EEVblog #298 - Dave's Decade Digit Display - USB Supply Part 3

[ovi_mv]

Hi

The displays that i am talking about are spares for the following NOKIA1202, NOKIA1110 and NOKIA1600.
The 1202 has the solderable type connector with SSOP pitch and 0.25mm wide pads - it can be a little tricky for hand soldering but has two 0.8mm alignment holes in the proximity of the pads that can be used for alignment.
The 1110 and 1600 have a hirose DF23-10DS (DF23C-10DS-0.5V(51) - manufacturer part number)  connector.
The 1110 & 1600 have the same pinout configuration and share some of the commands with the remark that 1600 is 4k color enabled.

All the displays work on 3.3V rail, no external negative PS is needed nor any other type of extra components - apart for the .1u cap for the LCD logic
I found the connector on Farnell and Mouser  and the price is about 0.52$ / pcs going down to 0.315$US / 1k. As a separate remark i received a price offer from Converege in february this year and they offered one reel of approx 4200 at 0.27$.pcs.

The drivers for 1110&1202 are available if necessary, the 1600 version is advanced state ongoing project.

As for the uC personally i am a big fan of LPC1114-TQFT33  if you consider the  price for 48MHz,  32K FLASH, 8K RAM is really cheap. For this project LPC 11U14 or 11U13  could be a good candidate. They have a little less RAM but has built in USB connection and USB stack and that can help specially if you want to add USB features (logging, monitoring, pram setting, etc.).
My choice for uC was also motivated by the fact that NXP teamed up with Embedded Artists and CODE RED and produced a very affordable toolchain (HW&SW) for entry level users.

Ovidiu

[EEVblog]

I think it's coming down to either:
Nokia 5110 display 84x48


or a standard 8x2 text display:


The 8x2 text display is about half the cost of the Nokia one.

Snap poll please!

Dave.

[george graves]

Now you're talking!

Even with a little 8x2 or 16x2 display you could can do some fancy stuff with the custom characters.  Like a little slow updating graphical display of the voltage/current history would be interesting.

[Uncle Vernon]

The 8x2 text display is about half the cost of the Nokia one.

Snap poll please!

Dave.

The 8x2 is more in line with the minimalist design you started with, and every cent still count's, so I'll vote for the smaller option.

[lk]

Any of those two displays will work, do the job. And with the nokia one you will even be able to implement the decade display, so everyone wins

-lk

[rr100]

Snap poll please!

I vote for the small one as well, looks to be good enough and then yes, go small and go cheap. I can't imagine the size, I assume it is still readable at let's say 40cm on the bench (assuming reasonable eyesight...)?
How's the power consumption for the backlight (I assume it's LCD backlight...)?

[cyteen]

Standardizing on a more capable display has the advantage of buying in higher volume and being able to reuse excess stock on the next project and it saves on relearning/coding the interface as the same knowledge/libraries can be used. How much is convenience worth to you? At some point penny pinching on the input costs just devalues the final product.

Our russian friends at vrtp make use of the nokia screen for a variety of projects mostly using pic but atmel/arduino libraries are available.

[george graves]

Those cases look nice.  Are they custom or off the shelf?  You wouldn't happen to have a part number?

I've been looking for some cases with a "standard"screen cut out for a while.

[EEVblog]

I vote for the small one as well, looks to be good enough and then yes, go small and go cheap. I can't imagine the size, I assume it is still readable at let's say 40cm on the bench (assuming reasonable eyesight...)?
How's the power consumption for the backlight (I assume it's LCD backlight...)?

The 8x2 has a 4.75mm x 3.95mm font.
The Nokia screen of course can be anything you want. Not sure of it's exact display area.
A pure reflective 8x2 (i.e. no backlight) would almost certainly have better contrast than the nokia which is transflective with backlight.
The 8x2 can have a backlight and transflective too, and I think both take up to 20mA backlight current max.

Dave.

[MickM]

Hi Dave;
  why not put the pads in for both displays?
Maybe have a jumper to choose.

I would prefer the 16x2 HD44780 as I have some.

With your two choices though I pick the Nokia, it's more flexible.

Mick M.

[EEVblog]

Shame that neither of them are suitable for my new low profile Bench PSU case idea. Would have been nice to re-use.

Dave.

[caroper]

I vote 2x8 in the Quick Poll

[hlavac]

The 8x2 can have a backlight and transflective too, and I think both take up to 20mA backlight current max.

Okay, but with that 20mA you can drive the low current LED 7-segment displays with 2.5mA per segment, so whats the point?

[Aldobrandi]

I think it's coming down to either:
Nokia 5110 display 84x48

or a standard 8x2 text display

The 8x2 text display is about half the cost of the Nokia one.

Snap poll please!

Dave.

I also vote for the 8x2.

[hlavac]

That 8x2 will probably be better that the Nokia one

[amspire]

I would go with the Nokia display.

It would be better at showing both the set voltage/current and measured voltage/current at the same time, and also it means that the user guide can be built into the supply - particularly for things like software calibration. Supplies tend to last 20 or 30 years easily, and it is nice if you do not need to try and locate the PDF manual in 20 or 30 years when you need to recalibrate.

[EEVblog]

Okay, but with that 20mA you can drive the low current LED 7-segment displays with 2.5mA per segment, so whats the point?

a) You don't have to drive it at 20mA, it can be lower
b) You don't need to use the backlight at all

Dave.

[HackedFridgeMagnet]

Nokia

[Stephen Hill]

My vote would be for the Nokia.

[rolycat]

My vote is for the Nokia display.

More educational for the audience, and maybe more fun for the engineer.

[adam1213]

I vote for the 8x2 display. The nokia display would likely be overkill with limited benefits.

Independent of the choice of which of these displays I think the USB power supply will be useful.

[EEVblog]

I vote for the 8x2 display. The nokia display would likely be overkill with limited benefits.

I suspect the same. The Nokia would be fun, but essentially overkill.
The choice might eventually come down the physicality of it all though.

Dave.

[SeanB]

8x2 display, enough to use, but not too much, and no temptation to add frills that annoy after a while ( beep on keypress..............).

[G7PSK]

You can get cheaper Dave a 1mm thick by 2050 by 1250 mm can be had at £22.39 from these people I have never bought one offs normally get the pallet but that appears reasonable for small quantity.

[McMonster]

I'm sure the 8x2 display will be more than enough for this project. Does the job and still has some room for displaying some custom stuff if someone is bored enough to mess with a simple PSU firmware.