HP Forum Archive 20

[ Return to Index | Top of Index ]

opening HP 30B Message #1 Posted by Harald on 25 Feb 2012, 6:01 p.m. Today I received my HP-30B and also the keyboard overlays. (Thanks Eric!) The cable seems to take a little longer to get here though. So I thought I'd have a look inside the calculater and maybe just connect the RS232 myself (yes, I am a bit impatient). I assume all I need is levelshifting to 3.3V on the RXD and TXD line. But so far I haven't even managed to open the calculator. I have unscrewed the 5 bolts but still can't figure out what to do next. Could someone enlighten me please? Cheers, Harald

Re: opening HP 30B Message #2 Posted by Marcus von Cube, Germany on 25 Feb 2012, 7:23 p.m., in response to message #1 by Harald Pry it apart from the side by slightly bending the grey (softer) plastic. Get yourself an FTDI RS232-TTL 3V3 cable. You can wire it directly to the pads. You will need a way to connect the erase pin to Vdd in order to activate the SAM-BA boot loader (by clearing the flash completely). Reset is available through a hole on the back.

Re: opening HP 30B Message #3 Posted by Harald on 26 Feb 2012, 5:50 a.m., in response to message #2 by Marcus von Cube, Germany Thanks Marcus, that worked. Got it open now. While I have it open, is it worth adding a crystal? Does that help with any functionality other than communication (I probably won't need that, so I am not too bothered)? I like your idea of adding a 3.5mm connector to the calculator, but unfortunately can't work out a solution that is a bit easier on the eye ;) Cheers, Harald Edited: 26 Feb 2012, 8:11 a.m. after one or more responses were posted

Re: opening HP 30B Message #4 Posted by pascal_meheut on 26 Feb 2012, 5:58 a.m., in response to message #3 by Harald Adding a crystal helps a lot with communication and with the STOPWATCH function. If you don't use them, don't bother. Soldering the capacitors is not obvious.

Re: opening HP 30B Message #5 Posted by Harald on 26 Feb 2012, 6:16 a.m., in response to message #4 by pascal_meheut A stopwatch sounds like a nice feature to have. So I think I will do the modification. Soldering the caps is no problem. After all they are the large 0603s and not 0402s ;) The crystal seems to be more of a problem - I haven't got one and need to order one -> more waiting :( Cheers, Harald

What does the Erase Button on the HP cable do? Message #6 Posted by Harald on 26 Feb 2012, 8:01 a.m., in response to message #2 by Marcus von Cube, Germany I think I figured out how to connect everything appart from the "Erase" button. I belive the pinout on the flash connector to be: J31: Vcc (3V) J32: reset J33: TxD J34: RxD J35: GND J36: erase??? Is that correct so far? Does the "erase" button pull up J36 to Vcc like "reset" pulls up J32? I bet the cable arrives by the time I worked all this out... Cheers, Harald

Re: What does the Erase Button on the HP cable do? Message #7 Posted by Marcus von Cube, Germany on 26 Feb 2012, 9:07 a.m., in response to message #6 by Harald Erase needs to be pulled high to do an erase. The calculator needs to run for this to work. Just press the ON key to wake it up with ERASE pulled high. (I had accidentally written Vdd which is wrong.) The SDK mentioned here contains schematics.

[ Return to Index | Top of Index ]

Go back to the main exhibit hall