Re: HP12c repurposing project



#8

[Reviving this thread..]

Posted by TomL on 4 June 2010, 8:29 p.m.:

Quote:
I read about the repurposing project for the HP12c and was wondering if anyone has updates?

I'd rummaged around there about a year or so ago
with interest to see that move forward. I'm curious
what may have throttled the effort?

Posted by Katie Wasserman on 5 June 2010, 12:31 a.m.:

Quote:
The 20b SDK won't work on the 12C+, only the CPU is the same the peripherals are all different, but there is an SDK of sorts (sample program actually) for the 12C+

I thought the 12c+ was designed around an AT91SAM7L128
(maybe ~L64) COB, is that correct? If true there isn't
much in the way of 12c+ specific peripherals aside from
the keyboard matrix and the LCD controller on ports A and B.
Shouldn't be too difficult to puzzle out the interconnect.
The key matrix can be mapped with a scan of port C, the
LCD with a scan of A & B. I have a disembodied 12c+
LCD glass which I'd be willing to map out to help the
effort.

Or am I missing some subtle design caveat here for the
12c+?

Posted by Katie Wasserman on 5 June 2010, 12:38 a.m.:

Quote:
Pogo pins are pretty easy to find maybe even in 2 x 3 arrangements. But unless you can create some sort of locking plug it's going to be hard to hold the connector in place while programming.

Unfortunately the 12c+ 2x3 contact grid is on 2mm centers.
At least last time I rummaged for metric pitch pogos I
didn't get anywhere as most are 100mil pitch which
even if disassembled didn't look conducive to relocating
on a 2mm pitch. I just saw MillMax has 50mil pitch pogos
which could be made to work. But I'd only do so if I
really needed a stand-alone connector which could lock
to the keys molded in the housing. Even then you'd have a
rather awkward package if you were planing on using the
keyboard.

I'd probably just build a horizontal fixture and use stainless
steel spring wire bent into a long "L" shape as contacts.
That will give enough contact tension to make a reliable
connection and the calculator would be able to sit at a
low profile.

Posted by Scott Newell on 5 June 2010, 1:40 a.m.:

Quote:
If I was to build a fixture or cable from scratch, I'd seriously consider using the PC's serial port handshake lines to control the erase and reset pins... If only you could hit the on key through the cable, the whole programming process could be automated.

Is there anything needed to program flash besides communicating
with the SAM-BA via the DBGU port? From my scan of the AT91SAM7L
manual it appears the rom provides all needed functionality.

I have a bunch of AT91SAM7L128 samples lying around which I
was planning to use. But if a 12c+ doesn't have a functionally
modified AT91SAM7 use of that package is faster (and cheaper)
than creating a throw away board layout.

Thanks!


#9

Quote:
I thought the 12c+ was designed around an AT91SAM7L128 (maybe ~L64) COB, is that correct? If true there isn't much in the way of 12c+ specific peripherals aside from the keyboard matrix and the LCD controller on ports A and B. Shouldn't be too difficult to puzzle out the interconnect. The key matrix can be mapped with a scan of port C, the LCD with a scan of A & B. I have a disembodied 12c+ LCD glass which I'd be willing to map out to help the effort.

You're correct. The 12C+ has the same AT91SAM7L128 processor as the 20b/30b. There's no need to map out the keyboard nor LCD as Cyrille can supply code that does this -- it's like the SDK for the 20b with a sample 4-banger, integer calculator in c/c++.


Quote:
Is there anything needed to program flash besides communicating with the SAM-BA via the DBGU port? From my scan of the AT91SAM7L manual it appears the rom provides all needed functionality.

Nothing except for serial port level translation.


Quote:
I'm curious what may have throttled the effort?

I'm not sure who else is experimenting with this. I was able to get some simple stuff working but haven't found the time to develop the code I envisioned for this platform. Also the 30b was released that gave me a fast-running scientific programmable with re-assignable keys, one of the tings I was planning for a modified 12c+.

-Katie


#10

Quote:
There's no need to map out the keyboard nor LCD as Cyrille can supply code that does this -- it's like the SDK for the 20b with a sample 4-banger, integer calculator in c/c++

Any suggestion how/where to obtain this? I tried to dig up recent
mail from Cyrille to get a PM link but without success.

Thanks.

#11

Quote:
I'm not sure who else is experimenting with this. I was able to get some simple stuff working but haven't found the time to develop the code I envisioned for this platform.

Any idea where the serial number sequence started
corresponding to the 12C/arm7 ? I have a CNAxxxxyyyy
arm7 here and thought the CNA s/n prefix may be a
reliable indicator but I've also seen single CR2030
cell 12Cs with a CNA s/n prefix. So I'm at a loss.

Edited: 26 Oct 2010, 6:20 p.m.

#12

Quote:
I'd probably just build a horizontal fixture and use stainless steel spring wire bent into a long "L" shape as contacts. That will give enough contact tension to make a reliable connection and the calculator would be able to sit at a low profile.

This is what I was getting at:

http://www.third-harmonic.com/projects/voyager/12c/arm7-connector.pdf

It looks far more complex than it actually is, since I wanted
to document the dimensions accurately.

Armed with the SS wire, some scrap ABS, and minimal tooling
this could be hand built in an hour or two. The goal is to
bring out the contact tails to a more accommodating pitch
(eg: 2mm or 100mil) and continue on with a standard connector.

Interestingly enough a hybrid approach is possible utilizing
the existing battery cover. Unfortunately this is frustrated
to some extent due to the cover seating via sliding. One
would need to unload the pins beforehand and release them
once the cover is seated to play correctly. Certainly possible
though consuming a battery cover isn't my first choice.

NB: the 12C connector pinout signal definitions were taken from
the 20B schematic and some rudimentary probing of an actual
12c/arm7. I couldn't find a 12c/arm7 schematic and was making
a leap of faith HP didn't have cause to reinvent the connector
pinout. If a 12C/ARM7 schematic does exist I'd appreciate a
pointer.

Thanks.


#13

I can confirm that the 12C+ pinouts on the ARM serial connection pads are identical to the ones on the 20b/30b.

#14

You can always just send me an email and get a cable . . .

TW


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