The haptic feedback of the Magic Trackpad 2 is configurable via three bytes.

In iFixit's teardown, we can see the that the haptic module of the Magic Trackpad 2 contains four coils. How do they map to the three config bytes?

While there is a driver for the Magic Trackpad 2 in the Linux kernel, it does not allow to configure its force feedback. That's why I installed an alternative driver. There are other approaches, but this works well enough for me.

According to this issue comment, these are the values that MacOS uses. I've also included the pressure sensitivity from here.

• strength: low
  • click: 0x15, 0x04, 0x04
  • release: 0x10, 0x00, 0x00
• strength: medium
  • click: 0x17, 0x06, 0x06
    • pressure: 0x40
  • release: 0x14, 0x00, 0x00
    • pressure: 0x26
• strength: high
  • click: 0x1E, 0x08, 0x08
  • release: 0x18, 0x02, 0x02

• single nonzero
  • 0x00, 0x00, 0x00
    • nothing
  • 0x20, 0x00, 0x00
    • a dull, soft, “deep” click
    • low-pitched
  • 0x00, 0x80, 0x00
    • a more audible, shallower “click”
    • high-pitched
  • 0x00, 0x00, 0x80
    • a more audible, shallower “clack”
    • middle-pitched
• combined
  • …

→ It boils down to 0x{low}, 0x{high}, 0x{mid}. The higher the value, the stronger the feedback.

Notation: 0x{click}, 0x{release}

• 0x10, 0x00
  • The release is not registered. Unusable.
• 0x10, 0x01
  • Very lightweight.
  • There is some pressure left when the release is registered, but really not a lot.
• 0x03, 0x01
  • One can move the cursor without clicking, somewhat.
• 0x30, 0x01
  • The click feels normal, but it feels like the touchpad “sticks” to ones finger.
• …