Post by thread:PIC <> modem chips

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

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}>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 .....kalleKILLspam@spam@data.co.za >Interface Products Box 15775, Doornfontein, 2028, South Africa >+27 (11) 402-7750 Fax: +27 (11) 402-7751

> > 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 * *mikedKILLspamsyscon-intl.com South Bend, IN USA * *aka .....73165.1230KILLspam.....compuserve.com using Pegasus Mail * **********************************************************

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_OUTTakeThisOuTsyscon-intl.com South Bend, IN USA * >*aka 73165.1230spam_OUTcompuserve.com using Pegasus Mail * >********************************************************** Mike, Thanks for the tip, I've ordered the XECOM book today. craig

Can somebody please send XECOM e-mail address thanks in advance juan {Quote hidden}>> 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 * >*RemoveMEmikedTakeThisOuTsyscon-intl.com South Bend, IN USA * >*aka spamBeGone73165.1230spamBeGonecompuserve.com using Pegasus Mail * >********************************************************** > >

At 12:37 PM 6/7/96, Eric Smith wrote: >Craig of Wireless Scientific <RemoveMEwsciTakeThisOuTNET-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

> > Craig of Wireless Scientific <wsciEraseME.....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.