HP Forums

Full Version: [WP-34S] Cable and flashing options for Mac users
You're currently viewing a stripped down version of our content. View the full version with proper formatting.
Pages: 1 2 3 4 5 6
Unless someone has a better or more updated idea, I am planning to fabricate a cable starting with Katie Wasserman's detailed instructions documented here: Homemade ARM-based Calculator Programming Cable (thanks Katie!).

Next, I want to figure out a way to use a Mac to flash the WP-34S. What I do have is a serial port adapter and communication software that I routinely use to store backups of my HP-48GX, so there has to be a way to do it.

Does anyone have any updated information on such a project? I knew what I was getting into when I bought the WP-34S and never planned to flash it myself, but it's just too cool a device not to play with. Any advice or words of encouragement welcome.

Also, I presume HP's original serial programming cable has become so scarce it's not even worth looking for one, or am I wrong about that? I'm not sure what to look for or even what its correct name is. I know about Harald Pott's USB board, but I'm trying to keep things as simple as possible, without further modifications to the calculator's hardware.

Hi, John,
You may like to have a look to my project if you enjoy some diy.

Using a USB to RS232 TTL PL2303HX converter is the easier way to get a working flashing cable. It works virtually with any modern computer and OS (Linux, Mac, and all colors of Windows).

Ordering from China takes the time but the price is close to zero, and we can wait while preparing the remaining requisites. Even from eBay UK one can find samples for as low as 2 Pounds.

Please share your findings concerning the pogo connector if you decide to have a go on that.
Did you look at SourceForge? In the flashtools directory, you'll find a flash program for Mac.
It works sometimes but not always for reasons beyond my understanding (or my patience).
The other solution is to use a Windows virtual machine (VirtualBox, Parallels...) or Bootcamp and flash using the classic .exe tool.
Thank you for those links Jebem. So far I decided upon the USB cable you suggested, and the header socket strip Katie suggested. Given the unusual 2mm spacing there don't seem to be too many options regarding the latter.

The cable is so cheap I bought two of them.

(11-29-2014 07:13 AM)jebem Wrote: [ -> ]Please share your findings concerning the pogo connector if you decide to have a go on that.

I'm still evaluating which pins I will need since Katie's link is outdated. The dimension of the pin end that fits into the header socket is uncertain (edit: these look like they might work).
(11-29-2014 10:41 AM)pascal_meheut Wrote: [ -> ]Did you look at SourceForge? In the flashtools directory, you'll find a flash program for Mac.


Edited to add above link.

I hadn't bothered since I prematurely assumed there was none for the Mac. This is excellent information. Thanks!
(11-29-2014 05:50 PM)John Galt Wrote: [ -> ]I'm still evaluating which pins I will need since Katie's link is outdated. The dimension of the pin end that fits into the header socket is uncertain ...

After receiving the header sockets I think .68mm barrel diameter spring pins will work. The header socket pins are .5mm diameter and fit into their own sockets with a little wiggle room. If they don't work I'll have wasted about $3.50. In any event I can find no other spring loaded pins with any dimension closer to what appears to be required.

If anyone wants to search for them they are listed as "P50-B1 Dia 0.68mm Length 16mm 75g Spring Test Probe Pogo Pin". B1 apparently designates 30° sharp ends. The same pin with a hemispherical end will be listed as "P50-J1".
I wound up buying these parts:

• 2mm Pitch 2x3 Pin 6 Pin 6 Wire IDC flat Ribbon Cable with socket assembly
• P50-J1 Dia 0.68mm Length 16mm 75g Spring Test Probe Pogo Pin

The 0.68mm diameter pins are a very tight fit in the IDC socket, which I think are designed to accommodate about a 0.5 to 0.6mm diameter or square pin. I broke / crushed / lost a few of them in the process, but once inserted they won't come out easily.

Using pliers, grasp the pin at a right angle near its base leaving about 1mm of its base exposed. Insert that 1mm of the pin into the socket, then reposition the pliers so that it's grasping the pin lengthwise, and push all the way in. That method was least likely to bend / break / lose / crush the pins. I did not use the header socket strip Katie suggested, but if you elect to use that method instead the 0.68mm diameter pins fit that socket very nicely.

I still need to make a suitable mechanical connection since my initial efforts attempting to use strips of various metals failed - the aluminum and steel pieces I had were all too thin, so I need to find or buy some slightly thicker brass or copper. In the meantime I used this ugly but effective rubber band and popsicle stick arrangement:




BTW I realize it's overkill to fabricate this connector but I want a secure arrangement rather than holding a bunch of pieces together with three hands, and will probably build a simple circuit with pushbuttons and indicator LEDs when I get around to it.

I have all the other basic parts including the USB to RS232 TTL level cable recommended by Jebem (thanks Jebem!) but haven't tried flashing anything yet...
(12-31-2014 08:48 PM)John Galt Wrote: [ -> ][Image: attachment.php?aid=1381]

The problem with this design and my original connector is the pogo pins can get bent easily and lose their spring-action. Adding a second housing makes for a more robust connector. The housing may need to be trimmed to fit the opening in the 30b.

[Image: Conn%2BV2.JPG]

Thank you Dave. I've been struggling with a way to stabilize the pins so that won't happen, perhaps using something like "InstaMorph Moldable Plastic" but I have no idea if it can be worked accurately enough.

What are you using for the housing?

Are you using beryllium copper for the clip, or something else, and in what thickness?
Hi John,

For the additional housing I disassembled an IDC receptacle like the one used to make the plug. For the clip I initially used a cat food can, but then I picked up a brass strip at the local hobby shop that's 0.016" thick.

I looked into the beryllium copper sheet like Katie used, but it was something like $50 for a sheet. I have some strips of brass left over from when I was selling cable parts. If you're interested I can send you one.

Remember beryllium copper is hazardeous for your health (Be, not the Cu).

Thank you Dave, that's very gracious of you but I don't want you to go through the trouble.

I can obtain BeCu strip for a lot less than $50, my only question is the proper thickness. Is the thickness you used adequate, or would you have preferred thicker?

Rather than cannibalize one of the ribbon cable assemblies, I determined the machined pins in the header strips Katie used can be removed by pulling them out, leaving slightly oversized but properly spaced holes that can be filled in with epoxy or something similar. Epoxy would also secure the strips to each other, and to the existing socket. Two header strip thicknesses would adequately support the pins. Using a third might even fit the recess in the calculator, while leaving enough spring pin travel for reliable contact.

That, and the clip ought to closely resemble the connector you built.

Once again thanks, and happy new year!
The thickness of the brass strip was fine. It could even have been a little thinner. I would think that BeCu would be more flexible.
I found the aluminum flashing you can buy a a home hardware store worked well as the bracket. I was able to bend it without breaking it and it has held up to numerous useses.
The finished product.

I found some 0.020 stainless :-)

The reinforcement consists of three pieces of Katie's header socket, pins removed, cemented to one another with cyanoacrylate glue. The two pieces closest to the ribbon cable connector are 5 holes wide, and the one that fits into the calculator is 3 holes wide. I did not perceive a need to fill the space around the pins with epoxy; they appear to be secure enough.

The first photo shows how the sides were tapered by filing, in order to more easily fit the clip ends into the calculator.

I already fabricated a second, better looking (and better fitting) clip since the one in these photos was sized with some trial and error.

Thanks to Dave Frederickson for the ribbon cable connector idea.

Thanks, John. You're much too kind. Smile
Excellent work on the pogo connector. Thanks for sharing!
I read Mr. dewster's technique on http://www.thereminworld.com/Forums/T/29...b-to-wp34s.

Sounds easy and sensible enough, and the former HP-30b appeared to erase as expected (in that it now appears to be dead as a post with its batteries rapidly depleting) but I hit a snag with programming.

I am using the same cable he described, the imported one that costs < $2:


... with the latest driver from Prolific on a Mac found here:


(you have to log in - username / pw "guest" and "guest" respectively)

... and the wp35sflash program from the SourceForge archive here:


After connecting Rx and Tx to the proper pads through a 1K resistor and clicking the Flash button, the wp34sflash program replies either "No answer Cannot connect to WP34s". Repeated attempts return either that or "Invalid answer: 0x4e0x23 Cannot connect to WP34s". The hex code, when it appears, is usually the same. The battery voltage (running off a single battery) remains a steady 3.0V throughout.

TL;DR it just doesn't work :-(

What I have tried:

- Two USB PL2303HX cables. I did disassemble one to verify it is a real Prolific device.
- Yosemite and Snow Leopard
- Many resets

Any ideas?
(01-18-2015 08:30 PM)John Galt Wrote: [ -> ]Any ideas?

I've had the best results with chips/cables from FTDI and the Windows based MySamba software. The problem seems to be the synchronization phase. The boot loader in the Atmel chip cannot use the xtal oscillator even if it is equipped. It therefore sends some trigger bytes at what it assumes to be 115kbit/s. It then gets back an answer (or not) and retries with a slightly modified oscillator setting. Maybe the Prolific chips just discard the sync data if the baud rate is off too far. So the Atmel boot loader never knows how to adjust the frequency because it never sees any response from the PC or Mac.

Just guessing, I'm afraid.
(01-18-2015 09:56 PM)Marcus von Cube Wrote: [ -> ]
(01-18-2015 08:30 PM)John Galt Wrote: [ -> ]Any ideas?
I've had the best results with chips/cables from FTDI and the Windows based MySamba software.

Can you run a serial tty test program from your PC?
If yes, then you could test your PC to USB-serial-cable link, by connecting the TxD and RxD wires with one 1K resistor to from a loopback.
On your tty test program, you should receive every single character that you type on the keyboard.

I remember that on my initial tests (on Windows 7) I had a similar issue, and I found out that I was using the wrong serial COMx port number.
By doing the above test, I could find the problem and fix it.
Pages: 1 2 3 4 5 6
Reference URL's