HP-25C Eumulator

[brouhaha]

(12-29-2014 06:18 PM)Chris Chung Wrote:  P.S. for those who got the units, if the flux / rosin really bothers you, you can try and use alcohol / nail polish remover and a used toothbrush on them.

I'd highly recommend against acetone or nail polish remover (which used to be acetone, but now may contain who-knows-what). Acetone will damage many electronic components, including switches.

Isopropyl alcohol is highly recommended, though try not to get it into the switches.

In the US, avoid "rubbing alcohol" unless it is specifically "isopropyl rubbing alcohol". If it doesn't say isopropyl, by law it is ethyl alcohol with deliberately introduced contaminants including acetone.

[Chris Chung]

The 2nd batch PCB had arrived and I had test build one unit which went fine.

I will start building during the weekend and hopefully to ship them early / mid next week.

The cost again, is

US$27 for kits, US$36 for assembled units. Shipping is $3 for Canada, $5 for US and $8 for elsewhere.
I will PM / email individually and send payment instructions. Please reply confirming;

1. Number of kits / assembled units.
2. A mailing name + address formatted in multiple lines as you would write on an envelope.

2nd batch list
John, SlideRule, Brouhaha X2, PANAMATIK, Etienne, Lourens, viaPM1, viaPM2, BobVA, viaPM3 (11)

Thanks for your kind attention.

* This batch of PCB for some reason has "thicker" silkscreens which turn out quite nice.

For kit builders, please see the attached photo. This time I use a steel ruler to help align the tactile buttons and they turn out quite nice, also save me a ton of time. As mentioned before, the holes are a tad larger than it need to be so there used to be some alignment problems.

[Guenter Schink]

Hi Chris,

received my package today. It's really cool indeed. As I have one leather flip-open pouch from Michael Steinmann I figured its an almost perfect fit for the NP25. To stabilize the thing I folded an A4 sheet of paper to put under the lower half of the PCB. Seems to be hightech

I hope I've done the attachments right.

Günter

[BobVA]

I finally tacked together a little brass frame to let me install a display filter. I insulated the display connections with kapton tape to prevent any fireworks.
I'll probably paint the frame white if I decide to leave it on.

It's a lot more readable in bright light with the filter, but the bare display has more nerd panache.

[Chris Chung]

(01-03-2015 05:42 PM)Guenter Schink Wrote:  As I have one leather flip-open pouch from Michael Steinmann I figured its an almost perfect fit for the NP25. To stabilize the thing I folded an A4 sheet of paper to put under the lower half of the PCB. Seems to be hightech

Really nice on a leather case / folder. It appears the Swiss Micro is credit card sized. The NP-25 is a bit narrower and a bit taller. I would have made it credit card sized but as the width would exceed 50mm it cost more to fabricate the PCB.

(01-04-2015 07:56 PM)BobVA Wrote:  I finally tacked together a little brass frame to let me install a display filter. I insulated the display connections with kapton tape to prevent any fireworks.
I'll probably paint the frame white if I decide to leave it on.

It's a lot more readable in bright light with the filter, but the bare display has more nerd panache.

Now what you did make me look for brass coloured buttons to match the display housing. Would make the unit look really "steam-punk".

[Chris Chung]

Of the V3 1st batch, I received PM that one of the units have a digit gone blank. I believe it is a cold solder joint and if that is the case, it could be easily fixed w/ a soldering iron and some solder wires.

My 1st few builts had buttons stop working after a few weeks and I discovered that the soldering is weak. Afterwards the newer units I let my iron stay 1/2 second longer on each joint to make them more secure. Still it will happen and you can try and fix this.

If it is a lone tactile button, you could just re-heat the joint w/ a soldering iron, watch the solder melt and flow and sink / stick to the pad on PCB. You should "tin" your iron w/ a bit of fresh solder (new from your solder wire spool) before applying to the cold joint, otherwise it is difficult to melt the older solder on the joint. You can google "good / bad solder joints". This is a good visual..



Now if your failed tactile buttons are in a group of 3 or more, this means that the cold joint is on the IC side. And you need to follow the schematic / ic pinout (or ask me) to locate which IC pin corresponds to the failed buttons. And re-flow it to try and solve the problem.

The same applies to the LED display. If one digit / segment goes blank, and if at the same time you do not have button failures, it is likely that a joint on the LED modules went bad. And If it's digits not showing + some buttons fails, it is likely a joint on the MCU side, since a MCU I/O pin is shared.

The schematic w/ IC pinouts can be found in the source code (from my github repo). I am including the ascii schematic here; If one of the digits / segments failed, we can trace back which I/O port (digits are on MCU, segments are on 164 shift register) it is connected to, and find which pin is in question from the pinout diagrams.

It is easier for me as I would use a blank PCB and a DMM to trace the failed connections, and then re-flow the joints. In previous batches there are always a few cold solder joints and I need to re-flow after testing all the buttons and displays. For the latest batch, I had only 1 joint that I need to re-flow, so I guess I am getting better at them now.

Since the PCB design is components-on-both-sides, sometimes you cannot re-flow a join on the original size. In this case you should secure it on the other side (i.e. component side).

Code:


               MSP430G25x3
             -----------------
         /|\|                 |
          | |                 |
          --|RST  digit 0 P2.6|--\
            |     digit 1 P1.0|--\       digits bus (12)
            |     digit 2 P2.7|-----//--+---------+
            |     digit 3 P1.1|--/      |         ~  3 units of 4 digits bubble led
            |     digit 4 P1.2|--/      |         |
            |     digit 5 P1.3|--/      |    +---------+ +---------+ +---------+
            |     digit 6 P2.0|--/      |    | % % % % | | % % % % | | % % % % |----+
            |     digit 7 P1.4|--/      ~    +---------+ +---------+ +---------+    |
            |     digit 8 P1.5|--/      |                                           |
            |     digit 9 P2.1|--/      | digits bus x 3 scan lines                 |
            |     digit a P1.6|--/      +-----+-----+---/ ~~ /--+-----+-----+-----+ |
            |     digit b P1.7|--/  _=_ | _=_ | _=_ | _/ ~~ /=_ | _=_ | _=_ | _=_ | |
            |      scan X P2.5|-----o o-+-o o-+-o o-+-/ ~~ /o o-+-o o-+-o o-+-o o-+ |
            |      scan Y P2.4|-----o o-+-o o-+-o o-+/ ~~ /-o o-+-o o-+-o o-+-o o-+ |
            |      scan Z P2.3|-----o o-+-o o-+-o o-/ ~~ /+-o o-+-o o-+-o o-+-o o-+ |
            |                 |                                                     ~
            |                 |      (32 tactile button)                            |
            |                 |                                                     |
            |                 |        +--------+                                   |
            |             P2.2|--+---->|CLK ~CLR|---+---- Vcc                       |
            |                 |  |     |       B|---+                               |
            |                 |  |     |  0(d)QA|-\                                 |
            |                 |  |     |  1(f)QB|-\                segments bus (8) |
            |                 |  -     |  2(b)QC|--------------//-------------------+
            |                 | | |    |  3(a)QD|-/
            |                 | | |1k  |  4(g)QE|-/  74hc164 segment driver
            |                 |  -     |  5(e)QF|-/
            |                 |  |     |  6(c)QG|-/
            |                 |  +---->|A 7(h)QH|-/
            |                 |  |     +--------+
            |                 | === (102)    1 wire shift register via RC delay
            |                 | ===  1nF     to shift 1, Hi-Low-Hi
            +-----------------+  |           to shift 0, Hi-Looooooow-Hi (>20us Lo)
                                ___
                                ///

               74hc164
               o---------+
               |A     Vcc|
               |B      QH|
               |QA     QG|
               |QB     QF|
               |QC     QE|
               |QD   ~CLR|
               |Gnd   CLK|
               +---------+
    4 digit bubble led from sparkfun
    +--+--+--+--+--+
   |a  b  2  f  d  g|
   |1  e  c  3  h  4|
    +--+--+--+--+--+

    msp430g25x3 pinout (a=port1, b=port2)
    +--+--+--+--+--+--+--+--+--+
   |- b6 b7 CK IO a7 a6 b5 b4 b3|
   |                            |
   |+ a0 a1 a2 a3 a4 a5 b0 b1 b2|
    o--+--+--+--+--+--+--+--+--+

For this failed unit's missing digit, it is the 4th digit (i.e. 1st LED module). From the pin-out, this would be pin 6 (i.e. bottom row, 6th pin). The solder side has been hidden, so the proper fix would be to solder on the component side.

From the schematic, this digit (digit 3) is connected to I/O port P1.1(a1) of the MCU, refer to the pinout this would be pin 3. A reflow can refresh the connection. If it is this joint that failed, it would have affected also 3 buttons. So my guess is that the cold joint is on the LED module.

There is also a chance that the LED module failed. I do not think it is likely as I had gone thru 100+ LED modules and never experience one that fails.

I hope this is helpful when you encounter a cold joint in your unit.

[Chris Chung]

V3 2nd batch list
John, SlideRule, Brouhaha X2, PANAMATIK, Etienne, Lourens, viaPM1, viaPM2, BobVA, viaPM3 (11)


I had shipped 5 units + 3 kits this morning and have them crossed out from the list.
It usually takes a week to 10 days to reach destinations. Please prepare your CR2032 as it is not included.

[Marcus von Cube]

If you ever are about to build another batch I'm in for one. I guess I can handle the soldering.

[Chris Chung]

(01-05-2015 09:51 PM)Marcus von Cube Wrote:  If you ever are about to build another batch I'm in for one. I guess I can handle the soldering.

I will start a new list when there are 4 / 5 orders. There are already 3 via PM.
I am changing the tactile button hole size on the PCB for a better fit. Will order PCB in a few days time when done. It will usually take about 3/4 weeks for the boards to come in.

I am making a slight price change for new batches. Instead of CAN$, the price will be US$. I.e. US$30 / kit, US$40 / assembled unit. I just found out in this batch that Paypal charge me (not you) for the payment transfer and I want to have that covered. I am also paying US$ for procuring parts and the exchange rate is not in my favour. I hope you can understand that and find it reasonable.

[BobVA]

(01-05-2015 12:20 PM)Chris Chung Wrote:  Now what you did make me look for brass coloured buttons to match the display housing. Would make the unit look really "steam-punk".

I like it! A little brass tubing around the edges, maybe a tiny knife switch for power, change the font to something suitably Victorian. And of course re-name it to "Patented Perpetual Electro-Arithmometer, Model Twenty-Five."

Instead of a display filter, maybe optional brass & leather goggles with red lenses.

[Chris Chung]

(01-06-2015 02:09 AM)BobVA Wrote:  

(01-05-2015 12:20 PM)Chris Chung Wrote:  Now what you did make me look for brass coloured buttons to match the display housing. Would make the unit look really "steam-punk".

I like it! A little brass tubing around the edges, maybe a tiny knife switch for power, change the font to something suitably Victorian. And of course re-name it to "Patented Perpetual Electro-Arithmometer, Model Twenty-Five."

Instead of a display filter, maybe optional brass & leather goggles with red lenses.

Don't you think it's a bit extreme?

V3 batch 3 list
rposperi x 3, Marcus, Geoff (5)

[jebem]

(01-06-2015 12:57 PM)Chris Chung Wrote:  V3 batch 3 list
rposperi x 3, Marcus, Geoff (5)

Hi, Chris!

Could you please include me for ONE in KIT form?

Thanks!
Cheers,
Jose (Jebem)

[walter b]

(01-06-2015 12:57 PM)Chris Chung Wrote:  V3 batch 3 list
rposperi x 3, Marcus, Geoff (5)

Please count me in for one as well. I might use it in a nonfunctional Woodstock. Ooh, and my soldering skills leave plenty of space for improvement.

d:-)

[d b]

Chris; Please put me on the list to buy an assembled unit. Thanks - db

[Nigel (UK)]

I've just received the one I ordered before Christmas (it was delivered to the school I teach at and I have only just returned to work). It is a marvellous creation - well done! The display is plenty bright enough under electric light and the keys are positive and reliable. The personalised welcome message was a really nice touch.

Congratulations and thank you for producing something so entertaining!

By the way - are the flickering numbers on the display in slow mode identical to the flickering numbers on a real HP-25?

Nigel (UK)

[Chris Chung]

(01-07-2015 10:07 AM)Nigel (UK) Wrote:  By the way - are the flickering numbers on the display in slow mode identical to the flickering numbers on a real HP-25?

The flickering should resemble the real thing. Eric's code follows the ACT unit to every single flag in the registers which included the display on/off and segment controls. And my code follows his code very closely.

Not 100% sure, don't have a really calculator to compare w/. It appears so when I compare w/ a youtube video.

I especially like to see the flickering of the HP-33C test prog (9, sin, cos, tan,.... and reverse). It flickering way better than the HP-25C. Reminds me of Xmas lights.

I also put considerable thoughts in designing the key-scan, where Eric's code is truthful in that, when you press-n-hold the R/S button, it shows the current program step. I had to dedicate 3 I/O scan lines (from the MCU) in order to do that.

/EDIT The gentleman who has a failed digit (+ 3 buttons) just confirmed to me that it's a cold joint and have it resolved by re-flowing the joint w/ a soldering iron.

[Chris Chung]

Updating list. 2nd batch all allocated and shipped.

V3 2nd batch list
John, SlideRule, Brouhaha X2, PANAMATIK, Etienne, Lourens, viaPM1, viaPM2, BobVA, viaPM3 (11)

V3 3rd batch list
rposperi x3, Marcus (k), Geoff, jebem (k), walter (k?), Den (8 units)

Also please note that if you request via PM and wants to remain anonymous, please indicate so in your PM. Otherwise I would list w/ your forum name. It is easier for me to maintain the list and process w/ real names. It is also easier for all to check when / if I make mistakes.

[walter b]

(01-06-2015 03:59 PM)walter b Wrote:  

(01-06-2015 12:57 PM)Chris Chung Wrote:  V3 batch 3 list
rposperi x 3, Marcus, Geoff (5)

Please count me in for one as well. I might use it in a nonfunctional Woodstock. Ooh, and my soldering skills leave plenty of space for improvement

... thus I'll be grateful for an assembled unit.

d:-)

[brouhaha]

(01-07-2015 12:54 PM)Chris Chung Wrote:  

(01-07-2015 10:07 AM)Nigel (UK) Wrote:  By the way - are the flickering numbers on the display in slow mode identical to the flickering numbers on a real HP-25?

The flickering should resemble the real thing. Eric's code follows the ACT unit to every single flag in the registers which included the display on/off and segment controls. And my code follows his code very closely.

Not 100% sure, don't have a really calculator to compare w/. It appears so when I compare w/ a youtube video.

In Nonpareil ("Eric's code"), I made a serious effort to simulate the instruction-cycle behavior of the HP ACT, including how the display is refreshed one digit per instruction cycle. I did not specifically compare for exact matching of the display flickering, so there might be some differences, though in casual use it seems about the same.

As far as I've seen, Chris has done an excellent job of faithfully adapting the code to the microcontroller.

[jebem]

(01-07-2015 10:07 AM)Nigel (UK) Wrote:  By the way - are the flickering numbers on the display in slow mode identical to the flickering numbers on a real HP-25?
Nigel (UK)

Hi Nigel,

I have just uploaded one small video from my own HP-25, and it seems to be identical to the HP-25C and to this excellent NP-25 project.