HP-15C CE woes: 1 bug, 2 limitations, 3 questions

[Steve Simpkin]

(10-14-2023 12:20 PM)Divasson Wrote:  Is not the same cable - it needs to be modified (the 15c CE uses USB protocol and the pin connections are different from the original. There was a description of the two different pin arrangements in a past thread - possibly when discussing HP12c versions). The mod is "destructive": you will not be able to use the cable with the 15c LE anymore.

I think post #24 in the following thread is what you are referring to. It describes the pinout of the 2x3 connector used in the 2015 and newer HP-12C compared to the older serial pinout used on earlier models. I suspect this is still relevant for the HP-15 CE.
https://www.hpmuseum.org/forum/thread-51...l#pid46057



Further along in post #35 of the same thread, Tim Wessman describes an unfortunate "oversight" in the hardware design of the 2015 and newer HP-12C that would permit a standard surface mount Micro USB connector to be used on the HP-12C. I hope it is still relevant to the HP-15 CE.
https://www.hpmuseum.org/forum/thread-51...l#pid46108

"However, due to a serious oversight in our electrical design, someone accidentally left a surface mount on an extreme edge of the boards that happens to perfectly fit a surface mount micro USB. These pads were also accidentally connected to the internal USB circuitry of the chip. Should you accidentally cut a small hole in the plastic case on the edge that accidentally lines up with the accidental surface mount, you might be able to accidentally use USB to do reprogramming. Happy accidents! (obviously voids your warranty)"

In post #41, Katie Wasserman has some photos showing the above details.
https://www.hpmuseum.org/forum/thread-51...l#pid46221

https://wass.net/images/IMG_1057.JPG