HP Forums

Hi all,
. I recently acquired a 20b to re-purpose into a 34s and was wondering if anyone could confirm whether a cable such as THIS ONE would be adequate for flashing it? Obviously I'd need to make the end connect up properly with 20b, but just wondering if the cable itself will do the trick, or, if something else is necessary?

If I've been reading posts and articles correctly, this ought to work, but thought I'd confirm with the many fine folks here who know for certain.

Thanks all.

The above link leads to a "Page not found" error for me, so I can't comment on the particular cable. Any USB to TTL with 3.3V logic (not 5V!) and that preferably brings out the 3.3V supply will work. I'm partial to those that use the FTDI chip myself. You should find pointers to instructions for building the programming cable here on this site.

~Mark

Thanks for the reply

That's weird... the page truncates the full URL. I edited the original post and added an embedded THIS ONE link. That appears to work.

I did buy one of those but couldn't get it to work correctly with my desktop system running Windows 10 Professional. When I bought a different adapter from Eric Rechlin's site, it proved worth the money.

Alan

Compatibility problems is one of the reasons I avoid the clone or knockoff cables. Sometimes you get exactly what you pay for One of my go-to sites for these things is Sparkfun ( http://sparkfun.com/ ) which has the USB to Serial cables and breakout boards. I used a breakout board to build a programming cable.

(09-29-2017 12:08 PM)striegel Wrote: [ -> ]I did buy one of those but couldn't get it to work correctly with my desktop system running Windows 10 Professional. When I bought a different adapter from Eric Rechlin's site, it proved worth the money.

Alan

The cable on Eric's site is USB to RS-232. This is definitely NOT the cable to use unless you have one of the HP RS-232 programming adapter cables.

As Mark pointed out, a cable that brings out 3.3V power is desirable if you want to incorporate the RESET and PROGRAM switches like on Harald's board in Katie's article.

http://www.hpmuseum.org/cgi-sys/cgiwrap/...ead=229916

Once you have the cable electronics figured out you can fashion a plug.

http://www.hpmuseum.org/forum/thread-609.html

I added a second connector housing to help prevent the pogo pins from getting bent.



Good luck!

Something like this ?

(09-29-2017 06:44 PM)jch Wrote: [ -> ]Something like this ?

No, that's Harald's internal board. That requires modification of a 20b/30b and is good for one calculator. Plus, there are no more of those.

The topic of this thread is how to make a USB version of the HP programming cable adapter using a USB-LVTTL adapter cable. Good for many calculators and no calculator modifications required.

Dave

Thanks for all the great info everyone!

I just use an FTDI TTL 3.3V cable, a couple of 1K resistors for the RX and TX lines, and a steady hand!