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[Group Buy-19][O] TMS0803/5 Emulating Calculator With Bubble Display

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It is upto @@simpleavr now. If you decide to use amstam's leds, first batch PCBs and parts are on me.

 

I don't know about others. But I want to do both design and see how they come out.

 

The 8 digits one began as a compromise as I can't source 9 digit displays, but they turned out really nice looking, I will not abandon them.

 

I would stick to my plan but will also like to sample 3 digit ones from @@amstan (brightness, layout, size) to see how it looks, will work on another layout in a few days.

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A quick update.

 

The version 2 PCBs is not yet in my hands. They left HK last Friday (tracked via HKPost) and have not appear on CanadaPost's tracking system. So may be Custom officers are admiring them now.

 

I did a design w/ the "will have" 3 digit leds and it looked like this.

 

@@amstan @@bluehash

 

I am thinking of building may be 10 of these "limited edition" (depending on amstan's contribution, we need 3x per calculator) and let bluehash used them in future POTMs or incentives to member contributions. Afterall this is a donation from amstan.

 

I will test the led modules, work on a prototype, will take some time to realized this.

 

Here is the "limited edition" design.

 

post-23-0-84163000-1403704186_thumb.png

 

 

 

 

 

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Thanks to @@amstan

 

I got the bubble leds today. I did a quick comparison w/ the Sparkfun 4 digits ones. Looks like he's letting us to have the whole lot. Haven't count them yet.

I managed to blow one already (oops). 

 

These (amstan's) are substantially brighter, but when I have to drive 3 modules (3 digits x 3 instead of 4 digits x 2) instead of 2. So I expect a new design will be similar, may be just a little bit brighter.

 

They do have larger digits and a narrower viewing angle. And the bubble is more round / spherical which may magnify more.

 

 

p.s. amstan also includes other goodies for me. I haven't really go though all of them yet, quite a bit of SMT parts and PCB / kit? for his binary clock. Thanks again.

 

http://43oh.com/2013/12/geekify-your-desk-with-the-msp430-binary-clock/

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Haven't count them yet.

I managed to blow one already (oops). 

When I counted there were 81. I guess you have 80 now. heh.

 

I managed to blow one already (oops). 

These (amstan's) are substantially brighter, but when I have to drive 3 modules (3 digits x 3 instead of 4 digits x 2) instead of 2. So I expect a new design will be similar, may be just a little bit brighter.

How do you limit current on them? Aren't you worried that you get uneven brightness if you just use the pin current limit? At least the anodes should have a resistor for current limit(ideally a transistor as well, if you want higher currents).

 

Also.. a battery like the CR2032 can only give like 5mA, anything more and the voltage should drop.

If the voltage drops too low you might have glitches in the mcu and have problems with the program execution. You could solve that with a big cap.

 

p.s. amstan also includes other goodies for me. I haven't really go though all of them yet, quite a bit of SMT parts and PCB / kit? for his binary clock. Thanks again.

 

http://43oh.com/2013/12/geekify-your-desk-with-the-msp430-binary-clock/

I included the leftover parts for my binary clock. You might be missing a bunch of things(like the smpsu chip). But you should be able to get most of it operational with the bare minimum of parts.

 

You don't really need the smpsu if you don't run on battery and you already have 5V available. You can also bypass that mosfet on the 5V rail; it's completely useless, doesn't do what i wanted.

 

I haven't checked if i gave you a light sensor as well, for that you need a heat gun. Take note of the changes you need to make of the pcb, i had some pins swapped.

 

I also included 20 ws2812 leds for you to populate that board.

 

I also included a bunch of hitachi based lcd modules that I had laying around(i had a box with at least 50).

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When I counted there were 81. I guess you have 80 now. heh.

 

 

 
I guess the lone one is that 2 digit one. I tried it and it had different pinouts from the others.
I can't figure out how I blow the 1st one I tried. I is a bit weird as most times (if at all), I would blow "open" a segment or a digit so that it never lights up again. But for this one, I blown "close" the decimal point and now it's "attached" to segment c, d, e, f, g. Now the decimal shows up when one of those segments are "on".
 
How do you limit current on them? Aren't you worried that you get uneven brightness if you just use the pin current limit? At least the anodes should have a resistor for current limit(ideally a transistor as well, if you want higher current

 

 

I know it's not the proper way to do it. The original DataMatch 2500 has an sn75xxx led driver (which was extremely popular 30-40 years ago). When I multiplex I adjust the "on" cycles and "off" cycles on individual digits based on the number of segments each digits are showing to maintain even brightness.

 

Although rarely happens (to me), if you leave your IO pins direct driving your digit / segments w/o PWM or multiplexing over a few seconds, it can destroy your LEDs. It only happens to be when I am extremely not careful during debug. Also the older LEDs are more fragile.

 

Also.. a battery like the CR2032 can only give like 5mA, anything more and the voltage should drop.

If the voltage drops too low you might have glitches in the mcu and have problems with the program execution. You could solve that with a big cap.

 

 

The breadboard setup is even worse as it's 2xLR44 where I would imagine the pulse drain current be lesser. There is this excellent read from a TI white paper that explain how one could work out the "big cap" capacitance needed, really useful when you want to use CR2032s.

 

1 Introduction
 
When designing a small wireless sensor node to be powered by the popular CR2032 coin cell, some sources claim there is a 15mA

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You got to love CanadaPost. My PCBs are 20 minutes away from me yesterday and they managed to send it 400km away from me overnight.
 

Date Time Location Description Retail Location

Signatory Name

 

2014/06/27 06:50 WINDSOR Canada Post processing error; item re-routed. Possible delay  
 
2014/06/26 16:33 MISSISSAUGA Item processed  
 
2014/06/25 19:18 MISSISSAUGA Item has arrived in Canada and was sent for further processing.  
 

 

They did estimate I will receive them on Monday, just in time for a Canada Day build if they don't mess that up.

 

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New board came in today.

I assembled one to validate the electrical and everything is well.

I still need to fix some key mapping bugs but it will be s/w only.

Pardon the twisted buttons as I went out of these buttons and I have to resurrect them from the 1st fail built.

Don't know what happened to DX and my new batch buttons was shipped 4 weeks ago but nowhere to be seen.

 

@@bluehash I think it is safe for you to order parts to assemble your kits.

Attached are the PCB pictures, let me know if you want to change silkscreen lines. I can only do "text" w/ Fritzing. I will upload the PCB zip package on Wednesday if there are no changes. (the electrics are all ok).

 

You can also see at the last photo of hook-up for in-circuit programming. I don't have the old version builds for comparison no more as they had parted me one way or another. But this version works better when entering digits (w/ one hand) because of the improved key placement.

 

Also you need to decide which battery holder you want.

 

This one is easy to solder but thicker. I am using this one but it is harder to solder unless you use paste and heat it through, I am not using paste though, I just heat it through from the top of the copper tab in higher temperature. It's is very slim and looks nicer.

 

It may be worthwhile to search and order from ebay for same parts. My last two orders w/ DX really is not good. Really really slow. I actually order the tactile buttons from ebay 3 days ago as I don't know when I will be getting my DX orders.

 

I will update the source code once I fixed the minor key mapping issues.

 

post-23-0-04964100-1404170504_thumb.jpgpost-23-0-48546000-1404170515_thumb.jpgpost-23-0-84745700-1404170531_thumb.jpgpost-23-0-59314000-1404170543_thumb.jpg

 

/EDIT also for the device, it's sufficient to order G2402, G2412 as we don't need ADC etc.

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@@simpleavr This is awesome and thank you for the writeup. I forget, but is there a BOM list?

 

It would be the same as you put at the top of this thread,

 

except.

 

  • Instead of msp430g2452, we could use 2402, 2412, 2432 as we don't need no comparators nor adcs. Newark has the 2401, 2412 on sales.
  • Choice of a slimmer battery holder (smd) instead of the original thru-hole part.
  • One lone red 1.8mm led, I used this one, you can also use this new type.
  • One .1uF bypass cap for the new board design.

I am waiting for some buttons and another 5 set of bubble LEDs, has to build a few for friends.

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I would like to have ONE (1) complete kit... How can I have it?

I live in Italy, and I would like to know the complete price with S&H included!.

 

Please let me know, also if you have in mind to add a case for it!

It's a FANTASTIC design!

M

:-)

 

p.s. maybe a programmed chip, a bare pcb and 2 bubble displays, would be the same as having the complete  "kit"; the remaining items can ne found here easily!

Please let me know

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