*\* = Should we survey Tomorrow Forum to help decide?*
### Analog sticks
TMR tech under consideration + to be evaluated.

Reasons for TMR: TMR does not incur stick drift over time. Lower power draw than hall effect.

Stick position (distance from knuckle & relative to natural thumb position)

> Top surface diameter?
 Quest 3 `12.8mm`
 Index `13.4mm`
 PS5 Dualsense `17.4mm`
 Switch 2 Pro `17.3mm`
 Switch 2 Joycon `17.4mm`

> Top surface distance from controller surface?
 Quest 3 `6.8mm`
 Index `7.4mm`
 PS5 Dualsense `8.8mm`
 Switch 2 Pro `9.2mm`
 Switch 2 Joycon `6.4mm`

### Face buttons
Silicone membrane as the commonly accepted standard. All agreed that we should stick to this style.

> Button size?
 Quest 3, PS5 Dualsense `10mm`
 Index `9mm`
 Switch 2 Pro `11.3mm`
 Switch 2 Joycon `8.3mm`

> Button travel?
 Quest 3 `1mm`
 Index `1.5mm`
 PS5 Dualsense `1.3mm`
 Switch 2 Pro `1mm`
 Switch 2 Joycon `0.6mm`
 
- *longer travel = more tiring to repeat*
- *shallower travel = faster action. needs stronger tactile response*

### Trigger button
Needs to be analog.

Do we make it dual stage?*\** Index has this, and the click at the end of travel is where a mouse click event happens (i.e. in a desktop overlay). The rest of the travel is largely used for hand expressiveness. In some games it dictates the pressure or power of an action.

Opinions for reference: I am personally indifferent. Ville likes the distinctive click of dual stage.

### Grip button
Also analog.

**Problem acknowledgment:** Quest controllers are prone to false positives with games' "grip" event. It is easy to fully depress this button with the first middle finger segment, without fully wrapping the finger around the controller.

**Approaches considered for improvement:**
A. Copy Steam Frame and make the grip button dual-stage, like the Index trigger.
B. Move the analog element closer to the base of the finger. Add a capacitive "grip action" pad where the fingertip lands.

### Capacitive sensing
Considerations:
- On the face buttons
- On the analog stick
- On the trigger
- Beneath the grip button for ring and pinky fingers
- In the thumb rest area (for thumb down gesture w/no risk of accidental input)
All of the above are used for social VR. Two core use cases: Emotive face puppeting, and sign language.

Additionally, Quest 3 has capacitive sensing under the palm near the index finger. We suspect this exists to reject button activation/battery drain while controller is loose in a bag.

### Battery
Require AA out of the box. Spring-loaded battery terminals at both ends.

Consider offering a rechargeable battery addon.

USB-C port should exist on each controller for fast firmware updates. Can double as a charge port with above accessory.

*Note: Wired firmware updates will also be ideal for prototyping phase.*

### Safety strap
Tether point at bottom

Do we want wrist loop (Quest)?

Do we want back-of-hand strap (Index, Frame)? *Requires additional tether point near top of controller*.

### LED
Singular status LED for pairing, low battery, charging, updating, active.

Consider it to double as an aesthetic LED a la Beyond HMD LED—some translucent portion of controller? Possible inspiration from Dualsense, Gamesir Cyclone 2

### "Pro tracking" extensibility
Consider how and where a magnetic field tracking extension could ingress and connect.

### Haptics
Single linear resonant actuator (LRA)
--> the fine frequency control can double for creating beep sounds, i.e. for on and off. Index controllers do this.

### HMD ↔ controller features
Pairing process (headset listening, button combo on controller)

Battery charge level comms --> thru to SteamVR

Controller FW version number

SteamVR **ON** when controller connects

Headset --> controllers comms:
- Turn off command
- Relay haptics (strength/frequency/duration)
- Turn *on* command?
- Potential LED control
- Wireless firmware update