uSupply Keypad Design

[David Chamberlain]

Referring to my previous post about using a printed touch-panel, here is a suggested layout:

I like the ON button being as far away as possible from the change value buttons. Also you are missing a method to select the decimal place for the up down selectors?

[BrianHG]

Referring to my previous post about using a printed touch-panel, here is a suggested layout:

I like the ON button being as far away as possible from the change value buttons. Also you are missing a method to select the decimal place for the up down selectors?

It's a generic step up/down, if you want to change the V or I by a large value, just type it in.

[JS]

How many buttons are you willing to put on the thing?

Keypad is nice, up down is a must, typing 5 digits when you want to increase 1LSD is a BUGBIG NO.

Would be nice to have a set button when you go up or down, but you should probably be able to disable it and have direct increments. If no keypad this is a must, if there is a keypad it minght not be there.

The thing very quickly ends with ton of buttons if you don't want to have multi function buttons, OVP and OVP settings, V, I, keypad, bs, incremets, set, clear, on, off. Over 20 buttons there.
NumLock might save a few, increments, OVP, OVC, and other options might be in the numbers.

JS

[Jeroen3]

No touchpad please. If a wire comes near, touch keys go ballistic. Plus if you're on an isolated workbench/chair/mat it doesn't work at all.
And there is no tactile feeling, you'd have to emulate it by clicks or beeps.

[mikerj]

No touchpad please. If a wire comes near, touch keys go ballistic. Plus if you're on an isolated workbench/chair/mat it doesn't work at all.
And there is no tactile feeling, you'd have to emulate it by clicks or beeps.

Yep, a bench instrument with capacitive touch controls is right down at the bottom of the pile in terms of usability, with proper buttons some way up and proper rotary controls at the top.

[raxpox]

How about a force sensitive resistor, like the ones used on the Linstrument and as talked about on Embedded #236?  The gesture control (slider) would be easier to implement, since that's a predominant feature of the technology.  I suspect that FSRs would have the same external voltage sensitivity issues (unless properly shielded) as capacitive touch panels, and the force required to actuate the buttons may be higher than people expect from a 'touch' device.  That said, the FSR gestural instruments seem to be very tunable to a human-range of input pressure.  Since this is a printed panel, it doesn't have to be transparent, so the dependence on ITO or other exotic materials is not required.

Regarding the button layout: I'm not a UI designer, it was just for illustrative purposes.  A button change here or there will enable the required functionality.  The point was to illustrate how a slider could be nestled in among the buttons to enable a scrolling (knob-like) function without a knob.   Personally, I prefer turning knobs over pressing buttons, since I grew up with a Tek 545 as one of my first toys, but I realize that physical knobs are not practical in a compact device.  Maybe when we're all wearing AR glasses/contact-lenses and have haptic-feedback neural implants, we can revisit the knob as an effective virtual input method.  And no 'knob' jokes, you bunch of knobs.

With respect to comments (this goes for the whole EEVBlog forum): It is much easier to come up with reasons why a technology doesn't work than it is to just try something out.  A good example is touch-screen technology in aircraft avionics - this was considered impossible for *many* reasons, until somebody implemented it, then it magically became possible.  There are HIRF/Lightning/EMC concerns with capacitive input screens, but careful engineering and understanding of the limitations will guard against 99/9% of the undesired results.  Avoiding a technology due to a 0.1% chance of false inputs is very much "putting the cart before the horse."  There are certainly boondoggle ideas out there and Dave (et al) does a good job of implementing critical thinking to prevent people from wasting money.  No worries, though - if an idea has merit, somebody will profit from it.

Thanks for the feedback, everyone.

[mikeselectricstuff]

No touchpad please. If a wire comes near, touch keys go ballistic. Plus if you're on an isolated workbench/chair/mat it doesn't work at all.
And there is no tactile feeling, you'd have to emulate it by clicks or beeps.

Yep, a bench instrument with capacitive touch controls is right down at the bottom of the pile in terms of usability, with proper buttons some way up and proper rotary controls at the top.

Yes -one reason touch buttons are a non-starter for testgear is you may well be wanting to press buttons while looking at something other than the keypad - e.g. watching for smoke, looking at other instruments.
A membrane keypad should have sufficient tactile feel ( domes on buttons or ridges between) to be able to find buttons without looking.
 

[Kalvin]

I would like to see Dave making a review of his own power supply and its ergonomics in the similar manner he has been reviewing the power supplies and their usability over the years. At least he should have a good knowledge on how *not* to design a power supply user interface and thus he should be able to avoid typical UI goof-ups.

[Maxlor]

Or maybe the whole buttons thing is something of the past. How about no buttons, but instead cellular connectivity, settings that are stored in the cloud, and a UI in a phone app? You could make the buttons configurable then to make everyone happy. You could use swiping with velocity control! And best of all, since it goes through the cloud, settings could be saved and transferred to other devices easily!

And of course, there could be different models with a price point appropriate to their functionality! Like, say, you need 1mA resolution? You can rent that feature for just $.99 a day! Data logging and graph display? Just $.19 per screen width!

 

[EEVblog]

How about a force sensitive resistor, like the ones used on the Linstrument and as talked about on Embedded #236?  The gesture control (slider) would be easier to implement, since that's a predominant feature of the technology.  I suspect that FSRs would have the same external voltage sensitivity issues (unless properly shielded) as capacitive touch panels, and the force required to actuate the buttons may be higher than people expect from a 'touch' device.  That said, the FSR gestural instruments seem to be very tunable to a human-range of input pressure.  Since this is a printed panel, it doesn't have to be transparent, so the dependence on ITO or other exotic materials is not required.

Not practical when you have say 1024 positions you need to set to precisely, and limited space. Pretty much guarantee that any such solution will suck.

[xani]

I would like to see Dave making a review of his own power supply and its ergonomics in the similar manner he has been reviewing the power supplies and their usability over the years. At least he should have a good knowledge on how *not* to design a power supply user interface and thus he should be able to avoid typical UI goof-ups.

Like lack of knob...

[Abbas]

*the feeling when you want to answer the poll but your choice is not there, what should i do!!?? *
In my opinion I would like to go with both(probably the third option  ) key for individual Voltage and Current adjust button and with separate direct numeric keypad input. It's always handy to input directly with keypad the voltage and current settings, and slightly adjust up and down when you need/feel to.

[joey120373]

Skimmed this thread, haven't voted just yet, but i like the idea of a numeric pad with UP-DOWN buttons in addition to the numeric buttons.

Of course this is an issue when it comes to adjusting the output on the fly by say +1v in .001v increments.

Velocity control would be good here, but as Mike pointed out, it could easily under/overshoot. However, ( spit balling here ) what if there were two velocity modes, one ( realtime ? ) that sets the output automatically,  and another ( Safe ? ) mode that allowed the setting(s) to be changed but the output would not be active (change) until either
A: a "set" button was pushed, or
B: a specified delay time passed, allowing the user time to correct a mistake.

Kinda spit-balling here.

One thing i haven't seen proposed is a cap-touch option ( unless this is what you were referring to raxpox ), this would allow the keypad to be directly on a PCB, and cost of extra buttons would be essentially nothing.
I'm still a fan of tactile buttons, but a cap touch PCB offers almost infinite flexibility and probably cheaper in the end vs tactile or membrane buttons ( please no membrane buttons, i hate those). 

Another approach would be an interface that could be completely customized by the user.

the Cap touch ( or whatever style ) front/switch panel could be its own system, with, say a cheep arduino compatible micro on board to either read the cap touch pads, buttons, pots or encoders . This would allow the user to write his own code, or even design his own front/switch panel. Simple Uart comms to the power supply controller. And if you don't like the design,  just roll your own  with buttons, pots, encoders,  or whatever floats your boat.
Add a port for a cheep ebay bluetooth serial interface and now you could have a remote controlled power supply...

   
 

[technix]

I like a numpad personally. It is technically downwards compatible with the up/down keys through repurposing some keys.

I don’t like a keypad with a lot of buttons though, as it can get confusing fast. Here is the keys I think is needed, with my intended layout and repurposes:

7/Home | 8/Up | 9/PgUp | Escape/Stop
4/Left | 5 (nub) | 6/Right | Fn
1/End | 2/Down | 3/PgDn | Backspace/Cancel
Period | 0/Clear | Enter/Start (bigger button)

This layout is inspired by the numpad on a PC keyboard. It is, at the same time, a numerical keypad and a navigational keypad.

The key cap of number 5 have a small nun on it for touch typing and assisting the disabled.

The Escape button is also the emergency stop button: when pressed seven times within two seconds all outputs are disabled until power cycled.

The Fn key allows other keys being further modified, like enabling a dangerous feature requires pressing Fn-Enter instead of just Enter.