use cases for USB OTG port on calculator?


If you had a USB OTG port on a calculator (with capabilities otherwise similar to a 41CX, 42S, or WP-34s), so that it could be connected not just to USB hosts such as a PC, but also to USB devices, what kind of devices would you want to use it with, and why?

(This question should not be interpreted as a commitment to provide a product with a USB OTG port.)


My number one choice would be for storage devices to allow transfer of data and programs between machines and to PCs.

Bluetooth dongle would be a nice to have. It would provide another way to transfer files easily enough.

Keyboard, mouse or touch/track pad? Seems like overkill for a calculator with decent in built keyboard. A track pad would allow graphical input but I'm not sure how or what use that would be. All would fall into the category of why not just use a PC instead.

Printers seem popular at the moment and supporting a number of USB printers would be neat but the driver requirements are likely to be excessive.

Network adapter or 802.11 adaptor -- again they seem like a bit of overkill and drivers will be a problem. Removable storage and/or bluetooth would be as good.

Video adapter? Might be useful but overkill, driver issues and why not use a PC instead.

Serial or parallel adaptors would allow control of external devices, so possibly useful to some but not to me.

So I'll say removable storage and then perhaps bluetooth.

Although, with PC connectivity both seem pretty minor.

- Pauli


+1 for removable storage :-)


The storage device is going to be a MicroSD card. Since the USB connector is a USB MicroAB connector, it wouldn't be possible to plug a USB flash drive in without an adapter, so I don't plan on writing any firmware support for USB storage.

Bluetooth and 802.11n require a huge amount of firmware, so I'm not likely to write that either.

Of course, there won't be anything to prevent someone else from writing firmware to support these.

Richard Ottosen and I originally intended to support the 82440A/B IR printers, and earlier prototypes had an IR emitter, but more recently due to the discontinuation of the printer we dropped it from our plan. However, we weren't aware of how much more efficient the IR emitters available today are as compared to those from the mid-1980s. Since Katie posted her results of getting decent range with only 4 mA drive, Richard and I are reconsidering putting the IR emitter back into the DIY5.


A/D converter with programmable ranges. Then all you need is the appropriate sensor. I do not know of any currently available devices.


I second an external A-to-D which would greatly expand the uses of the machine and is something I have been waiting for HP to implement. I am also willing to help with hardware/software development of such an option.


HP already does make something like that, the HP StreamSmart 400.

It connects to the calculator via a serial cable; for a hypothetical calculator that can use a USB interface to data acquisition and control hardware, it should be possible to offer a more powerful device.


Something like THIS ?

Not programmable, but the price is right: $29. I have their older RS-232 model, and it is quite fun to play with.

These guys also sell all sorts of stand-alone USB data loggers. I have one of their temperature ones - again, fun to play with. It will log temperature for several days. They normally delog to your PC, but I suppose you could get them to talk to a calculator.


That is remarkably inexpensive. Granted, there's not that much electronics inside, but still, I'd ordinarily expect to see that sell for a lot more.

I think it should be possible to get that particular product working with a calculator with a serial port, but regrettably I don't presently have time to spend on such an endeavor.


The primary use case would be device to device communication.


Because it has been mentioned in the forums before, that was already on my list. What kind of user interface would you envision for this capability?


Make all data transfer symmetric as it is done with the WP 34S so it doesn't change when you connect it to a PC or to another device.


My #1 choice would be an interface converter from USB to HP-IL. With this solution there would be something for everyone and a full range of HP peripherals ready for use. And perhaps -just perhaps- there would be some new IL-devices developed in the future. Yes, I'm dreaming but sometimes dreams come true like the 15C LE. So: Long live HP-IL! (maybe it helps ;-)




It might be possible to use the USB version of the PIL-Box with the sort of calculator I'm envisioning, depending on how much current the PIL-Box draws from the USB. The USB OTG port I'm envisioning may be quite limited with regard to how much power it can provide to the USB device.

However, if external power is somehow supplied to the PIL-Box, then the limitations of the USB OTG power from the calculator can be avoided.


Thanks for all the input! No pun intended. :-)


Connecting some hardware offering digital and analog (0..10V) I/O would be nice. A calculator like a (faster and USB-powered) 48G would make up for a great and inexpensive instrumentation and control device along with such hardware. I have small scale building control in mind.


For a calculator acting as a USB OTG host to control a device providing analog and digital I/O as you suggest, the calculator has to provide power over the USB port, even if the device is self-powered and doesn't actually need power from the USB port. In that scenario it isn't possible to power the calculator from USB.

The calculator can be powered from USB when it is acting as a USB device, rather than a host.

One way around that would be for the box that provides the analog and digital I/O to be a USB host rather than a USB device. Then the calculator would be in USB device mode, and the box could provide power to the calculator. However, that makes the calculator firmware substantially more complicated, and I don't have any plan to write anything like that. On the other hand, that's exactly what the Android Open Accessory Development Kit (ADK) does, so perhaps it's worth investigating further.

Possibly Related Threads…
Thread Author Replies Views Last Post
  HP-41 module covers and side port cover Nate Martin 1 1,533 12-02-2013, 01:51 AM
Last Post: Giancarlo
  Gathering USB dumps for Connectivity Kit <-> 39gII communication... debrouxl 2 1,662 12-01-2013, 12:59 PM
Last Post: Marcus von Cube, Germany
  HP 67 clear cases Keith Midson 7 2,611 10-14-2013, 11:05 AM
Last Post: Kiyoshi Akima
  Yet another benchmark port on the wiki: Savage Pier Aiello 35 9,534 09-26-2013, 03:22 AM
Last Post: Pier Aiello
  USB flashing/Li-po boards patryk 6 2,443 09-08-2013, 12:31 PM
Last Post: patryk
  USB Chargers for HP calcs Matt Agajanian 3 1,549 08-18-2013, 10:58 PM
Last Post: Craig Ruff
  HP 50G serial port programming Chris Smith 2 1,397 06-15-2013, 02:47 PM
Last Post: Chris Smith
  hp 49g+ and 50g cases William L. Drylie 16 4,567 06-04-2013, 07:28 PM
Last Post: Iqbal
  OT: RPN port to Casio fx-cg10/20? Matt Kernal 4 1,953 04-30-2013, 12:16 PM
Last Post: hugh steers
  USB vs DVD Han 9 2,882 04-19-2013, 06:05 PM
Last Post: Robert Prosperi

Forum Jump: