This is my latest prototype.
The 16 keypad placed at the left bottom is a double action pad for function keys + numpad. Left 12 keys have double action tactile switches, Alps Alpine SKRN series. Right 4 keys have normal tactile switches. SKRN is not very durable, so I placed heavy use keys (0, comma, period, and Enter) into normal tactile switches. Double action keys are function keys for shallow press, number keys (and volume keys) for deep press. Is this a good idea? After my experience of several days, I am a bit skeptical now. I don't want to ship any wrong idea as my consumer product, so I am testing my ideas by my prototypes.
At the righit neigbour of the 16 keypad, a slider is placed. It generates two-finger swipe of Windows Precision Touchpad Protocol (PTP), i.e. it offers smooth and inertial scroll. At first, I made a slider by Cypress' IC, but I found that the scan rate (50 Hz) and resolution (8-bit) are not enough to PTP. So in this prototype, I made the slider with STM32. It gives me 100 Hz scan rate and 12-bit resolution. But I feel that the lineality is not enough. And I wish that the slider can do two-finger pintch. There is work left to do.
In the first place, is built-in slider a good idea? Now I feel that the place is wrong. In the next prototype, I will place it into the left edge of the keyboard.
I think that the iteration of prototyping is coming to an end. I will fix the final specification of my product in this year.
