Sunnypilot & Longitudinal#
Sunnypilot is a community-supported fork of openpilot that adds longitudinal control (replacing Rivian’s ACC with openpilot’s own speed control) and MADS (steering-only mode).
Video guide: Installing Comma 3X & Longitudinal Upgrade — The Electric Valentines
Install stock openpilot first to verify your hardware setup is correct. Switch to sunnypilot once everything works.
What Longitudinal Adds#
With the Longitudinal Upgrade Kit and sunnypilot:
- openpilot controls acceleration and braking instead of Rivian’s ACC
- Set cruise speed using the steering wheel buttons
- Choose driving personality via the scroll wheel (also adjusts follow distance)
- Auto lane change with blind spot monitoring — signal and sunnypilot changes lanes when safe
Without the Longitudinal Upgrade Kit, openpilot handles steering while Rivian’s built-in ACC handles speed and braking.
Installing Sunnypilot#
- Bring the comma device inside and power it via USB-PD or laptop charger on your home WiFi
- Go to Settings → Software → Uninstall openpilot
- The device reboots
- Choose Custom Software and enter:
release.sunnypilot.ai - Connect the comma device to the Rivian and allow 1–2 minutes for registration and fingerprinting
- If the Longitudinal Upgrade Kit is installed, the comma device detects it automatically
- Enable longitudinal: Developer → openpilot Longitudinal Control (Alpha) → toggle ON
- Do NOT toggle on “Experimental Mode”
- Press the brake to turn the comma device “On Road”
- Longitudinal is working if the speed limit sign appears in the upper left corner when engaging
If the speed limit sign doesn’t appear, reboot the comma device to re-detect the hardware.
Controls Reference#
| Action | openpilot | Sunnypilot | Sunnypilot + Longitudinal |
|---|---|---|---|
| Stalk down (single tap) | Engage ACC + steering | Engage ACC + steering | Engage longitudinal + steering |
| Stalk up (single tap) | Disengage all | Engage MADS (if enabled) | Engage MADS (if enabled) |
| Steering wheel buttons | Set speed | Set speed | Set speed |
| Thumb wheel | Follow distance | Follow distance | Driving personality |
| Signal lane change | Manual | Manual | Auto with blind spot monitoring |
| Brake | Disengage all | Disengage all | Disengage all |
MADS on Rivian#
MADS (Modified Assistive Driving Safety) keeps steering active while you control speed, acceleration, and braking manually. Useful on side streets and in stop-and-go traffic.
On Rivian, MADS is engaged by tapping the stalk up (single tap) when MADS is enabled in sunnypilot settings.