nurmi@haapana.tut.fi (Nurmi Jari) (11/09/89)
I am looking for a standard serial interface which could be implemented using 0-5V CMOS devices. I have heard some second hand information that there EXISTS some RS-232-xxx standard that might do. If someone out there knows such standard, please let me know! I would be pleased to have a) a verification of the existence of the 5V version b) the identification of the standard (by what name can I find it) and then c) what is the reference where I can read the specifications of it. Please save me a lot of work! Jari Nurmi # Tampere University of Technology # /Signal Processing Laboratory nurmi@tut.fi # PO Box 527, SF-33101 Tampere, Finland (nurmi@tut.UUCP mcvax!tut!nurmi)# tel: +358 31 162 697 fax: 162 913
henry@utzoo.uucp (Henry Spencer) (11/10/89)
In article <9820@etana.tut.fi> nurmi@tut.fi (Nurmi Jari) writes: >I am looking for a standard serial interface which could be implemented >using 0-5V CMOS devices... Well, the Maxim MAX232 family implements real RS232C using a +5 supply, and as I recall it's a CMOS device... It has its own voltage multiplier and inverter to turn +5 into +-9. This is by far the simplest and least painful solution unless you have special constraints. If "using 0-5V CMOS devices" means "on my own CMOS chip" or "with 4000-series chips only" or "with very low power consumption", then you do. Consider RS422, which is differential (2 wires per signal) but can be done with +5 only if my memory is correct. RS423 is sort of a modern RS232 using +-5. I can't think of any non-differential +5-only form offhand. Although the RS232 standard says (-3)-(+3) is the minimum swing, many RS232 receivers will react acceptably to a 0-3V swing. That's definitely non-standard, though. -- A bit of tolerance is worth a | Henry Spencer at U of Toronto Zoology megabyte of flaming. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
phil@ingr.com (Phil Johnson) (11/10/89)
In article <9820@etana.tut.fi> nurmi@tut.fi (Nurmi Jari) writes: > >I am looking for a standard serial interface which could be implemented >using 0-5V CMOS devices. I have heard some second hand information that >there EXISTS some RS-232-xxx standard that might do. > Maxim Integrated Products 120 San Gabriel Dr. Sunnyvale, California 94086 USA (408) 737-7600 Manufactures a series of RS-232 transceivers that use +5vdc only. There are about 20-30 different chips in the MAX 2xx series, each with a different number of drivers, receivers, external caps, and features. The RS-232 voltages (+- 10 vdc) are derived from a charge-pump circuit developed by Maxim. I have used these chips on several projects and it really saves time and space when you don't have to worry about an extra power supply just for the serial interface. (NOPE: I don't work for, receive compensation from, but use Maxim products) (If they would like to send me any sample I'll take them.) 8-{) -- Philip E. Johnson UUCP: usenet!ingr!b3!sys_7a!phil MY words, VOICE: (205) 772-2497 MY opinion!
josef@peun11.uucp (Moellers) (11/14/89)
nurmi@haapana.tut.fi (Nurmi Jari) writes: >I am looking for a standard serial interface which could be implemented >using 0-5V CMOS devices. I have heard some second hand information that >there EXISTS some RS-232-xxx standard that might do. >If someone out there knows such standard, please let me know! I would be >pleased to have a) a verification of the existence of the 5V version >b) the identification of the standard (by what name can I find it) and then >c) what is the reference where I can read the specifications of it. There are two ways to get away with 5V only: 1 Stick with the "original" RS232C (a.k.a. V.28) and use chips manufactured by Maxim: the MAX23x series chips. They incorporate a 5V to +-10V converter which works just fine. 2 Take the RS422 standard. It's a symmetric interface which uses two wires for each transmission line, but everything works with 5V. Josef Moellers | Nixdorf Computer AG USA: uunet!philabs!linus!nixbur!mollers.pad | Dept. DX-PC !USA: mcvax!unido!nixpbe!mollers.pad | Pontanusstrasse Phone: (+49) 5251 146245 | D-4790 Paderborn