0 (Click Shield) synchronisation - Professional clock distribution using dedicated LVDS buffers. Recommended for larger systems (4+ boards) and maximum sampling rates.

Both systems enable synchronized multi-board acquisition for applications such as beamforming, phase-sensitive measurements, and multi-channel signal processing.

For complete hardware synchronization setup, specifications, and comparison, see the Multiboard Synchronisation documentation.

Note

Hardware synchronization is not required for basic multiboard streaming. The streaming clients can detect and control multiple boards without hardware sync, but the data acquisition will not be phase-aligned between boards.


Network considerations

For optimal multiboard streaming performance:

Router configuration

  1. Use a dedicated network switch or router (required):

    • Essential for board detection - Direct Ethernet connection will not work

    • All boards must be connected to the same router or switch for automatic discovery

    • Reduces network congestion

    • Provides stable connections

    • Enables full 1 Gbit speeds

  2. Assign static IP addresses: Prevents IP conflicts and simplifies board identification

  3. Quality of Service (QoS): If available, prioritize streaming traffic


Network bandwidth

Consider the total network bandwidth when streaming from multiple boards:

\[\text{Total bandwidth} = N_{boards} \times f_S \times N_{channels} \times Bps\]

Where:

  • \(N_{boards}\) - Number of Red Pitaya boards

  • \(f_S\) - Sampling frequency

  • \(N_{channels}\) - Number of active channels per board

  • \(Bps\) - Bytes per sample (1 for 8-bit, 2 for 16-bit)

Example: 2 boards, 62.5 MS/s, 2 channels each, 16-bit:

\[\text{Total} = 2 \times 62,500,000 \times 2 \times 2 = 500,000,000 \text{ Bytes/s} = 500 \text{ MB/s}\]

This configuration exceeds both:

  • 1 Gbit Ethernet capacity (~125 MB/s) - Network bottleneck

  • Per-board streaming limits (~62.5 MB/s per board) - See Data Streaming Limitations

In this case, you must reduce sampling rate or use fewer channels. For detailed per-board limitations and bandwidth calculations, see the Data Streaming Limitations documentation.


Performance optimization

To maximize multiboard streaming performance:

Reduce per-board data rate

  1. Lower sampling rate: Use decimation when possible

  2. Fewer channels: Disable unused channels

  3. 8-bit resolution: Use when 16-bit precision isn’t required

  4. RAW format: Skip VOLTS conversion


Optimize network

  1. Use Gigabit Ethernet: Ensure all network components support 1 Gbit or higher

  2. Quality cables: Use Cat 5e or Cat 6 cables

  3. Minimize hops: Connect boards directly to the same switch

  4. Dedicated network: Isolate streaming traffic from other network activity


Stagger streaming start

If starting all boards simultaneously causes network congestion, consider staggering the start times by a few milliseconds. This can help distribute the initial burst of data packets.

Note

This requires customizing the streaming client.


Troubleshooting

Boards not detected

Problem: Client doesn’t see all boards

Solutions:

  1. Check network topology - Boards must be connected through a router or switch. Direct Ethernet connection between computer and boards will not work

  2. Verify all boards are on the same network subnet

  3. Check firewall/antivirus settings - Ensure Python, C++ and the streaming client are allowed network access (ports 18900-18903)

    If you see errors like:

    Search: DONE
Found boards:

    or:

    Host not found
The client did not connect

    Your firewall or antivirus may be blocking network communication. Whitelist Python, C++ and the streaming client application. The easiest way to resolve this is to run the program a few times, then check the firewall/antivirus logs to see if it blocked the application, and create an exception for it (look for “Network access troubleshooting”, “Resolve blocked communication”, etc. in your security software documentation).

  4. Ensure streaming application is running on all boards (LED 2 on, LED 0 blinking)

  5. Try pinging each board from your computer

  6. Restart the streaming application on affected boards


Data loss

Problem: Packet loss or missing data from some boards

Solutions:

  1. Reduce total network bandwidth (lower sampling rate, fewer channels)

  2. Check network cable quality and connections

  3. Use a higher-quality network switch

  4. Increase block size for each board

  5. Monitor network traffic to identify bottlenecks


Use cases

4-channel acquisition (2 boards)

  • Setup: 2× STEMlab 125-14 (2 channels each)

  • Result: 4-channel synchronized acquisition

  • Example: Quadrature signal analysis, 3-phase power monitoring


8-channel acquisition (4 boards)

  • Setup: 4× STEMlab 125-14 (2 channels each)

  • Result: 8-channel synchronized acquisition

  • Example: Multi-sensor arrays, acoustic beamforming


16-channel acquisition (4× 4-input boards)

  • Setup: 4× STEMlab 125-14 4-Input (4 channels each)

  • Result: 16-channel synchronized acquisition

  • Example: Large sensor arrays, multi-channel FFT analysis


Next steps