FTDI FT232BM Hyperterminal Problems

On 27 Feb, in article
     <9ec041b7.0502271200.1c055788@posting.google.com>
     cdbremer@gmail.com "C Bremer" wrote:

>paul$@pcserv.demon.co.uk (Paul Carpenter) wrote in message
> news:<20050227.1048.307069snz@pcserv.demon.co.uk>...
>> On 26 Feb, in article
>>      <9ec041b7.0502261936.72e68ed2@posting.google.com>
>>      cdbremer@gmail.com "C Bremer" wrote:
>> 
>> >"Leon Heller" <leon_heller@hotmail.com> wrote in message
>> > news:<42206ea7$0$2761$cc9e4d1f@news-text.dial.pipex.com>...
>> >> "C Bremer" <cdbremer@gmail.com> wrote in message 
>> >> news:9ec041b7.0502260348.3ad066e@posting.google.com...
>> >> > Hi.  I'm working on a project where I am connecting a Garmin OEM GPS
>> >> > Receiver (asynchronous, RX-TX-GND) through ...............
>> >
>> >> Try RealTerm (it's free). It's much better than Hyperterminal for sorting 
>> >> out comms problems.
>> >> 
>> >> Leon
>> >
>> >I downloaded Realterm and I get pretty much the same results.  COM1
>> >works fine but COM4 (USB VCP) is still garbage.
>> >
>> >On the bottom right, the indicators for 'BREAK' and 'Error' are both
>> >red for COM4 but not for COM1.  Can somebody point me to more info on
>> >what these mean or more documentation for Realterm?
>> 
>> Personally this suggests you have not interfaced to the RS232/USB
>> correctly as it looks like the signal is inverted somewhere, hence the
>> break condition.
>
>Thank you.  This was exactly the problem.  The micro (GPS) output is
>GND to 5V with the line idle output of the GPS being GND.  I inverted
>the output of the GPS with a 74LS04 (overkill, I know) and now the
>RS232/USB (FT232BM/DLP-USB232M) interface works great.

Well if you need a single inverter and you have no spare PLD/CPLD/FPGA
pins available, you could look at 74AHCT1G04GW single inverter in SOT23-5
Also called Picogate and made by Philips and TI.

I have used them for applications with a micro and NO PLD that needed a
couple of gates, so made life a whole lot easier. Even breadboarded onto
stripboard for tests.

-- 
Paul Carpenter          | paul@pcserviceselectronics.co.uk
<http://www.pcserviceselectronics.co.uk/>    PC Services
<http://www.gnuh8.org.uk/>              GNU H8 & mailing list info
<http://www.badweb.org.uk/>             For those web sites you hate

also, chekout TeraTerm !

Laurent Gauch
www.amontec.com

C Bremer wrote:
> Hi.  I'm working on a project where I am connecting a Garmin OEM GPS
> Receiver (asynchronous, RX-TX-GND) through the USB port in Windows XP.
> Initially I connected the GPS through COM1 and successfully received
> the data in HyperTerminal.  The GPS sends data at the factory default
> of 4800, 8N1.  The GPS sentence length is 55 bytes plus a LF and CR at
> the end, one sentence per second. (only the $GPGGA sentence)
> 
> Now I am trying to receive the same data via the USB port using a DLP
> Design DLP-USB232M USB Adapter.  I downloaded the Virtual Com Port
> (VCP) drivers and installed them.  The installed drivers show up in
> the device manager as "USB Serial Port (COM4)".  It is set to 4800,
> 8N1 under Properties.
> 
> When I try to connect to COM4 in HyperTerminal, I only receive
> garbage.  The data displayed in the HyperTerminal window does not
> resemble the data seen from the connection on COM1 and is not the same
> length.
> 
> I ran "Test Application V1.0" from DLP and when connected to COM1 it
> receives 113 bytes of data at a time.  When connected to COM4, 113
> bytes are also received.
> 
> The DLP board is seated in a solderless breadboard.
> 
> Does anybody know what might be going on?
> 
> C. Bremer

"Laurent Gauch" <laurent.gauch@DELETEALLCAPSamontec.com> wrote in message
news:4222E429.6040806@DELETEALLCAPSamontec.com...
> also, chekout TeraTerm !

Agreed!
Another thing against Hyperterminal: try opening a port while data comes in
from a device: HT will tell you it cannot open the port 8 out of 10 times!

Meindert

paul$@pcserv.demon.co.uk (Paul Carpenter) wrote in message news:<20050227.2142.307079snz@pcserv.demon.co.uk>...
> On 27 Feb, in article
>      <9ec041b7.0502271200.1c055788@posting.google.com>
>      cdbremer@gmail.com "C Bremer" wrote:
> 
> >paul$@pcserv.demon.co.uk (Paul Carpenter) wrote in message
> > news:<20050227.1048.307069snz@pcserv.demon.co.uk>...
> >> On 26 Feb, in article
> >>      <9ec041b7.0502261936.72e68ed2@posting.google.com>
> >>      cdbremer@gmail.com "C Bremer" wrote:
> >> 
> >> >"Leon Heller" <leon_heller@hotmail.com> wrote in message
> >> > news:<42206ea7$0$2761$cc9e4d1f@news-text.dial.pipex.com>...
> >> >> "C Bremer" <cdbremer@gmail.com> wrote in message 
> >> >> news:9ec041b7.0502260348.3ad066e@posting.google.com...
> >> >> > Hi.  I'm working on a project where I am connecting a Garmin OEM GPS
> >> >> > Receiver (asynchronous, RX-TX-GND) through ...............
> >> >
> >> >> Try RealTerm (it's free). It's much better than Hyperterminal for sorting 
> >> >> out comms problems.
> >> >> 
> >> >> Leon
> >> >
> >> >I downloaded Realterm and I get pretty much the same results.  COM1
> >> >works fine but COM4 (USB VCP) is still garbage.
> >> >
> >> >On the bottom right, the indicators for 'BREAK' and 'Error' are both
> >> >red for COM4 but not for COM1.  Can somebody point me to more info on
> >> >what these mean or more documentation for Realterm?
> >> 
> >> Personally this suggests you have not interfaced to the RS232/USB
> >> correctly as it looks like the signal is inverted somewhere, hence the
> >> break condition.
> >
> >Thank you.  This was exactly the problem.  The micro (GPS) output is
> >GND to 5V with the line idle output of the GPS being GND.  I inverted
> >the output of the GPS with a 74LS04 (overkill, I know) and now the
> >RS232/USB (FT232BM/DLP-USB232M) interface works great.
> 
> Well if you need a single inverter and you have no spare PLD/CPLD/FPGA
> pins available, you could look at 74AHCT1G04GW single inverter in SOT23-5
> Also called Picogate and made by Philips and TI.
> 
> I have used them for applications with a micro and NO PLD that needed a
> couple of gates, so made life a whole lot easier. Even breadboarded onto
> stripboard for tests.

I took out the 74LS04 and replaced it with a 2N3904 connected as a
common emitter.  Only needed 2-10k externals.

C. Bremer