My WP-34S : USB to Serial cable prototype

[jebem]

(06-24-2014 06:31 AM)anetzer Wrote:  

(06-23-2014 11:03 PM)jebem Wrote:  I have added a picture to the OP with a hand draft of a possible PCB layout.

The Part's Listing was added as well.

Thank you very much!

Andreas

You are welcome, Andreas :)
Thank you for your comments and remarks in this small project.
If you decide to have a go for the switch box, please share your results.

[jebem]

(04-11-2014 01:03 PM)jebem Wrote:  8.5) USB interface
- One USB-to-Serial TTL adapter based on PL2303HX;

John brought to my attention that not every single Prolific PL2303HX USB-to-Serail TTL adapters manufactured in China are following the same cabling wiring color schema.

Usually they take the Green for TXD, and White for RXD (on the Prolific PL2303HX side of course), but some other Chinese manufacturers don't follow it.

Thank you John!

So I have updated my diagram from the OP by removing the wires color references.

Please follow the diagram labeling instead (this has not changed from my original diagram):
- Prolific PL2303HX "TXD" goes to "RXD" in the calculator;
- Prolific PL2303HX "RXD" goes to "TXD" in the calculator;

If you have a copy of the old version of that diagram, please be aware of these Prolific PL2303HX adapter variants.
I have a bunch of these adapters, all acquired from China thru eBay from two different suppliers, and all use the initial color schema.
Live and learn.

[MarkHaysHarris777]

Jebem,
Thanks for sharing all this stuff. I'm getting ready to go on this; I wasn't going to build the box, but have decided to go for it just for fun (I'm opting for the pogo pins since I found some cheap on Sparkfun).

I am interested if you could describe any troubles or frustrations you may have had soldering headers directly to the main board--- thanks for the pics by the way.

I will post my pics as I progress too, should it help someone. I'm going with manhattan style bread-boarding and a slightly smaller box, but otherwise pretty much your design... thanks again.

Do you plan to flash with the batteries removed from the unit? I am concerned to supply a potential charging voltage to the cells--- don't want them to explode. I know they can't supply enough juice (especially if weak) so I get the reason for the voltage add in the box.

Have you actually flashed yet, or still just in testing phase?

Thanks in advance.

[jebem]

(01-23-2015 08:17 AM)MarkHaysHarris777 Wrote:  (1) I am interested if you could describe any troubles or frustrations you may have had soldering headers directly to the main board--- thanks for the pics by the way.

(2) Do you plan to flash with the batteries removed from the unit?

(3) Have you actually flashed yet, or still just in testing phase?

Hi Mark,

Welcome again to this nice MoHPC that I found just one year ago

You did mention Wang Computers. Did you work for WANG at some point?
I did, for about 20 years in Europe (Belgium and Portugal).
Wang PCS, Wang 2200 series, Wang OIS series, Wang VS series, you name it.

Looking back it is amazing how technology evolved this far and this fast!
It was only yesterday when a hard disk drive would store 10MByte (5MB internal and another 5MByte external mounting cartridges), where the disk heads flying over the pressurized disk surfaces did eventually "landed" over the disks, scratching them and destroying all the data!
I used to repair them, and at the end we had to do the alignment for compatibility reasons with other disk cartridges, using a alignment disk and a oscilloscope.


Concerning the WP-34S, I am a late adopter because I only discovered it after joining this forum.
So, others here are the real experts on the WP-34S, not me.

That said, electronics has been my second nature since tender age, despite it is more a hobby now, because I do not need these skills for my work.


To answer your questions:

1.
I never tried to solder pin headers to the PCB - I do not like to modify the original calculator structure. I'm a collector, you know...

And that is the reason why decided to build my own flash box.
I wanted a solution that allows me to flash any HP-20B or HP-30B as many times as I want. From scratch. And without any internal hardware changes.

However, I'm not that hand's skilled as many others here and elsewhere have reported repeatably:
"to flash the HP-30B, you just need an USB-to-Serial adapter. You do not need anything else..."

Well, I'm not able to flash the HP-30B by just using 3 bare wires from the USB-Serial adapter, touching the HP-30B's POGO back connector, while at the same time being able to use a clip to Reset the HP-30B, while pressing a key on the HP-30B, and then be able to press the Send on the PC program to upload the firmware...
This procedure would require me to have at least 3 hands
No offense to the other more skilled people here and elsewhere - I'm just having some fun here - no intention to start flame war at all. Apologies to anyone taking this statement as an offense


2.
I never use batteries inside my calculator when flashing.
That is why I have a dedicated 3.3V supply in my flash box cable.


3.
Yes, I use my flash cable as many times I need to.
Again, this method was shared to me/us by other more skilled people here in the MoHPC.
In fact, to flash a HP-20B or 30B, one just need a PC, a USB-to-TTL-Serial adapter and those 3 hands to handle the flash procedure

I have just built this flash cable to be able to use dedicated press buttons, like in the original HP flash cable. However, while the original HP flash cable was using PC serial interface, I'm using a PC USB interface as shared by other people here before me.

One final note, if I may:
The POGO connector is really tricky to build, and as i see it, it is the real challenge here.
One's need skilled hands and workmanship to succeed in building a functional POGO connector.
Obviously it is not my case, but I managed to build a working POGO connector afetr a few iterations and using different techniques.
Perfectible, yes, but I'm not looking for perfection. I'm happy with it as long as it fulfill my needs

If you decide to have a go and build your own flash box cable, please share it in this excellent MoHPC forum!

Cheers!
Jose

[Dave Frederickson]

(01-23-2015 02:21 PM)jebem Wrote:  Concerning the WP-34S, I am a late adopter because I only discovered it after joining this forum.
So, others here are the real experts on the WP-34S, not me.

While I'm very impressed by enthusiasm people have gone to in making what is simply a programming adapter, I'm rather disappointed in the completeness of the documentation. Recall that we've been re-purposing 20b and 30b calculators for almost seven years, yet most people look no further than this forum in doing their research and completely overlook the Old Forum and the six years worth of experience re-purposing calculators that can be found there.

Lets not forget:

• Richard Nelson's Interfacing to the HP20b V3
• The HP20b Development Kit, released by Cyrille, which includes schematics of the calc
• Harald Pott's USB adapters
  

While sometimes the journey is half the fun, building a programming adapter is simply a means to an end. If you're only interested it turning a 30b into a WP 34S or WP 31S then save yourself a lot of frustration and time, get a ready-made adapter and show some support for those who followed this path before you.

Dave

[jebem]

(01-23-2015 04:46 PM)Dave Frederickson Wrote:  While sometimes the journey is half the fun, building a programming adapter is simply a means to an end. If you're only interested it turning a 30b into a WP 34S or WP 31S then save yourself a lot of frustration and time, get a ready-made adapter and show some support for those who followed this path before you.

I couldn't agree more.
Even more, if your goal is to just have a WP-34S to play with, why not support Eric and get one ready made for you?

[Dave Frederickson]

(01-23-2015 04:59 PM)jebem Wrote:  

(01-23-2015 04:46 PM)Dave Frederickson Wrote:  While sometimes the journey is half the fun, building a programming adapter is simply a means to an end. If you're only interested it turning a 30b into a WP 34S or WP 31S then save yourself a lot of frustration and time, get a ready-made adapter and show some support for those who followed this path before you.

I couldn't agree more.
Even more, if your goal is to just have a WP-34S to play with, why not support Eric and get one ready made for you?

Because some people like to have a little fun. One still needs to obtain overlays, so I'm still supporting Eric, just in a smaller way. Also, one needs a way to install updates.

[jebem]

(01-23-2015 05:03 PM)Dave Frederickson Wrote:  

(01-23-2015 04:59 PM)jebem Wrote:  I couldn't agree more.
Even more, if your goal is to just have a WP-34S to play with, why not support Eric and get one ready made for you?

Because some people like to have a little fun. One still needs to obtain overlays, so I'm still supporting Eric, just in a smaller way. Also, one needs a way to install updates.

I believe there was a missed business opportunity here:
Selling ready made WP-34S units modified with Harald's USB integrated interface.
That would probably have brought a few more adepts for the cause.

[Dave Frederickson]

(01-23-2015 07:14 PM)jebem Wrote:  I believe there was a missed business opportunity here:
Selling ready made WP-34S units modified with Harald's USB integrated interface.

Probably not, but that's not the board from Harald to which I was referring. You may have noticed that Harald offers several versions of USB-Serial adapters. The one to which I refer is the one with the two buttons, similar to the original RS-232 cable from HP. This is the board Katie used in her project.

However you choose to connect the adapter to the 30b, this is the easiest way to get a programming adapter (solder six wires and you're done). Harald also sells crystals and caps, so one-stop shopping! I chose to buy an adapter from a forum member, but if you want to build your own that's fine.

Dave

[MarkHaysHarris777]

(01-23-2015 02:21 PM)jebem Wrote:  Welcome again to this nice MoHPC that I found just one year ago

You did mention Wang Computers. Did you work for WANG at some point?
I did, for about 20 years in Europe (Belgium and Portugal).
Wang PCS, Wang 2200 series, Wang OIS series, Wang VS series, you name it.

Thank you, and thanks for the specific responses to my questions. Some of this will be off-topic, but bare with me, I'll try to keep it short.

I did not work for Wang. I did eventually complete a 25 year career with IBM as a Staff Software Engineer. I did spend many pleasant hours programming the Wang 700C series scientific programable calculator. You programmed that model the same way you program the WP34s. But, the Wang could also be programmed with OP codes by toggling them into memory one by one (as on the 8080 MITS Altair 8800) with toggle switches (on the high order) and push buttons (metal dome switches like HP keys) on the low order. I really think some of the pleasure I get from programming the HP35s goes directly back to my early programming experiences on the Wang 700C.

I am going to try to make a pogo plug (clips and all). In the mean time, I have absolutely no problem tinning the pogo pads and tack welding the six wires temporarily directly to the pcb on my experimental unit. In the long haul I think the pogo clip plug is the best overall solution and I'm looking forward to giving it a try.

Thanks again for your help. I'll post my own results too.

Good to chat with you.
Cheers,

[jebem]

(01-23-2015 08:15 PM)Dave Frederickson Wrote:  You may have noticed that Harald offers several versions of USB-Serial adapters. The one to which I refer is the one with the two buttons, similar to the original RS-232 cable from HP.

However you choose to connect the adapter to the 30b, this is the easiest way to get a programming adapter (solder six wires and you're done). Harald also sells crystals and caps, so one-stop shopping! I chose to buy an adapter from a forum member, but if you want to build your own that's fine.

Dave

Thanks, Dave, for your advertizing here on Harald's solutions.
As you say, not everyone has the skills or the time to do it yourself and build from scratch, reinventing the wheel.

Concerning the WP-34S support, I have contributed with money not only on the Eric's keyboard overlays, but also for the WP-34S open source project.

That said, and to clarify my point once for all:
Harald's offerings do not fit my needs.

As stated in my initial post, I needed a flash box integrating:
- Independent power supply;
- Visual monitoring on all operations;
- Press buttons for the flash procedures;
- Maintain the calculator integrity by using a home made POGO connector;
- Low cost solution.

Like many others in this forum, I enjoy DIY and have the required skills, so I decided to create my own design to fulfill my requirements.
Because I like to share knowledge with others, I have shared the results here.
That's all.

[jebem]

(01-24-2015 08:42 AM)MarkHaysHarris777 Wrote:  I am going to try to make a pogo plug (clips and all). In the mean time, I have absolutely no problem tinning the pogo pads and tack welding the six wires temporarily directly to the pcb on my experimental unit. In the long haul I think the pogo clip plug is the best overall solution and I'm looking forward to giving it a try.

Hi Mark, thanks for sharing your experience here.

Concerning the serial cable, if you are into DIY and the current market offerings do not cover your requirements, my simple design can help (yes, it is really simple when ones has the minimum electronics background to cope with it).

Please do not overlook the existing market offers, as Dave has remarked here and elsewhere:
There are solutions from Harald that may fit your needs.

One final word on tinkering inside the calculator: I'm not that fan of soldering wires directly into the HP-20B/30B.
Let me state the obvious here, if you do, you will not want to solder directly on the 6 pads, because after that it will be impossible to use them with the POGO connector.

Once again, the POGO connector is the way to go, but I find it tricky to build. Mine required half dozen iterations and different designs before settling with Dave's design.

[Dave Frederickson]

(01-24-2015 09:12 AM)jebem Wrote:  Thanks, Dave, for your advertizing here on Harald's solutions.
As you say, not everyone has the skills or the time to do it yourself and build from scratch, reinventing the wheel.

I didn't say that and I would appreciate it if you would not misquote me in your posts.

What I meant is that working solutions exist for flashing a 30b and if flashing a 30b is the goal then there's no point in redesigning something that already exists. Now if you improved on Harald's design my making it simpler or cheaper, then those would be acceptable reasons for "reinventing the wheel".

The triangular wheel is not an improvement on the square wheel because it eliminates one bump.

May I ask, in undertaking this project, other than adding LED's, what were your design goals?

[jebem]

(01-24-2015 06:00 PM)Dave Frederickson Wrote:  

(01-24-2015 09:12 AM)jebem Wrote:  Thanks, Dave, for your advertizing here on Harald's solutions.
As you say, not everyone has the skills or the time to do it yourself and build from scratch, reinventing the wheel.

I didn't say that and I would appreciate it if you would not misquote me in your posts.

What I meant is that working solutions exist for flashing a 30b and if flashing a 30b is the goal then there's no point in redesigning something that already exists. Now if you improved on Harald's design my making it simpler or cheaper, then those would be acceptable reasons for "reinventing the wheel".

The triangular wheel is not an improvement on the square wheel because it eliminates one bump.

May I ask, in undertaking this project, other than adding LED's, what were your design goals?

Hi, Dave,

I don't know if I did improve it or not, because I do not have or use Harald's solutions.
But I never claimed to improve on anything...

What I needed is what I got with my project. I'm happy with it.
I have all the monitoring information I need and on top of that, I have a top class 3.3VDC power supply to assist during the flashing procedures.

I'm not concerned about the cost either.
This was one of my hobby projects and I'm very proud of it.

[ijabbott]

I tried Micheal Kathke's SIL socket technique, but ended up ripping off one of the pads on the PCB when I put the case back on. I obviously didn't make the whole big enough. I made the hole big enough and tried it on a second HP 30b. This time the hole was big enough, but as the sockets poked out slightly above the hole in the case, I ended up ripping four pads off the PCB when I slid the battery cover back on.

On my third HP 30b (when it arrives), I don't think I'll bother trying to fit SIL sockets!