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'[PIC]: Modem suggestions'
2000\10\30@072756 by Bob Ammerman

picon face
PCI is _much_ more complicated than ISA.

I'd avoid this like a plague!


----- Original Message -----
From: Alan B. Pearce <spam_OUTA.B.PearceTakeThisOuTspamRL.AC.UK>
To: <.....PICLISTKILLspamspam@spam@MITVMA.MIT.EDU>
Sent: Monday, October 30, 2000 3:52 AM
Subject: Re: Modem suggestions


>Anyone tried interfacing a PIC to the PCI bus?

I think I would only try this after reverse engineering the software for
your winmodem of choice. That seems to be all that is available these days
for PCI bus.

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2000\10\30@120423 by Harold M Hallikainen

picon face
On Mon, 30 Oct 2000 06:58:27 -0500 Bob Ammerman <RAMMERMANspamKILLspamPRODIGY.NET>
writes:
> PCI is _much_ more complicated than ISA.
>
> I'd avoid this like a plague!
>

       And since ISA stuff is going away, we're stuck with expensive chipsets
or modules when we want to integrate a modem into our product...

Harold


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2000\10\30@122300 by Dan Michaels

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Harold Hallikainen wrote:
>On Mon, 30 Oct 2000 06:58:27 -0500 Bob Ammerman <.....RAMMERMANKILLspamspam.....PRODIGY.NET>
>writes:
>> PCI is _much_ more complicated than ISA.
>>
>> I'd avoid this like a plague!
>>
>
>        And since ISA stuff is going away, we're stuck with expensive chipsets
>or modules when we want to integrate a modem into our product...
>


Several people have bad-mouthed the idea, but what the heck is the
big problem with interfacing the PIC with an "external" modem?

They are more expensive than internal, and probably are "not" going
to go away in the near future, but this sure sounds 100X easier to
deal with than trying to tap an ISA or PCI bus edge connector.
RS-232 channel plus 2 or 3 handshakes. ???????????????

- danM

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2000\10\30@130430 by Dale Botkin

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On Mon, 30 Oct 2000, Dan Michaels wrote:

{Quote hidden}

External modems are getting pretty pricey if bought new, last I checked.
If you're using used modems, there are issues with getting enough the same
make/model/rev level to respond predictably.  In my case, I find the app
will most likely result in a bunch of different modem types, which means
coming up with an init string for each one.  Plus you have an external
device under its own power, doing its own thing...  the code required to
do error detection and handling, try to reset the modem, etc is very
expensive in terms of program memory.

I've also had many, many instances of standalone modems needing to be
power cycled to get them out of a non-responsive hung condition.  Without
a lot of board space and components devoted to controlling the power to
the external modem (which may be AC or DC, either polarity, any of
several different connector styles which manufacturers change at whim,
etc) you stand a good chance of ending up with a unit in a useless state
needing manual intervention, in my case at a very remote location
requiring a lot of very expensive labor to reach.  And the worst part --
no way to detect that the remote is down without polling frequently, which
is simply not an option at 250 long distance calls a couple of times a
day.

So those are my reasons for not liking to use standalone modems, at least
the main ones.  If this were a onesie-twosie hobby project or had an
unlimited budget, yeah, buy a new external modem, write the code for that
modem, all's well.  This is for a larger project, though, with cost
constraints and deployment in remote areas.

Dale
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2000\10\30@134405 by Dan Michaels

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Dale Botkin wrote:

>External modems are getting pretty pricey if bought new, last I checked.
>If you're using used modems, there are issues with getting enough the same
>make/model/rev level to respond predictably.  In my case, I find the app
>will most likely result in a bunch of different modem types, which means
>coming up with an init string for each one.  Plus you have an external
>device under its own power, doing its own thing...  the code required to
>do error detection and handling, try to reset the modem, etc is very
>expensive in terms of program memory.
>

I would think that pretty much everything you mentioned here pertains
to internal ISA/PCI modems, as well as external - except h.w. reset,
which could be done with a relay, and one power supply for both PIC and
modem.

So I guess in your project you're going towards full integration rather
than tapping a PC-internal job. Problem here of course, is modem chips/DAA
modules cost so much more than any kind of commodity PC jobs - esp to get
anything approaching 56 kpbs. Would be interesting to hear what you
finally decide on.

- danM

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2000\10\30@142308 by Bob Ammerman

picon face
Negatives for external modems:

-Size
-Power supply
-Two boxes
-"clunkiness"
-Room for end users to goof things up
-Cost

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)

{Original Message removed}

2000\10\30@143943 by Dan Michaels

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face
Bob Ammerman wrote:
>Negatives for external modems:
>
>-Size
>-Power supply
>-Two boxes
>-"clunkiness"
>-Room for end users to goof things up
>-Cost
>


Negatives for internal modems:

-Size
-Power supply
-Two pcbs wired together
-"awkwardness"
-Pain-ina-butt interfacing to PCI or ISA bus
-Writing modem-specific s.w.
-Cost [cheap - only advantage I can see]


Negatives for integrating chip modems:

-Finding a chip <= 64-pin smt
-Writing "all" the s.w.
-Designing complex multi-layer pcb
-Designing complex analog-digital-filtering ckt
-Integrating DAA
-Getting FCC approval
-Cost [chips ain't cheap in < 100,000 qty]
-Cost [prohibitive when using available DAA modules]


Seems every route has its own personal set of problems.

- danM

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2000\10\30@144603 by Andrew Kunz

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Uh oh, Dan, we agree again.

As to Bob's "two boxes" and "power supply" I suggest that you get one bigger
box, bolt the external modem into it, and bolt the application board somwhere
else in the box.  Or maybe inside the modem, if there's room.

The power can be handled smartly by having the input jack from the wall wart
plug into the application board, which then draws its power from it and passes
the rest on to the modem.  If the original wall wart is incapable of supplying
adequate power, just get a bigger one instead.  Or you could charge a (internal)
battery and let the modem draw power from there when it needs to run the modem.

The modem, after all, only needs power when it's in use.

Andy









Dan Michaels <oricomspamspam_OUTUSWEST.NET> on 10/30/2000 02:39:43 PM

Please respond to pic microcontroller discussion list <@spam@PICLISTKILLspamspamMITVMA.MIT.EDU>








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cc:      (bcc: Andrew Kunz/TDI_NOTES)



Subject: Re: [PIC]: Modem suggestions








Bob Ammerman wrote:
{Quote hidden}

Negatives for internal modems:

-Size
-Power supply
-Two pcbs wired together
-"awkwardness"
-Pain-ina-butt interfacing to PCI or ISA bus
-Writing modem-specific s.w.
-Cost [cheap - only advantage I can see]


Negatives for integrating chip modems:

-Finding a chip <= 64-pin smt
-Writing "all" the s.w.
-Designing complex multi-layer pcb
-Designing complex analog-digital-filtering ckt
-Integrating DAA
-Getting FCC approval
-Cost [chips ain't cheap in < 100,000 qty]
-Cost [prohibitive when using available DAA modules]


Seems every route has its own personal set of problems.

- danM

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2000\10\30@145611 by David VanHorn

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So there is this external modem, which is specifically designed to do
credit card transactions, with a true bell 212 modem, which is what you
need for this.

It has a serial port, which you can easily connect to your system.

It has a display, keyboard, and card reader, but these can be enabled or
disabled as you like.

It's called a Tranz 330.

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2000\10\30@150641 by Alexey Vladimirov

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30 Oct 00, Dan Michaels writes to All:

P> Negatives for integrating chip modems:

P> -Finding a chip <= 64-pin smt
P> -Writing "all" the s.w.
P> -Designing complex multi-layer pcb
P> -Designing complex analog-digital-filtering ckt
P> -Integrating DAA
P> -Getting FCC approval
P> -Cost [chips ain't cheap in < 100,000 qty]
P> -Cost [prohibitive when using available DAA modules]

Did you check Si2400 from Silicon Labs ?
http://www.silabs.com/products/isomodem.asp
They have nice 2-chip solution (SOIC16) with integrated DAA, 3.3/5V 60 mW,
up to 2400 bit, check also Microchip Appnote AN731 for Si2400 application.
They quote $8.50 for chipset in 25000 quantity, it means about $15...$25 in
small qty.

If V.23 or Bell202 (1200 bit) will be enough for your project, you can find
another solution - software modem on the Scenix chip.
www.scenix.com/virtual/download/v23Kit.html
V.23 demo kit available for $89 from Monterrey Tools
Probably one can manufacture similar modem on SMD components
for the same $15...$25 in qty 100. And you will have some processor resources
left for another task...

P> Seems every route has its own personal set of problems.

For low-speed mid-volume and high-volume applications integrated modem seems
the most adequate solution.

>> Negatives for external modems:

>> -Size
>> -Power supply
>> -Two boxes
>> -"clunkiness"
>> -Room for end users to goof things up
>> -Cost

External modem will be the best solution, when you need several experimental
devices.

P> Negatives for internal modems:

P> -Size
P> -Power supply
P> -Two pcbs wired together
P> -"awkwardness"
P> -Pain-ina-butt interfacing to PCI or ISA bus
P> -Writing modem-specific s.w.
P> -Cost [cheap - only advantage I can see]

Possible application for internal modems - cheap multiport router under Linux -
put 4 modems into old desktop with 486 processor, 8/16 meg and small hard drive
and run Linux on it - it can be the cheapest solution for 4-port dial-up
server. However, it is not so reliable, as Cisco router, but works OK for
beginners. I know many internet providers, who start from this solution... You
can also found this solutions working today in some not so advanced
countries...
I am not sure, that internal ISA or PCI modems can be used successfully in
embedded applications.

Best regards

Alexey

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2000\10\30@152310 by Dale Botkin

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On Mon, 30 Oct 2000, Dan Michaels wrote:

> Dale Botkin wrote:
>
> >External modems are getting pretty pricey if bought new, last I checked.
> >If you're using used modems, there are issues with getting enough the same
> >make/model/rev level to respond predictably.  In my case, I find the app
> >will most likely result in a bunch of different modem types, which means
> >coming up with an init string for each one.  Plus you have an external
> >device under its own power, doing its own thing...  the code required to
> >do error detection and handling, try to reset the modem, etc is very
> >expensive in terms of program memory.
> >
>
> I would think that pretty much everything you mentioned here pertains
> to internal ISA/PCI modems, as well as external - except h.w. reset,
> which could be done with a relay, and one power supply for both PIC and
> modem.

To some degree, yes.  The difference is that I *could* easily control
power and therefore the known state of an ISA modem.  Either ISA or PCI is
pretty much out for this project, though, as I don't have six months to
figure out how to interface with PCI and don'thave enough spare I/O pins
for either.

> So I guess in your project you're going towards full integration rather
> than tapping a PC-internal job. Problem here of course, is modem chips/DAA
> modules cost so much more than any kind of commodity PC jobs - esp to get
> anything approaching 56 kpbs. Would be interesting to hear what you
> finally decide on.

Well, I would if I could get any manufacturers to sell integrated modems
in small quantities, or a distributor who had anything for a reasonable
price.  I've had several people poitn out really nice looking modem
chipsets that would be great if I were planning to build a few thousand
units, but if it doesn't have a low cost, low volume US distributor I
can't use it right now.

I don't need anything even remotely approaching 56K, in fact I would
prefer a 212A modem.  I've not seen a 1200 connection fail for a long
time, but V.90 sucks for reliability on anything but clean lines.
Remember this is a PIC driving it, not me sitting at the keyboard knowing
that the supposed 40K connection is useless when it doesn't respond.
These things will dial in once in a great while and send a couple of lines
of text, so even 1200 is overkill.  300 would do.

I'm trying one more time to get a response out of Cermetek, since the
others seem to be two to three times more expensive and way out of budget
for this.  Mean time, I'm rewriting the modem handler to be much, much
more generic, and thinking seriously about an external power control relay
for the PIC to be able to power-cycle an external modem.

Dale
---
The most exciting phrase to hear in science, the one that heralds new
discoveries, is not "Eureka!" (I found it!) but "That's funny ..."
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2000\10\30@152855 by Dale Botkin

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On Mon, 30 Oct 2000, Dan Michaels wrote:

> Seems every route has its own personal set of problems.

Ain't THAT the truth!!!  I'm beginning to question the wisdon of tkaing on
this project.  Seemed so simple at the time!  I think I'm about a forty
hours further into this than I planned...  but I'm learning a WHOLE lot.

I suspect I'll end up with a very fine general purpose modem driver .h
file written for CCS C, made as generic as humanly possible, that will do
what's needed with just about any Rockwell or USR based modem.  When I
arrive at that happy point I will, of course, share the code.

Dale
---
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discoveries, is not "Eureka!" (I found it!) but "That's funny ..."
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2000\10\30@153309 by David VanHorn

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>
>I don't need anything even remotely approaching 56K, in fact I would
>prefer a 212A modem.  I've not seen a 1200 connection fail for a long
>time, but V.90 sucks for reliability on anything but clean lines.
>Remember this is a PIC driving it, not me sitting at the keyboard knowing
>that the supposed 40K connection is useless when it doesn't respond.
>These things will dial in once in a great while and send a couple of lines
>of text, so even 1200 is overkill.  300 would do.

If you're doing credit card transactions, anything other than a 212a modem
will just slow them down. The hosts are still 212A because the call
establishment of the higher speed modes takes too long.

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2000\10\30@154534 by Dale Botkin

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On Mon, 30 Oct 2000, David VanHorn wrote:

> So there is this external modem, which is specifically designed to do
> credit card transactions, with a true bell 212 modem, which is what you
> need for this.
>
> It has a serial port, which you can easily connect to your system.
>
> It has a display, keyboard, and card reader, but these can be enabled or
> disabled as you like.
>
> It's called a Tranz 330.

Yes, but I could buy Cermetek or Xecom integrated modems cheaper from an
inflated distributor. Even used Verifone units go for $50 and up, usually
over $100, from what I have seen -- unless you know where a bunch could be
had in the $30-40 range?  That's where we need to be.

Dale
---
The most exciting phrase to hear in science, the one that heralds new
discoveries, is not "Eureka!" (I found it!) but "That's funny ..."
               -- Isaac Asimov

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2000\10\30@154948 by Scott Newell

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>pretty much out for this project, though, as I don't have six months to
>figure out how to interface with PCI and don'thave enough spare I/O pins

It seems to me the real downside to the PCI modem isn't the interface
(which is in itself non-trivial), it's the host processing.  If they
require a Pentium or better to run the modem DSP drivers, you're not gonna
come anywhere close with a PIC.


newell

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2000\10\30@154953 by Dale Botkin

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On Mon, 30 Oct 2000, Alexey Vladimirov wrote:

> Did you check Si2400 from Silicon Labs ?
> http://www.silabs.com/products/isomodem.asp
> They have nice 2-chip solution (SOIC16) with integrated DAA, 3.3/5V 60 mW,
> up to 2400 bit, check also Microchip Appnote AN731 for Si2400 application.
> They quote $8.50 for chipset in 25000 quantity, it means about $15...$25 in
> small qty.

> If V.23 or Bell202 (1200 bit) will be enough for your project, you can find
> another solution - software modem on the Scenix chip.
> www.scenix.com/virtual/download/v23Kit.html
> V.23 demo kit available for $89 from Monterrey Tools
> Probably one can manufacture similar modem on SMD components
> for the same $15...$25 in qty 100. And you will have some processor resources
> left for another task...

And either way I get to design and FCC certify a new modem.  That's why I
was looking to Cermetek or similar products, or a standalone unit.  I
don't want to try to design and build a line interface for this project,
it's not my area of expertise.

Dale
---
The most exciting phrase to hear in science, the one that heralds new
discoveries, is not "Eureka!" (I found it!) but "That's funny ..."
               -- Isaac Asimov

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2000\10\30@163520 by David VanHorn

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>
>Yes, but I could buy Cermetek or Xecom integrated modems cheaper from an
>inflated distributor. Even used Verifone units go for $50 and up, usually
>over $100, from what I have seen -- unless you know where a bunch could be
>had in the $30-40 range?  That's where we need to be.

Try Automated Transactions in California.

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2000\10\30@175403 by Bill Westfield

face picon face
    unless you know where a bunch could be
   had in the $30-40 range?  That's where we need to be.

Customers for embedded products (and the developers too) need to be aware
that you just don't GET the same economies of scale in an embedded system
as you would in a "commodity" PC.  Just because you can get a PC modem,
ethernet, USB, or other IO card for $30 doesn't mean that you can put the
same sort of functionality into a non-commodity platform for the same price.
Even if your platform is a PC, you're faced with any particular technology
going in&out of "commodity" status very quickly.  (for example, "thinnnet"
ethernet boards are getting hard to find...)

You might want to look into some PCMCIA modems (which will hopefully outlive
the ISA bus by a bit.)  Don't some PCMCIA modems essentially bypass most of
the PCMCIA bus and just sit off a serial port?  Also, perhaps internal
modems aimed at mac or older PC laptops might be useful.

BillW

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2000\10\30@223835 by dre Domingos F. Souza

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>Several people have bad-mouthed the idea, but what the heck is the
>big problem with interfacing the PIC with an "external" modem?
>They are more expensive than internal, and probably are "not" going
>to go away in the near future, but this sure sounds 100X easier to
>deal with than trying to tap an ISA or PCI bus edge connector.
>RS-232 channel plus 2 or 3 handshakes. ???????????????

       Hey, why use an ISA modem? Gather a RC2496 from Rockwell and some glue logic. http://www.ustr.com has some nice info on it


--------------8<-------Corte aqui-------8<--------------

       All the best!!!
       Alexandre Souza
       RemoveMExandinhoTakeThisOuTspaminterlink.com.br

--------------8<-------Corte aqui-------8<--------------

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'[PIC]: Modem suggestions'
2000\11\01@142955 by Peter L. Peres
picon face
>And since ISA stuff is going away, we're stuck with expensive chipsets or
>modules when we want to integrate a modem into our product...
>
>Harold

I have looked at external modems (serial) and at PCMCIA modems. The first
is easy, the second is a good choice if you already need to support an IDE
or CF card. I doubt whether I would try to do it with a PIC though (I do
not use the larger PIC series).

Peter

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2000\11\01@143005 by Peter L. Peres

picon face
>for this.  Mean time, I'm rewriting the modem handler to be much, much
>more generic, and thinking seriously about an external power control relay
>for the PIC to be able to power-cycle an external modem.

If you have an external modem and level translators then you can implement
a modem power switch using the BREAK condition on TxD. It'a a simple RC
combination driving a bipolar transistor. I did this a long time ago,
using two transistors and a relay. It steals power from the modem wall
wart and the relay cuts the power to the modem after the circuit.  The two
transistors implement a standard Schmitt Trigger taken from a book. You
can use a monoflop instead with a 555 or such. This works with any
computer not just PICs. Set BREAK for 1 second - hop the modem is off. You
can leave the line in the BREAK state forever to avoid the modem taking
power (and answering the phone or bugging the lines if it is electrically
'crazy' if you use the second pair of relay contacts to separate the phone
line). This solution was used in a modem pool (many modems) where a hanged
modem usually meant service on Sunday.

Peter

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2000\11\01@182614 by Dale Botkin

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On Wed, 1 Nov 2000, Peter L. Peres wrote:

> >for this.  Mean time, I'm rewriting the modem handler to be much, much
> >more generic, and thinking seriously about an external power control relay
> >for the PIC to be able to power-cycle an external modem.
>
> If you have an external modem and level translators then you can implement
> a modem power switch using the BREAK condition on TxD. It'a a simple RC
> combination driving a bipolar transistor. I did this a long time ago,
> using two transistors and a relay. It steals power from the modem wall
> wart and the relay cuts the power to the modem after the circuit.  The two
> transistors implement a standard Schmitt Trigger taken from a book. You
> can use a monoflop instead with a 555 or such. This works with any
> computer not just PICs. Set BREAK for 1 second - hop the modem is off. You
> can leave the line in the BREAK state forever to avoid the modem taking
> power (and answering the phone or bugging the lines if it is electrically
> 'crazy' if you use the second pair of relay contacts to separate the phone
> line). This solution was used in a modem pool (many modems) where a hanged
> modem usually meant service on Sunday.
>

Now, there's a good idea.  I could use a 4PST relay to shut off the modem
*and* disconnect it from the phone line when not in use, thus preventing
99.999% of the modem-destroying phone line transients as well!  What a
great idea.

Dale
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The most exciting phrase to hear in science, the one that heralds new
discoveries, is not "Eureka!" (I found it!) but "That's funny ..."
               -- Isaac Asimov

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2000\11\05@202541 by Andy Howard
picon face
----- Original Message -----
From: "William Chops Westfield" <billwEraseMEspam.....CISCO.COM>
To: <EraseMEPICLISTspamMITVMA.MIT.EDU>
Sent: Monday, October 30, 2000 10:52 PM
Subject: Re: [PIC]: Modem suggestions



> You might want to look into some PCMCIA modems (which will hopefully
outlive
> the ISA bus by a bit.)  Don't some PCMCIA modems essentially bypass most
of
> the PCMCIA bus and just sit off a serial port?  Also, perhaps internal
> modems aimed at mac or older PC laptops might be useful.



Does anyone have any experience of using a PCMCIA modem with a
microcontroller?  Can it be done without implementing the whole card/socket
services shebang?  If so it could save a lot of messing around with external
modems which, because of the painful telecom approval procedures over here,
is often the "best" solution for low volume products.







.

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2000\11\05@205708 by Bob Ammerman

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PCMCIA bus is _very_ similar to ISA bus.

You don't need too much at all to talk to a PCMCIA modem. Certainly not a
full-blown card and socket services. In the early days of PCMCIA many cards
came with a 'point enabler' which basically would turn on the card so that
it would appear, effectively, on the ISA bus. At that point you could talk
to it just like an ISA modem.

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)

{Original Message removed}

2000\11\06@075514 by mike

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face
On Mon, 6 Nov 2000 01:20:51 -0000, you wrote:

>----- Original Message -----
>From: "William Chops Westfield" <RemoveMEbillwEraseMEspamEraseMECISCO.COM>
>To: <RemoveMEPICLISTspam_OUTspamKILLspamMITVMA.MIT.EDU>
>Sent: Monday, October 30, 2000 10:52 PM
>Subject: Re: [PIC]: Modem suggestions
>
>
>
>> You might want to look into some PCMCIA modems (which will hopefully
>outlive
>> the ISA bus by a bit.)  Don't some PCMCIA modems essentially bypass most
>of
>> the PCMCIA bus and just sit off a serial port?  Also, perhaps internal
>> modems aimed at mac or older PC laptops might be useful.
>
Yes - with most PCMCIA modems you are effectively talking to a
16550-style uart with a hayes-type modem connected to it. About the
only part of the PCMCIA spec you need to know is the pinout! Almost
all of the card/socket services stuff is to do with mapping the card
into the host machine and so is not required for a MCU application.
Unfortunately you won't be able to get at the serial part directly (in
modern modems this probably doesn't physically exist), but talking to
the uart should not be at all difficult.   One minor caveat, though - don't assume that a simple interface will
necessarily work with ALL PCMCIA modems - there may be some that are
implemented differently. This should not be a major problem - just be
sure to test any modems you plan to use, and don't let users plug just
any old modem in and expect them to work.

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2000\11\06@080132 by Michael Rigby-Jones

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{Quote hidden}

There are also Winmodems available in PCMCIA form.  I have an IBM
10BaseT/V90 Modem which I had no end of trouble getting working.  I only
found out after extensive digging that it was a winmodem.  Needless to say,
not suitable for use with a PIC!

Mike

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