Date: Tue, 19 Feb 2002 15:51:43 +0800 From: Raymond <[EMAIL PROTECTED]> Subject: Re: [LIB] Some answers please?
At 06:12 PM 18/02/2002 -0800, you wrote: >Date: Mon, 18 Feb 2002 20:08:18 -0500 >From: "Pres Waterman" <[EMAIL PROTECTED]> >Subject: Re: [LIB] Some answers please? > >don't overclock it). What do you need to run off the serial port? It might >well be faster/easier to use the infrared serial port, its a (relatively) >trivial matter adapting most serial devices to run off that. Of course, your >OTHER problems > >Please explain how to take the following serial devices and trivially adapt >them to IrDa so I can easily use them with my Libretto: well there are a number of ways of doing things. They're (relatively) low speed so if you were willing to take them apart (and if you're lucky!) you can get the raw RX/TX lines from whatever device you're looking at BEFORE the RS-232 driver IC and pipe them through to an IrDA tranciever (I got a few Agilent HSDL-1001-011 low-speed IrDA compliant trancievers for about $4USD or so which I was going to play with, there are higher speed ones such as the HSDL-1100-018 but they're more complicated to play with due to more signal shaping components required). If you're unlucky you'll find that the signals emerge from the microprocessor already at RS-232 levels so you'll need to use the alternative idea. Both trancievers should give you at least a foot of transmit distance with a visible angle of a bit over 90º (thats being conservative, I've had better but things start going loopy). I could get one of them going at a *reasonable* speed even with my dodgy soldering but I wouldn't want to go any higher than say 14400 with the low speed version on breadboard. These ICs have on-board amps and low-pass filters and whatnot so you just shove TTL (5 volt) level signals into them for transmit and you get back TTL signals out of them for recieve (along with the appropriate caps for nice signals, the data sheet has all the details). I went for the Agilent tranciever because it had all the basic circuit diagrams already on the data sheet to get the thing going on TTL logic levels (it only needed 2 capacitors and a resistor in my situation). An alternative that I understand people have used successfully is the Vishay-Telefunken TFDS4500 unit but I don't know how good or otherwise that is because I can't get it here. I'll be mucking around with the Agilent tranciever hooked up to a PIC16F84 microcontroller some time soon, I'll make mention of what sort of success I get with that (thats if I get around to it!). The alternative is to use a second RS-232 driver and voltage pump IC such as one of the Maxim MAX232 devices, plug the RS-232 level signals from your device into the RS-232 line level side of the MAX232 then back the TTL level side of one of them onto an IrDA tranciever (again with the necessary caps and whatnot, again data sheet has all the details and if you keep the speeds to not much higher than 14400bps you can afford to breadboard the lot without worrying too much about stray capacitance ... if you want to go higher you'd want to do things properly). If you did this you could probably in fact build it into a little box - a DB9 on one end and an IrDA window on the other (plus 5V power supply of course). That'll let you make any device you've got wireless (although you've still got the cable there). Of course, all this is 'hack together' circuitry but from what I read and in my (limited!) experience it seems to work OK for low to mid range speeds (I do have some problems with my cellphone modem dropping out every now and again, I'm still wondering if thats a dry joint or a circuit design problem but its not too serious, it just means every few minutes I get a 'signal obstructed' warning from Windows but it recovers within 1 or 2 seconds so I don't actually drop the connection). *shrug* your mileage may vary. Hope this helps! - Raymond --- /~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\ | | "Does fuzzy logic tickle?" | | ___ | "My HDD has no reverse. How do I backup?" | | /__/ +-------------------------------------------| | / \ a y b o t | [EMAIL PROTECTED] | | | HTTP://www.raybot.net | | ICQ: 31756092 | Need help? Visit #Windows98 on DALNet! | \~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~/ ************************************************************** http://libretto.basiclink.com - Libretto mailing list http://libretto.basiclink.com/archive - Archives http://www.picante.com/~gtaylor/portable/faq.html - FAQ -------TO UNSUBSCRIBE------- Reply to any of the list messages. The reply mail should be addressed to: [EMAIL PROTECTED] - Then replace any text on the message's subject line: cmd:unsubscribe --------TO UNSUBSCRIBE DIGEST------ Do above but with this on subject line: cmd:unsubscribe digest **************************************************************
