USB to RS232 one chip solution

[mkr5000]

I've seen some parts FT232* and the like but not familiar with them.

What is the current state of the art chip solution for rs232 to usb
conversion?

I just have some simple 8 bit no parity 1200 baud I'd like to get into
USB.

Will I have to write any software for the chip or can I simply set the
chip by some pin manipulation?

Something simple/cheap/popular.

Thanks kindly for any help.

 

[ScadaEng]

I've seen some parts FT232* and the like but not familiar with them.

What is the current state of the art chip solution for rs232 to usb
conversion?

I just have some simple 8 bit no parity 1200 baud I'd like to get into
USB.

Will I have to write any software for the chip or can I simply set the
chip by some pin manipulation?

Something simple/cheap/popular.

Thanks kindly for any help.

http://www.saelig.com/miva/merchant.mvc?Screen=PROD&Product_Code=U012&Category_Code=U

Saelig has this one, you set your pc for a virtual comm port through
software they provide.
You write your apps as if you were writing to a standard RS232 comm port! No
messing with
USB drivers.

 

[JW]

I've seen some parts FT232* and the like but not familiar with them.

What is the current state of the art chip solution for rs232 to usb
conversion?

I just have some simple 8 bit no parity 1200 baud I'd like to get into
USB.

Will I have to write any software for the chip or can I simply set the
chip by some pin manipulation?

Something simple/cheap/popular.

Thanks kindly for any help.

Have a look at
http://www.silabs.com/tgwWebApp/pub...lers/Interface/en/interface_documentation.htm

Drivers are downloadable for Windows, Mac and Linux. You "set" the chip
(baud rate, parity, etc) using standard O/S based methods.

 

[Paul E. Schoen]

I've seen some parts FT232* and the like but not familiar with them.

What is the current state of the art chip solution for rs232 to usb
conversion?

I just have some simple 8 bit no parity 1200 baud I'd like to get into
USB.

Will I have to write any software for the chip or can I simply set the
chip by some pin manipulation?

Something simple/cheap/popular.

Thanks kindly for any help.

The Silabs CP2103 works well, and they have a demo board for about $30, but
the part is in a fine pitch DFN-28. There is also a TI TUSB3410 and a
TUSB5052 that has two UARTs and a 5 port hub.

You might also look at the Microchip PIC18F2450 and similar parts. They
have a full speed demo board (PICDEM FS USB) with a lot of free software
for about $40, and I have made a USB-Serial converter with that as well.
You don't have to do anything with the firmware, but it's good to have
access to the source so you can tweak it if you need to. And it's useful to
see what's going on "under the hood".

For any of these, you will also need something like a MAX232 to get RS232
voltages. The ICs are in the $5-$10 range in single quantities.

Paul

 

[mkr5000]

I need an education on these parts.

I have an RS485 to RS232 transceiver that I use, the TI SN75176.

I simply want to update the serial port to USB.

Looking at that CP2102, it looks like I can simply supply the SN75176
RS232 to the UART.

So, when I build my interface boxes I then program the chip's eeprom
via the USB port and my PC?

Just install their software and it sets the baud rate and all the
other parameters? Then it's a done deal?

The drivers are just for programming -- not needed after the chip is
burnt?

Thanks.

 

[Mike Harrison]

I've seen some parts FT232* and the like but not familiar with them.

What is the current state of the art chip solution for rs232 to usb
conversion?

I just have some simple 8 bit no parity 1200 baud I'd like to get into
USB.

Will I have to write any software for the chip or can I simply set the
chip by some pin manipulation?

Something simple/cheap/popular.

Thanks kindly for any help.

FTDI FT232R.
Available as chip, module and even chip-in-a-cable versions (TTL232R) .
Can produce a TXEN signal for driver enable in RS485 apps.
Good driver support for various OSs.
You can use their virtual COM port (VCP) driver to make it look like a COM port, or their D2xx
drivers which have some advantages, like not having to figure out what COM port got assigned to it,
higher baudrates and better control over timing.

You can configure a number of things using their MPROG utility, like options for the extra IO lines,
as well as programming custom product/vendor IDs so you can customise their drivers to make it look
to the user like a 'proper' dedicated USB device and not a COM port.
This is all easy to do - just look at the help for the MPROG utility at ftdichip.com

 

[mkr5000]

Ok thanks guys.

This will be fun to play with.

I'm "attempting" to write a simple application using visual basic, so
when I'm finished, I'll have to include the
driver.

You would think that if you a properly operating USB device, that
Windows would automatically recognize it and get it up and running?

Guess not.

Why is that exactly? What is in the driver that Windows XP would
need?

(Just learning).

 

[Don McKenzie]

I've seen some parts FT232* and the like but not familiar with them.

What is the current state of the art chip solution for rs232 to usb
conversion?

I just have some simple 8 bit no parity 1200 baud I'd like to get into
USB.

Will I have to write any software for the chip or can I simply set the
chip by some pin manipulation?

Something simple/cheap/popular.

Thanks kindly for any help.

If you really need RS-232 hardware levels:
http://www.dontronics-shop.com/RS-232-Converters-p-1-c-288.html
will give you some choices. To my knowledge, it has never been done in
one IC.

However, as long as it is a micro or similar that you are supporting,
then you don't need to do the double conversion to/from hardware RS-232,
you skip it, and connect one of these direct to your micro:
http://www.dontronics-shop.com/USB-Module-Add-Ons-p-1-c-313.html

Hope this helps

Cheers Don...



--
Don McKenzie

Site Map: http://www.dontronics.com/sitemap
E-Mail Contact Page: http://www.dontronics.com/email

Intelligent 2.83" AMOLED with touch screen for micros:
http://www.dontronics-shop.com/product.php?productid=16699

 

[Don McKenzie]

If you really need RS-232 hardware levels:
http://www.dontronics-shop.com/RS-232-Converters-p-1-c-288.html
will give you some choices. To my knowledge, it has never been done in
one IC.

However, as long as it is a micro or similar that you are supporting,
then you don't need to do the double conversion to/from hardware RS-232,
you skip it, and connect one of these direct to your micro:
http://www.dontronics-shop.com/USB-Module-Add-Ons-p-1-c-313.html

sorry, that first URL was incorrect.

http://www.dontronics-shop.com/USB-Converters-p-1-c-265.html
will give you USB to RS-232, and more usb to TTL options.

Cheers Don...



--
Don McKenzie

Site Map: http://www.dontronics.com/sitemap
E-Mail Contact Page: http://www.dontronics.com/email

Intelligent 2.83" AMOLED with touch screen for micros:
http://www.dontronics-shop.com/product.php?productid=16699

 

[mkr5000]

The downside of USB I suppose is the complexity of it's approach and
hence, the inability of Windows to integrate with it in a plug and
play fashion?

It seems to me I've had some devices that were plug and play without
drivers (if I remember right) and some where there were drivers that
needed to be installed.

I wish I knew more about why that is.....must be some very specific
information required in code, I guess.

 

[[email protected]]

The downside of USB I suppose is the complexity of it's approach and
hence, the inability of Windows to integrate with it in a plug and
play fashion?

USB is considered to be 'plug and play' but pretty much all USB
devices except for
keyboards/mice and disk drives (including flash ones) will require
drivers to be
installed... in the windows world.

A lot of linux distributions come with drivers for assorted USB-serial
widgets already installed.

Actually there is a downside to the USB serial devices. Latency is
often substantially higher
than a real serial port. You can shove a lot of data through the
things, often at higher baud rates
than the old serial port speeds. But because of the packetized way
USB works, you want
to write software protocols that stream data and use block writes to
the O/S serial port
layer, because lots of little few- or one-character writes, or worse,
write and wait for read,
will slow you down due to the latency hits. For a lot of applications
this is not an issue,
the latencies are small, but if you need to move a lot of data quickly
you have to think about
keeping it flowing smoothly.

 

[mkr5000]

I follow you....exactly what I needed to know.

I guess I was just naive in thinking that along with a new standard
like USB, that there would also be more progress toward compatibility
between devices and manufacturers, etc.

Sometimes my dreaming interferes with my sense of logic.

 

[Marte Schwarz]

Hi,

I just have some simple 8 bit no parity 1200 baud I'd like to get into
USB.
Will I have to write any software for the chip or can I simply set the
chip by some pin manipulation?

Something simple/cheap/popular.

http://www.recursion.jp/avrcdc/

www.obdev.at

Good luck

Marte

 

[John Devereux]

If I were you, I would skip the COM port approach and go directly for the
d2xx driver DLL FTDI provides - it's far more flexible and in some ways
easier to deal with.


Up to a point - the power, bus and handshake is done automatically, the
rest is handled by the driver.


FTDI provide two drivers for the FT232R chip.

The first and most low level is the d2xx driver. This communicates with
the chip in a low level fashion and can control the chips features whilst
still hiding all of the
messy USB stuff.

The second driver is a virtual com port driver - it provides an interface
to your standard COM: file. This requires the d2xx driver to function.

Whilst XP knows how to send raw data to the chip, it doesn't know what
data the device is expecting nor can it possibly know what functions the
chip has and what commands the functions require. These parts are what
the driver is for.

Although there is no reason why Microsoft could not have included a
suitable driver within XP.

I was impressed that my two USB:RS232 dongles "just worked" under
linux. (An FTDI one and some Chinese noname thing - Prolific?).

 

[Keith M]

If I were you, I would skip the COM port approach and go directly for the
d2xx driver DLL FTDI provides - it's far more flexible and in some ways
easier to deal with.

I can second both the FTDI usb chip-recommendation, and the
recommendation to use the d2xx drivers.

The advantage of going the Virtual Com Port route is that you can use
standard windows com-port calls.... where you have to use FTDI's calls
with the D2XX dll. The D2XX drivers get you closer to the hardware, and
you can talk to the chip without figuring out how they mapped the
various functions into the standard microsoft serial framework.

FTDI's chips, drivers, documentation, and support are all top notch in
my book. I've had great success using them in a project of mine.

HTH

Keith

 

[TheM]

Silabs has a nice part, too, and it doesn't even need a quartz. Its also very
easy to generate the driver code with your company name etc. I found it
to be the best all-around at the time for virtual com port.

Mark

 

[Paul E. Schoen]

Silabs has a nice part, too, and it doesn't even need a quartz. Its also
very
easy to generate the driver code with your company name etc. I found it
to be the best all-around at the time for virtual com port.

The main problem with the Silabs CP2102/3 is the fine pitch DFN28 package.
It looks like it would be nearly impossible to hand solder. The TI parts
look good, and they are in leaded SMT packages that can be hand soldered.
But at this point I am going with the PIC18F2450. It gives me the most
versatility, and I learned a lot about USB when I tweaked the sample code.
Having a device available in DIP and SOIC packages is also a plus.

Paul

 

[TheM]

The main problem with the Silabs CP2102/3 is the fine pitch DFN28 package. It looks like it would be nearly impossible to hand
solder. The TI parts look good, and they are in leaded SMT packages that can be hand soldered. But at this point I am going with
the PIC18F2450. It gives me the most versatility, and I learned a lot about USB when I tweaked the sample code. Having a device
available in DIP and SOIC packages is also a plus.

Paul

Its not as bad as it looks. Hot air gun is needed, though. DFN is becoming
popular, it seems (with manufacturers), so its better to get used to it as you
may not have a choice in the future.
The problem I had with TI is that you needed EEPROM, if I remember correctly.
AFAIR something about it was a show stopper for me.

Mark

 

[Rich Webb]

Its not as bad as it looks. Hot air gun is needed, though. DFN is becoming
popular, it seems (with manufacturers), so its better to get used to it as you
may not have a choice in the future.

As it happens, Sparkfun used a CP2103 in part of their tutorials on
SMT and hot air. I haven't tried any of the "hidden pad" parts,
myself; there's a certain comfort level when you can actually *see*
the pins...

<http://www.sparkfun.com/commerce/present.php?p=SMD-HowTo-6>