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'PIC <> modem chips'
1996\06\02@182645 by Wireless Scientific

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Folks,

Does anyone have something to say about single chip modems? I'm considering
putting a 2400bps modem chip on one of my PIC data acquisition boards but
would like some comments/suggestions/flames.

Thanks,
craig

1996\06\03@064410 by Kalle Pihlajasaari

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Hi,

> Does anyone have something to say about single chip modems? I'm considering
> putting a 2400bps modem chip on one of my PIC data acquisition boards but
> would like some comments/suggestions/flames.

I will assume you want to use a Telephone line modem.
Radio modems have similar tradeoffs though.

I have in the past found that the run of the mill pocket modem
that has a standard serial port works well.  I have used these
in remote applications with Basic Stamps without trouble.  Sending
the init string and such is all it takes with a serial port and you
can ignoore all the other pins by strapping them high.  Wait for the
DCD line to go high or the CONNECT string wait a few seconds and then
strat sending data.  Just to receive calls is easier, just wait for
your protocol packets from the host and let it do the call establishment
and hanging up.

Prices should be in the US$75 to US$200 range for a 2400 to 14400
modem  (if you have the space a full size external modem will be a bit
cheaper)  and you get all the DAA (data access arrangemet) isolation,
relays, ring detectors, &c.  And you can store the phone number in the
modem and change it without having to change your PIC/STAMP code.

Internal card modems are even cheaper and all you need is the idea
from the PIC compertition handbook where one of the entrants uses a
PIC to generate ISA bus signals (8 data, 3 address and IOR, IOW, RST)
with all the other signals fixed to the nominal levels, this will
require you to program the 8250/16450/16550 UART on the card directly
but this is quite simple with code in BIOS dissasemblies, IBM tech-refs,
PC interfacing books and also in the Startech UART data book (very
cheap 16550 UARTS, won't work on fast PCs though > AT bus speeds).

On the other hand using a modem chip requires all the analog hang on stuff
and you wont likely get FCC or Bell (Telco) approval unless you are
prepared to go through the type aproval schlep which will cost
quite a lot.

Volume will dictate.

Cheers
--
Kalle Pihlajasaari     spam_OUTkalleTakeThisOuTspamdata.co.za
Interface Products     Box 15775, Doornfontein, 2028, South Africa
+27 (11) 402-7750      Fax: +27 (11) 402-7751

1996\06\03@101055 by Wireless Scientific

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At 12:30 PM 6/3/96, Kalle Pihlajasaari wrote:
>Volume will dictate.

Kalle,

Yes, I'm planning for serious volume so an off the shelf modem is to pricy.
I'd like all connection hardware for about $20, which includes modem chip,
DAA and RJ stuff. My total package is about the size of a 9 volt battery.

>On the other hand using a modem chip requires all the analog hang on stuff
>and you wont likely get FCC or Bell (Telco) approval unless you are
>prepared to go through the type aproval schlep which will cost
>quite a lot.
>

I don't mind that, I've got a Ph.D. in analog and we go through FCC for all
of our spread spectrum radio products continually.

Thanks for your reply.
craig


{Quote hidden}

1996\06\04@000908 by Michael S. Hagberg

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I recently looked at modem chips and found that it is less expensive
to just use an external modem.  With the mass production of modems
I couldn't come close to the price. I just programmed my device to
use Hayse commands over a RS232 line.

Michael

1996\06\04@003341 by Wireless Scientific
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At 6:06 PM 6/3/96, Michael S. Hagberg wrote:
>I recently looked at modem chips and found that it is less expensive
>to just use an external modem.  With the mass production of modems
>I couldn't come close to the price. I just programmed my device to
>use Hayse commands over a RS232 line.

Michael,

I agree with your thoughts except I'm looking at possibly 10,000 (hopefully
more) devices with modem connectivity. These devices also need to small,
about the size of a 9 volt battery. I'll keep looking for modem chips.

craig

1996\06\05@104729 by Mike DeMetz

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>
> I agree with your thoughts except I'm looking at possibly 10,000 (hopefully
> more) devices with modem connectivity. These devices also need to small,
> about the size of a 9 volt battery. I'll keep looking for modem chips.
>
> craig
>
Have you checked XECOM's data book? All kinds of modem and telephone
interface modules, all FCC compliant. Examples:XE9624F,
2.28x1.08x.42 inch, 300/1200/2400 FAX/Data 200mW(5V),50mW in sleep
mode, RS232 interface and Tip/Ring. Others up to 28.8 v.34.
**********************************************************
*Mike DeMetz                      SYSCON International   *
*mikedspamKILLspamsyscon-intl.com            South Bend, IN USA     *
*aka .....73165.1230KILLspamspam.....compuserve.com    using Pegasus Mail     *
**********************************************************

1996\06\05@170102 by Wireless Scientific

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At 9:49 AM 6/5/96, Mike DeMetz wrote:
>>
>> I agree with your thoughts except I'm looking at possibly 10,000 (hopefully
>> more) devices with modem connectivity. These devices also need to small,
>> about the size of a 9 volt battery. I'll keep looking for modem chips.
>>
>> craig
>>
>Have you checked XECOM's data book? All kinds of modem and telephone
>interface modules, all FCC compliant. Examples:XE9624F,
>2.28x1.08x.42 inch, 300/1200/2400 FAX/Data 200mW(5V),50mW in sleep
>mode, RS232 interface and Tip/Ring. Others up to 28.8 v.34.
>**********************************************************
>*Mike DeMetz                      SYSCON International   *
>*EraseMEmikedspam_OUTspamTakeThisOuTsyscon-intl.com            South Bend, IN USA     *
>*aka 73165.1230spamspam_OUTcompuserve.com    using Pegasus Mail     *
>**********************************************************


Mike,

Thanks for the tip, I've ordered the XECOM book today.

craig

1996\06\06@175512 by Wireless Scientific

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At 9:49 AM 6/5/96, Mike DeMetz wrote:
>Have you checked XECOM's data book? All kinds of modem and telephone
>interface modules, all FCC compliant. Examples:XE9624F,
>2.28x1.08x.42 inch, 300/1200/2400 FAX/Data 200mW(5V),50mW in sleep
>mode, RS232 interface and Tip/Ring. Others up to 28.8 v.34.


FYI, I called XECOM and got some volume pricing.

               100     1000
XE1276 (1200)   69      49
XE2476 (2400)   78      54


Kind of pricey huh? Especially when you can't give away a 2400 modem.

craig

1996\06\07@090600 by Mike DeMetz

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> FYI, I called XECOM and got some volume pricing.
>
>                 100     1000
> XE1276 (1200)   69      49
> XE2476 (2400)   78      54
>
>
> Kind of pricey huh? Especially when you can't give away a 2400 modem.
>
Maybe one could find some PCMCIA or laptop modems cheap and take them
apart.
**********************************************************
*Mike DeMetz                      SYSCON International   *
*@spam@mikedKILLspamspamsyscon-intl.com            South Bend, IN USA     *
*aka KILLspam73165.1230KILLspamspamcompuserve.com    using Pegasus Mail     *
**********************************************************

1996\06\07@145931 by Juan Jose Abba

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Can somebody please send XECOM e-mail address
thanks in advance
juan


{Quote hidden}

1996\06\07@154324 by Eric Smith

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Craig of Wireless Scientific <TakeThisOuTwsciEraseMEspamspam_OUTNET-MAGIC.NET>
> FYI, I called XECOM and got some volume pricing.
...
> Kind of pricey huh? Especially when you can't give away a 2400 modem.

I don't mean to be rude, but why should the fact that the only good use for
an old 2400 bps modem is to throw it away imply that a manufacturer should
be willing to sell newly manufactured ones to you cheap?

By the same analogy, you should be able to buy brand new 40 MB disk drives
with warranty form Seagate for $4 to $6.

Cheers,
Eric

1996\06\07@160236 by Wireless Scientific

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At 12:37 PM 6/7/96, Eric Smith wrote:
>Craig of Wireless Scientific <RemoveMEwscispamTakeThisOuTNET-MAGIC.NET>
>> FYI, I called XECOM and got some volume pricing.
>...
>> Kind of pricey huh? Especially when you can't give away a 2400 modem.
>
>I don't mean to be rude, but why should the fact that the only good use for
>an old 2400 bps modem is to throw it away imply that a manufacturer should
>be willing to sell newly manufactured ones to you cheap?

I see your point. But as technology advances so should decreases in
pre-existing technology pricing (if hardware is still available). If this
is logical then why should a 2400 baud modem be more expensive that a
14400. If 2400 modem chips are not available, use a 14400 at 2400. The user
is not going to know.

In XECOM's case it's purely packaging, they've got a small product. But
they've priced themselves beyond the "smallness" utility.

craig

1996\06\07@162857 by John Payson

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>
> Craig of Wireless Scientific <wsciEraseMEspam.....NET-MAGIC.NET>
> > FYI, I called XECOM and got some volume pricing.
> ...
> > Kind of pricey huh? Especially when you can't give away a 2400 modem.
>
> I don't mean to be rude, but why should the fact that the only good use for
> an old 2400 bps modem is to throw it away imply that a manufacturer should
> be willing to sell newly manufactured ones to you cheap?
>
> By the same analogy, you should be able to buy brand new 40 MB disk drives
> with warranty form Seagate for $4 to $6.

Excellent point.  Another difference is that most embedded modem products
have an implied or contractual assurance that THE SAME PRODUCT will be
available for a significant length of time.  If you design a product to use
a PCMCIA modem instead, you may get a significant cost savings, BUT you may
end up pulling out your hair when your preferred modem is dropped and the
new one you get isn't "quite" compatible.

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