Leonardo + serial adapter · Dual PC

Download Knife.Baby from Downloads, sign in and choose your game. Select Dual PC → Leonardo.

Temporarily plug the Leonardo into your second PC. When Knife.Baby asks, press RESET once. Keep it plugged in until the firmware has been written and checked.

Disconnect power before wiring. Use a compatible CP2102, CH340, FT232 or CH343 USB-to-serial adapter and three jumper wires. Wire colours do not matter. TX and RX may be labelled TXD and RXD.

• Adapter TX / TXD → Leonardo RX, pin 0 (RX◄0).
• Adapter RX / RXD → Leonardo TX, pin 1 (TX►1).
• Adapter GND → Leonardo GND, for example beside pin 13.

Connect only TX, RX and GND. Leave 5V, 3V3, VCC, V_MCU, DTR, RTS and CTS unconnected. The gaming PC powers the Leonardo through USB.

Use an adapter with signal levels compatible with the Leonardo. If your module’s switch controls UART logic voltage, use the required 5V-compatible setting. A switch labelled 5V/3.3V can control only the power output on some modules; check that module’s documentation rather than relying on the chip name alone.

1. Move the Leonardo’s micro-USB cable to the gaming PC.
2. Connect the serial adapter’s USB plug to the second PC.
3. Let Windows install the adapter driver. If Device Manager shows a warning, install the driver for the adapter’s chip from its manufacturer: CP210x, CH340, CH343 or FT232.
4. Knife.Baby should discover the adapter automatically. The sidebar board card may show a name such as CP2102 · COM5 and changes to Connected after the board responds.

Install the capture software

On your gaming PC, install the versions specified for this setup:

• OBS Studio 31.1.0
• DistroAV 6.0.0
• NDI 6 Runtime, from the DistroAV installation instructions

If you need to replace an existing OBS installation, back up your profiles and scenes first. These are the setup versions in this guide; check Knife.Baby’s release notes before changing them.

Capture the game

1. Add a Game Capture source for your game. Use Game Capture rather than Display Capture.
2. Right-click the source → Transform → Reset Transform.
3. Choose Transform → Center to Screen. Do not use Fit to Screen for this setup.

Set the video format

Open Settings → Video:

• Base (Canvas) Resolution: your Knife.Baby scan size, for example 640 × 640.
• Output (Scaled) Resolution: the same scan size.
• If different games use different scan sizes, use the largest required size.
• FPS: Fractional FPS Value → 240 / 1 to start, if your PCs and network can sustain it.

Open Settings → Advanced:

• Process Priority: High
• Color Format: NV12
• Color Space: Rec. 709
• Color Range: Limited

Send the stream

Open Tools → DistroAV NDI Settings:

• Turn Main Output on.
• Name the output Knife.Baby.
• Leave Preview Output off.

Turn off the OBS preview, run OBS as administrator, and connect both PCs by Ethernet to the same router.

Keep the highest frame rate that stays smooth. Watch the stream stutter reading in Knife.Baby’s Overview. If stutter stays high, lower OBS to 144 / 1, then lower it further if needed. A stable stream is more useful than an unstable high frame rate.

If OBS locks the Video settings, turn DistroAV’s Main Output off, change the settings, then turn it on again.

Back on your second PC, the final Knife.Baby setup step should find the stream named Knife.Baby. Check the received size and frame rate.

If discovery fails, choose Can’t find it? and enter the gaming PC’s IP address. Allow OBS and Knife.Baby through Windows Firewall for your private network.

Plug your mouse into the second PC. To control the gaming PC, enable Passthrough on the board card or press F7. Some laptops require Fn + F7. Press it again to return mouse control to the second PC.

Test Passthrough with the board’s mouse-output USB connection plugged into the gaming PC. If its output loops back into the same PC running Knife.Baby, cursor movement can freeze. Press F7 again to leave Passthrough.