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 — after you signal, sunnypilot can perform the lane change; you remain responsible for checking that the maneuver is safe and permitted
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
- 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 assistance active while you control speed, acceleration, and braking manually.
On Rivian, MADS is engaged by tapping the stalk up (single tap) when MADS is enabled in sunnypilot settings.