A possible third way, given the "buttons only" constraint, would be an up/down button pair (with auto-repeat) per digit.
Up/down + left/right for selecting the digit.
Dangerous. When looking at my scope, if I hit the 10s digit +, I can go from +5v to +15v in 1 step, or the same with current if my cursor is on the wrong digit, or, I hit the wrong 'UP' button.
To move the large values, a keypad with numbers + enter, and cancel is great.
To increase and decrease voltage and current in steps, the addition of up/down arrows is also needed, but, keep those steps at a safe manageable size. Acceleration here is ok if the up/down button is held for more than 3-5 increment steps.
I prefer both the keypad + at least 1 dedicated set of up/down arrows + 1 enable/disable output button.
*Bugs Bunny voice* Imagine, asking for it
No buttons at all, make an iOS-only app that functions as input, but has no two-way comms, so the actual values are displayed on the LCD only
Whatever the case, I'd prefer rubber buttons rather than metal dome buttons.
A possible third way, given the "buttons only" constraint, would be an up/down button pair (with auto-repeat) per digit.
Up/down + left/right for selecting the digit.
Dangerous. When looking at my scope, if I hit the 10s digit +, I can go from +5v to +15v in 1 step, or the same with current if my cursor is on the wrong digit, or, I hit the wrong 'UP' button.
Agreed, but if it's really only direct entry or inc/dec then there's really no choice; direct entry by itself is useless for bench work. Digit change could be protected to some extent, e.g. long push or perhaps require an additional function button to be pressed at the same time.
With numeric keypad you can have both
Assuming the button + screen sizes are appropriate then one option is to use a 2x5 layout for buttons 0-9 that line up with the voltage and current set values.
e.g.
VV.VVV
AA.AAA
01 234
56.789
4+9 do Up/Down for the right most digit (1mV/A) and so on with a clear indication whether the keys are in Up/Down or Value Entry mode.
Don't have to faff around moving a digit selector left+right then.
That's easily fixed by a "Set" button:
- enter the value or push up/down keys
- uSupply shows the new current/voltage but keeps the old value still set
- confirm with Set key -> new value gets applied
- if not confirmed within x seconds -> update display with old value
...and then the UI is a disaster :-) fine+coarse knobs are better imo.
Why would the UI be a disaster? I think most of the supplies I work with on a daily basis work like this, and I'll take them over "Fine+coarse" any time of the day.
Good for you. But knobs are better :-)
For a PSU, a rotary encoder with momentary button (or two) will feel much more natural than any keyboard.
Remember what you can do:
- Rotate slow/fast (acceleration)
- Click
- Double Click
- Long Click
- Hold
- Rotate While held
- and even enter digits using a binary sort keyboard
I vote for encoders
i hope uSupply have + and - voltage together.
There is a reason almost every power supply with numeric keyboard also has a knob
#bringbacktheknob
It seems Dave would have to offer three models with different UIs to make everyone happy.
There is a reason almost every power supply with numeric keyboard also has a knob
#bringbacktheknob
And a knob is not necessarily an analog potentiometer, 2 gpios suffice to make an incremental rotary encoder work.
#bringbacktheknob
S 
I imagine that the usupply will be as flat and compact as possible, which would be the reason why he doesn't want knobs.
I voted for numeric entry, because that's what would make me the least mad if i had to have one or the other. however numeric + up/down would be the best. why not combine them, use another button as "shift"?
It seems Dave would have to offer three models with different UIs to make everyone happy.
There's the classic mistake of assuming that what people indicated is preferred will actually sell. You wouldn't be the first one to get hurt that way.
Assuming the button + screen sizes are appropriate then one option is to use a 2x5 layout for buttons 0-9 that line up with the voltage and current set values.
e.g.
VV.VVV
AA.AAA
01 234
56.789
4+9 do Up/Down for the right most digit (1mV/A) and so on with a clear indication whether the keys are in Up/Down or Value Entry mode.
Don't have to faff around moving a digit selector left+right then.
<enter> before and after a numeric entry, per-digit up/down ( with auto repeat), though probably not on the 10s
Or a V and an I key :
<V> 1.23<enter>
<I> 2 <enter>
To avoid needing a clear key, timeout if <enter> not pressed within a few secs - maybe pressing V or I also cancels.
completely impracticable idea here. How about a capacitive touch screen with a knob on it
that is if you are really hell bent on not using a real knob.
If this really is a binary poll then I would say a numeric keypad only.
Does uCurrent also mean micro physical size constraint for the UI?
It would be easy to include both, you can have full numeric and with a function key or a combination of 2 simultaneously keys to change to up down left right mode for digits 2,8,4,6.
So a numeric can work as up down but up down can't work as numeric.
Looking at the size and format of uSupply's LCD (53x57mm) I think we can say it wont be that flat that size of front panel would exclude encoder, so there must be other reason.
completely impracticable idea here. How about a capacitive touch screen with a knob on it that is if you are really hell bent on not using a real knob.
Every single app or device which tried to do whole "let's just emulate knob on a screen" felt utterly fucking terrible in every way. Sliders work much better for touch.
In general, yes, but that touch scroll thingy on the first iPods worked wonderfully.
Every single app or device which tried to do whole "let's just emulate knob on a screen" felt utterly fucking terrible in every way. Sliders work much better for touch.
Yes. But
sliders can be bad as well.
In general, yes, but that touch scroll thingy on the first iPods worked wonderfully.
That wasn't
emulated on a screen. It was really there.
How about a touchpad with numbers and sliders printed on the pad surface? The user could enter the voltage directly, slide the V/I, or use 'gestures' (pinch/zoom, etc.) to change output parameters.
Another possibility is the use of force-sensitive resistors, as used on some gestural-input musical instruments (Linstrument, etc.) and recently discussed on Embedded #236 (
https://www.embedded.fm/episodes/236).
A 3D-touch gestural interface on a power supply would certainly be innovative... terrible at first, probably, but innovative.
Referring to my previous post about using a printed touch-panel, here is a suggested layout:
