[aprssig] has anyone built/modified a USB to TTL level converter??

[Dave]

You can't do that, you'll end up with the radio and the converter 
fighting over who has the bus (Bus Contention) unless you use at least 
one non inverting open collector (open drain) buffer between the USB/TTL 
chip TX pin, and the CI-V bus.

Dave G0WBX


On 3 Jun 2011 at 6:49, alexandru wrote:

> 
>     Bob,
> 
>     all you have to do, is to put together RXD & TXD pins from CP 2101
>     output module and you haveCI/V for your Icom (rxd+txd and ground
>     of course) the same think i made it for my IC7000 and work nice at
>     4800 bauds without max, without cell , etc...
> 
>     good luck and 73!
> 
>     aslexander - yo2ldk
> 
> 
>     From: Bob <k8ys at fuse.net>
>     To: TAPR APRS Mailing List <aprssig at tapr.org>
>     Sent: Fri, June 3, 2011 1:19:46 PM
>     Subject: Re: [aprssig] has anyone built/modified a USB to TTL
>     level converter??
> 
>     well, yeah,
> 
>     I have an IC706 that it TTL.
>     I have a MAX233 IC (TTL to RS232 level 
>     converter/interface/transceiver)
>     I have a Sil Labs CP2101 already mounted on a small board 
>     with a USB cable,
>     and I have the drivers for the CP2101. This used to be a 
>     "goezinta box" for
>     a cell phone. 
> 
>     My goal was to build, kluge together an CI/V that went from 
>     USB to TTL by
>     raiding my junque box.
> 
>     I have TTL to RS232 level converters that I have built in 
>     the past, but I
>     have never played with USB and since all of my computers 
>     these days are USB
>     and none with a real (semi real) RS232 interface, I brought 
>     my question to
>     this group.
> 
>     Bob
> 
>     -----Original Message-----
>     From: aprssig-bounces at tapr.org [mailto:aprssig-
>     bounces at tapr.org] On Behalf
>     Of Greg D
>     Sent: Friday, June 03, 2011 2:44 AM
>     To: TAPR APRS Mailing List
>     Subject: Re: [aprssig] has anyone built/modified a USB to 
>     TTL level
>     converter??
> 
>     Hi Bob,
> 
>     Uh, let me see if I have this right...
> 
>     You are trying to drive your IC706 rig from a computer. The 
>     computer has 
>     a regular (RS-232) serial port (or you can make one with a 
>     standard 
>     dongle), and the radio needs TTL. You want to connect the 
>     two, right?
> 
>     A TTL "high" signal (+3v or so) translates to a negative 
>     half dozen 
>     volts or so on RS-232, and a TTL "low" (0v) maps to a 
>     positive half 
>     dozen volts or so on RS-232. You don't need to make this any more
>     complicated than it is.
> 
>     If you're halfway handy with a soldering iron, to drive the 
>     rig from the 
>     computer, all you need is a transistor, diode, and a 
>     resistor or two. 
>     Let me know if you are interested and I can dig up the 
>     schematic. I 
>     drive my Yaesu FT-736R like this, and it works great.
> 
>     To drive the computer from the rig, it's something equally 
>     simple. The 
>     Yaesu rig doesn't talk back to the computer (really 
>     annoying!), but I 
>     think the diagram I'm remembering has both directions 
>     covered. If you 
>     can find the schematic for the original FODTrack satellite 
>     tracking 
>     controller, I believe it's in there.
> 
>     Greg KO6TH
> 
> 
>     Bob wrote:
>     > I need TTL.
>     > I have RS232
>     > I have USB
>     > I do not have a RS232 port. Rules out the standard USB to 
>     RS232 dongle.
>     >
>     > I think that I want to take an old cell phone to computer 
>     interface that
>     has
>     > a USB to RS232 level converter. It is a common chip, and I have
>     the drivers. > > I want to take the RS232 from the cell phone
>     cable and feed it to a MAX233 > to get TTL in/out. > > Then use
>     the TTL to talk to the IC706m2g to control the radio. > > Without
>     reinventing the wheel, is there a "better way"? > > Bob K8YS > > >
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> 
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