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KenM
05-29-2005, 01:19 AM
Question to Parallax.

I assume that on the·BS2p, pe and px models, there are unused I/O pins, is that correct?

36 I/O pins on the SX48 package itself.
The Stamp modules have 16 general purpose I/O, and·3 pins for programing (SOUT, SIN, ATN).

How are the extra I/0 pins configured, are they left floating?

Thanks.

Ken

Chris Savage
05-29-2005, 01:36 AM
Ken,

·· This link should answer your question.· It is the schematic for the BS2p24.

http://www.parallax.com/dl/docs/prod/schem/Bs2p24SchemRevB.pdf



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Chris Savage
Parallax Tech Support
csavage@parallax.com (mailto:csavage@parallax.com)

Jon Williams
05-29-2005, 01:49 AM
On 24-pin "p"-family modules, pins are left as inputs and the internal pull-ups are activated to keep them in a known state.

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Jon Williams
Applications Engineer, Parallax

Chris Savage
05-29-2005, 01:53 AM
Thanks Jon,

·· I forgot to mention that since that's not in the schematic.

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Chris Savage
Parallax Tech Support
csavage@parallax.com (mailto:csavage@parallax.com)

Tracy Allen
05-29-2005, 02:07 AM
The extra 16 pins are configured as inputs with the internal weak pullups enabled, ttl levels.

The pins still respond to commands that address those pins. For example, if you issue the following:
AUXIO
LOW 5
OUTH=0

The 9 pins affected will in fact go low, and since the pullups are enabled, the current will increase ~9*Vdd/20kohms.

Even if you are not using the pins, the AUXIO DIRS and OUTS registers are available. If you leave DIRS as inputs, then you can use the OUTS register with impunity. If you mess with the DIRS register, remember that the pullups are active.

The BS2px has all the new configuration options for pins on MAINIO. Come to think of it, I don't know what will happen if you do an AUXIO, and then apply those configuration options. I guess that is another question for Parallax. If someone buys an OEM version of the 'px, will CONFIG and COMPARATOR work on AUXIO?

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Tracy Allen
www.emesystems.com (http://www.emesystems.com)

KenM
05-29-2005, 02:33 AM
Thanks for the answers....

So at my own risk (of course) I could void any and all warranty, solder to the unused pins and increase my I/O.

Not that I would do such a thing.....(so how much longer for the ~$10 SX board?)

P.S. was the answer to this question in any Parallax documentation? If yes, please don't point me to where, I need to look again.

Ken

KenM
05-29-2005, 02:36 AM
I believe COMPARITOR is available only on RA.1 & RA.2 RB1, & RB2, is that correct?
At least that is the case with the SX18 & 28.



Tracy Allen said...
I guess that is another question for Parallax. If someone buys an OEM version of the 'px, will CONFIG and COMPARATOR work on AUXIO?


Post Edited (KenM) : 5/28/2005 7:53:04 PM GMT

Jon Williams
05-29-2005, 03:29 AM
Ken,

I'm confused by your questions ... if you have an SX preprogrammed with the PBASIC interpreter core then you will not have access to the pins on RD and RE -- why void your warranty by soldering things to them.

The comparitor is actually on RB.1 and RB.2 -- on the BS2px it is P1 and P2, with P0 available to follow the comparitor output if so configured (see the help file under CONFIGPIN).

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Jon Williams
Applications Engineer, Parallax

KenM
05-29-2005, 03:59 AM
Jon,
What does the command AUXIO do on a BS2p?
I thought that enabled the unused pins...RD and RE.
I have no intention of soldering anything to a BS2p, as stated in my previous post. I will wait for the new SX board.

Jon Williams (Parallax) said...
Ken,
if you have an SX preprogrammed with the PBASIC interpreter core then you will not have access to the pins on RD and RE -- why void your warranty by soldering things to them.

Tracy Allen
05-29-2005, 04:18 AM
Oh, right the SX chip has the comparator function only on port B, so BS2px COMPARE can only work there.

On the other hand, AUXIO on a BS2p-24 and a BS2pe-24 lets you address the pins and yes, if you solder wires to them you can use them. (I've done it, but certainly don't recommend it.) In any case, you can use the DIRS and OUTS registers associated with those pins. You just have to remember that the pullups are always active, in either the input or the output state.

My question has to do with the BS2px, the effect of CONFIGPINS when AUXIO is selected. Level TTL/CMOS, pullups ON/OFF, and Schmitt ON/OFF and Direction IN/OUT are available on all the ports B-E. Is CONFIGPINS restricted to MAINIO, or is there stealth provision for a 40 pin version?

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Tracy Allen
www.emesystems.com (http://www.emesystems.com)

KenM
05-29-2005, 07:22 AM
Thanks for the update Tracy.

Ken Mathis (yes the same one)