NP-41 Emulator (may be)

[smp]

I *really* want to get one of these, with the case and keyboard.

Any idea when you might be taking orders?

Thanks,
smp

[Chris Chung]

(03-01-2016 02:26 PM)rprosperi Wrote:  Can you guess about when these will be available, and also will it be possible/straightforward to update the firmware, e.g. via USB?

(03-01-2016 04:23 PM)Massimo Gnerucci Wrote:  Gimme, gimme, gimme one (at least!)...

(03-03-2016 01:28 PM)smp Wrote:  Any idea when you might be taking orders?

I didn't plan to sell the 14-segment version. The build is difficult and time consuming. The fact that I need to direct drive segment-by-segment the LCD glass make the hand soldering quite challenging. Many times I have to re-work / re-flow to get things right. Let alone the fact that I had messed up two builts.

I had a few (< 10) custom LCDs left, likewise I had may be 6 or 7 PCBs (both head and keyboard unit). If you think you had good skills and really like one of these, I can assemble a few kits (i.e. all the parts needed). You will, however purchase an appropriate TI launchpad and use it as a programmer. This will allow you to load the firmware and update / change it in the future.

Also the PCBs had bugs (you can see them on the photo I uploaded) and require 2 jumps.

My focus remains on the smaller NP-41S, where I am focusing to turn it into a kit / assembled kit. The built is a lot easier (and way quicker) and it should be more reliable. Please wait for the next version which hopefully will be the kit version. I think if everything goes well, I will received my boards in 2 weeks time, and another week to built it. So after a month I may be able to offer up to 4 kits / builts for early adopters. I had only ordered 4 LCD modules this time. I also recommend to get this launchpad as programmer, the firmware is still work-on-progress, but already fun to play w/.

Currently, the way I load ROM modules is to compile them into the firmware. I am working on a UART loading mechanism. It will most likely require a terminal program like putty, realterm or something similar. This will also be a WIP for the NP-41S, as I will also be experimenting serial ROM to expand it's capability.

Once a NP-41S becomes stable, we may want to evaluate again the feasibility of the 14-segment version. It will only be feasible if there are enough interest to trigger a LCD production batch (300 units min.) and me investing into better SMD equipments.

[Massimo Gnerucci]

Thank you Chris, I like your works very much but I can wait for a stable version. Furthermore I think it's better to follow your recommendations.
I love the 14 segments display but if it will prove to be too much difficult to assemble I'll gladly get a 41S instead.

Probably I will buy more than one but, alas, cannot vouch for 300! :)

[rprosperi]

(03-03-2016 05:27 PM)Chris Chung Wrote:  You will, however purchase an appropriate TI launchpad and use it as a programmer. This will allow you to load the firmware and update / change it in the future.

For those of us that are not h/w developers, what set of skills would be required to update the f/w, or even to add a ROM image, etc. using this Launchpad? At $10, there's no decision to be made, and I can do things like burn EPROMS, download files, etc. but no idea if one needs soldering skills, etc.

(03-03-2016 05:40 PM)Massimo Gnerucci Wrote:  Probably I will buy more than one but, alas, cannot vouch for 300!

1 + ( or maybe it should be 2 +, but certainly 300 NOT)

Thanks for sharing the plans and timing Chris, keep up the great work!

[PANAMATIK]

(03-03-2016 05:27 PM)Chris Chung Wrote:  Once a NP-41S becomes stable, we may want to evaluate again the feasibility of the 14-segment version. It will only be feasible if there are enough interest to trigger a LCD production batch (300 units min.) and me investing into better SMD equipments.

Great work! I want to have +1 too, so only 297 to go.

Bernhard

[Thomas_Sch]

(03-06-2016 11:52 AM)PANAMATIK Wrote:  

(03-03-2016 05:27 PM)Chris Chung Wrote:  Once a NP-41S becomes stable, we may want to evaluate again the feasibility of the 14-segment version. It will only be feasible if there are enough interest to trigger a LCD production batch (300 units min.) and me investing into better SMD equipments.

Great work! I want to have +1 too, so only 297 to go.
Bernhard

+1 for me,
296 missing.
Thomas

[Jlouis]

1+

Only 295

[Sylvain Cote]

+1 (294 left)

Sylvain

[Guenter Schink]

+1 (292 left)

[Chris Chung]

(03-06-2016 11:52 AM)PANAMATIK Wrote:  

(03-03-2016 05:27 PM)Chris Chung Wrote:  Once a NP-41S becomes stable, we may want to evaluate again the feasibility of the 14-segment version. It will only be feasible if there are enough interest to trigger a LCD production batch (300 units min.) and me investing into better SMD equipments.

Great work! I want to have +1 too, so only 297 to go.

Bernhard

Thank you all for interested in and supporting this project. We do not need 300 NP41 units to make this feasible. 50 committed buyers would be enough. A batch of 300 LCDs will cost around US$500 (I hope my estimate is close, there are quite a bit of logistic cost here). With 50 kits, I can assume a $10 LCD unit cost.

My feeling is that I would probably get 50 committed takers but we all cannot make commitments when there is not even a price. I do not have a price yet as there are still some variables. Except that it will be reasonable (compare this w/ NP25), I would say it will be between US$50 and US$80. There will be a simple 3D printed back case only. I found out the keytops is not giving any functional and visual advantages except that it took me 3 hours to print one.

This is the revised case which is thinner than the last one as I am not attaching a keypad.

   

It is comfortable to hold and the PCB has all the key legends and I found it works and looks better than w/o the keypad.

   

Unfortunately because of the length, I still have not yet perfected the print and there is still wrapping on the far corner. I need to adjust my 3D printer and / or print parameters to improve this.

   

/EDIT, I know the K, L, M and O, P letter legends on the PCB are off. Have to fix them on next PCB batch.

[smp]

(03-07-2016 08:21 PM)Chris Chung Wrote:  My feeling is that I would probably get 50 committed takers but we all cannot make commitments when there is not even a price. I do not have a price yet as there are still some variables. Except that it will be reasonable (compare this w/ NP25), I would say it will be between US$50 and US$80. There will be a simple 3D printed back case only.

For that price, I am definitely in for one of these! (291 left) *or* (41 left)

smp

[Massimo Gnerucci]

(03-07-2016 10:20 PM)smp Wrote:  

(03-07-2016 08:21 PM)Chris Chung Wrote:  My feeling is that I would probably get 50 committed takers but we all cannot make commitments when there is not even a price. I do not have a price yet as there are still some variables. Except that it will be reasonable (compare this w/ NP25), I would say it will be between US$50 and US$80. There will be a simple 3D printed back case only.

For that price, I am definitely in for one of these! (291 left) *or* (41 left)

smp

Ditto! One for sure, and probably two, depending on final features. So, maybe, we're already at 40 left.

[sa-penguin]

That keypad looks wonderful...
At the risk of derailing your work in progress, would you consider selling just the keypad?

If made as a USB style keyboard, I could probably plug it into my Nexus 7 Android, and use / make my own calculator app.
I could even arrange screen & pad independently, in portrait / landscape mode, as I see fit.

[Chris Chung]

(03-09-2016 02:56 AM)sa-penguin Wrote:  That keypad looks wonderful...
At the risk of derailing your work in progress, would you consider selling just the keypad?

If made as a USB style keyboard, I could probably plug it into my Nexus 7 Android, and use / make my own calculator app.
I could even arrange screen & pad independently, in portrait / landscape mode, as I see fit.

I assume you mean the keys PCB. It is not intelligent, more of just a physical matrix of keys and battery holder. There will be a lot of work to implement your idea.

An easy way is to pair w/ some known solutions that employs an MCU that has USB capabilities.

My keypad design, however, is not the common rows x columns layout. To save GPIO pins, they have additional multiplexing.

I am using 10 pins for the keys, w/ R x C layout, the most I can do is 5 x 5 or 25 keys.
Instead, I scan my 10 pins like so.

pin 0 scans w/ 1 2 3 4 5 6 7 8 9
pin 1 scans w/ 2 3 4 5 6 7 8 9
pin 2 scans w/ 3 4 5 6 7 8 9
pin 3 scans w/ 4 5 6 7 8 9
.... etc, this setup allows me to scan 45 keys.

If you like to try use this PCB, I can send one to you on shipping cost. Another idea is to install Fritzing and with my design file, you can add a ProMicro, or similar device (< $4) for a more complete solution.

[Chris Chung]

A member is getting the parts to do a build (14 segment version). As it is still prototyping quality, there are a few tips / instructions needed. I am putting them here in a reply so that it could be useful in the future to others who want to duplicate this.

I am not releasing the source / PCB design at this moment. They are not good to look at (messy as usual). And whoever is interested in them can PM me.

The keypad PCB is rather straight-forward. Same technique as in NP25 where you have to bent the SMD tactile buttons w/ a pair of long nose pliers and use them to fit the thru-holes. A CR2032 battery holder also on the underside.

The current PCB has 2 missing traces (design fault, I missed them) and they need to be added back. I just use resistor legs, but any wire would also do. See below.

   

For the "Head" unit, the design is also minimal. Apart from the MCU, there are 3 x 0.1uF bypass caps, a 10uF for power and a 4.7uF for the LCD charge pump.

The MCU should be soldered 1st and be examined properly w/ a magnifying glass. I had upgraded to use solder syringes and hot air gun, and still my most recent build requires a few re-flowing, caused by uneven solder paste application.

The LCD glass, do require some attention, to fit the layout, some 5 pins in the middle need to be bent (see various previous photos) and solder as surface mount.

   

To connect the 2 PCBs together, I am using common 0.1" header pins. My original idea is to allow tryouts of having the head unit tilt up better viewing angle.

I did not plan ahead when I solder the head unit (the keys PCB was not done when I do this), I had solder the female header too far from the PCB edge, I am using a thru-pin female header as SMD (for cost and availability reasons) and I should have position it close to the edge.

The result is that the male pins from the keys PCB could not fit reliably w/ the female side. Eventually I had to reshape the male pins (they are right angle pins) to extend and lower them for head unit fitting.

   

So to sum it up, my advice would be

• Solder MCU 1st, check the work and see if reflow is needed.
• Solder other parts EXCEPT all header pins and LCD.
• Play w/ the LCD and decide if and how much elevation is needed. This is similar to NP25 as parts on both sides interfere w/ each other. My build had the LCD elevated 1.5mm. Insert LCD, insert the 4 pin header for programming, the female headers (if part of these pins goes thru the PCB). decide the best fit before soldering.
• Solder the LCD, I would just solder 2 or 3 corner pin only at this stage.
• Layout both PCBs and trial fit the 2x 8 pin header connections. Decide and fix the female headers.
• Solder header pins.
• Solder reset of LCD pins.
  

[Harald]

Hi Chris,

thanks for the info!
I think the build will be easy with those instructions.
However, I didn't quite understand how your key scanning works

(03-09-2016 01:49 PM)Chris Chung Wrote:  ...
Instead, I scan my 10 pins like so.

pin 0 scans w/ 1 2 3 4 5 6 7 8 9
pin 1 scans w/ 2 3 4 5 6 7 8 9
pin 2 scans w/ 3 4 5 6 7 8 9
pin 3 scans w/ 4 5 6 7 8 9
....

Do you have a schematic for the keyboard? That might help me understand what you are doing.

Cheers,
Harald

[Chris Chung]

(03-09-2016 03:35 PM)Harald Wrote:  Hi Chris,

thanks for the info!
I think the build will be easy with those instructions.
However, I didn't quite understand how your key scanning works

(03-09-2016 01:49 PM)Chris Chung Wrote:  ...
Instead, I scan my 10 pins like so.

pin 0 scans w/ 1 2 3 4 5 6 7 8 9
pin 1 scans w/ 2 3 4 5 6 7 8 9
pin 2 scans w/ 3 4 5 6 7 8 9
pin 3 scans w/ 4 5 6 7 8 9
....

Do you have a schematic for the keyboard? That might help me understand what you are doing.

Cheers,
Harald

I did not properly draw a schematic, I just used Fritzing to "draw" the PCB using it's manual trace routing.

Here is a simplified schematic for a 5 pin key multiplexer to illustrate the connection and scanning, it yields 4 + 3 + 2 + 1 keys.

   

In the firmware I start by placing pin 0 (say from top) as output set to high, pin 1, 2, 3, 4 as input w/ pull-down to low. And I would scan for the 4 input pins to see any of the 1st row keys has been hit.

On the next scan cycle I would place pin 1 as output to high, and scan for pin 2, 3, and 4. I won't scan pin 0 here as it was done in the last scan cycle.

Likewise on the next can cycle we can the next row w/ one fewer inputs / buttons.

[PANAMATIK]

(03-09-2016 02:56 AM)sa-penguin Wrote:  That keypad looks wonderful...

I agree! And it shows the same style as the NP-25. Both together could be nice twins lying on a desk or placed in a showcase.

The keyboard matrix with changing input/output pins is also a slick idea. It scans n*(n-1)/2 keys with n lines compared to (n/2)^2 with a conventional matrix.


Bernhard

[Harald]

(03-09-2016 06:21 PM)Chris Chung Wrote:  

(03-09-2016 03:35 PM)Harald Wrote:  Hi Chris,

thanks for the info!
I think the build will be easy with those instructions.
However, I didn't quite understand how your key scanning works


Do you have a schematic for the keyboard? That might help me understand what you are doing.

Cheers,
Harald

I did not properly draw a schematic, I just used Fritzing to "draw" the PCB using it's manual trace routing.

Here is a simplified schematic for a 5 pin key multiplexer to illustrate the connection and scanning, it yields 4 + 3 + 2 + 1 keys.



In the firmware I start by placing pin 0 (say from top) as output set to high, pin 1, 2, 3, 4 as input w/ pull-down to low. And I would scan for the 4 input pins to see any of the 1st row keys has been hit.

On the next scan cycle I would place pin 1 as output to high, and scan for pin 2, 3, and 4. I won't scan pin 0 here as it was done in the last scan cycle.

Likewise on the next can cycle we can the next row w/ one fewer inputs / buttons.

Ahh, now I get it! Thanks for the explaination, that is a very clever Idea.
That way with n lines you can scan n*(n-1)/2 keys.
The conventional way it would be (n/2)^2.

[PANAMATIK]

(03-09-2016 07:03 PM)Harald Wrote:  Ahh, now I get it! Thanks for the explaination, that is a very clever Idea.
That way with n lines you can scan n*(n-1)/2 keys.
The conventional way it would be (n/2)^2.

Seems we got the same results Approved!

Bernhard