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 Posted: Feb 09, 2008 - 10:33 PM |
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Joined: Nov 17, 2004
Posts: 4578
Location: Great Smokey Mountains.
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Today is my 'versus' day.
In the midst of my writing the 'Virtual Serial Port Cookbook' which uses the FTDI FT232R, Atmel introduced the AT90USB line of products. After saying shit about a thousand times I decided to soldier on with the FT232R mostly due to inertia and to a lesser extent due to the paucity of AT90USB products at the time.
Now that they have the AT90USB82 for $2,17 each per hundred at DigiKey, I'm forced to reconsider. Why the f*ck would I continue using the FTDI part which costs $3.89 each per hundred?
Well, for one thing, I know how to use the FT232R as a virtual serial port. And for another I can use it with any AVR part. BUT! why can't I use the AT90USB82 as a USB to Serial Converter for other AVR parts AND for simple applications, just use it as a combo USB/AVR and not need an extra AVR?
I noticed that Dean Camera took quite some time to understand the AT90USB parts and port the Atmel provided code to his MyUSB software - and this scared me a bit since if it caused Dean to stumble, then it isn't ready for the rest of the world. But now that Dean has got it all figured out, what would be the reason for not substituting a AT90SUB82 for an FT232R in a Virtual Serial Port application?
I'm hoping someone can come up with a compelling reason to stick with the FT232R since I really don't want to waste more brain cells learning yet another device.
Smiley |
_________________
FREE TUTORIAL: 'Quick Start Guide for Using the WinAVR C Compiler with ATMEL's AVR Butterfly' AVAILABLE AT: http://www.smileymicros.com
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Posted: Feb 09, 2008 - 11:18 PM |
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Joined: Jan 03, 2006
Posts: 3220
Location: Hemel Hemsptead, UK
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Two separate chapters, perhaps? My thought is that the FTDI is a known and proven brain-dead solution; once the drivers are on the PC the only real limitations are (a) minimum serial speed of 300 baud and (b) the small size of the package. It's an obvious solution to convert *any* existing serial AVR app and is a drop-in replacement for the MAX232 or equivalent.
The AVR USB approach, though, offers a lot more functionality in that (if I understood Dean's work) it can be set to work as any of the standard interfaces as well as just a serial link - but it's a lot more work.
Just my two cents... |
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Neil Barnes
www.nailed-barnacle.co.uk
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Posted: Feb 10, 2008 - 12:00 AM |
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Joined: Nov 17, 2004
Posts: 4578
Location: Great Smokey Mountains.
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But isn't there a 'standard' Virtual Serial Port for the AT90USB and shouldn't be as easy to use as the FTDI VCP?
Smiley
p.s. correct on the chapters comment. |
_________________
FREE TUTORIAL: 'Quick Start Guide for Using the WinAVR C Compiler with ATMEL's AVR Butterfly' AVAILABLE AT: http://www.smileymicros.com
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Posted: Feb 10, 2008 - 12:09 AM |
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Joined: Sep 21, 2005
Posts: 2111
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Option 1- spend $.50 on a max232, let the 'user' worry about buying a usb-232 adapter
Option 2- use a ft232, write a book, become rich and famous
Option 3- use at90usb, go insane trying to deal with usb, lose all fame and fortune acquired in #2
Option 4- wait for Atmel to sell a 'preloaded' at90usb with no thought required to make it work (and available in a DIP version)
Option 5- wait for Option 6
(I'm still on option 1, waiting for option 5) |
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Posted: Feb 10, 2008 - 12:36 AM |
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Joined: Jan 20, 2008
Posts: 210
Location: Canada
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Personally, USB devices that use a virtual COM port almost seem a little unprofessional to me. (The wording of that statement is probably stronger than I intend it, but I can't think of a better way to say it at the moment.)
I have probably half a dozen devices I use off and on that take this approach. I find it annoying how each one gets a COM port assigned to it and I have to remember which COM port is for which device. I would usually rather have the device with an RS232 port instead.
Of course, the average user probably is not already using a dozen actual RS232 devices and may not have RS232 ports on their computer or USB to RS232 adapters and may prefer the virtual COM port approach. |
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Posted: Feb 10, 2008 - 12:59 AM |
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Joined: Dec 11, 2007
Posts: 3139
Location: Cleveland, OH
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For me FTDI is an easy solution. If I have a project I just want to get done and move on, I can drop in an FTDI and focus on the main part of the project. Likewise, since I still program the PC side in VB, interfacing to a serial port is easy. (Enumerating them has not proven to be so easy...)
At this point for me to switch to USB within the uP would take a significant amount of time on the bench, learning the basics, without a logic analyzer or USB probe to play with. Certainly worthwhile for commercial products, but not so for my own projects, or one-off prototypes.
Likewise, writing drivers for Windows, esp a USB driver, would be a significant undertaking for me.
I'm sure it will bubble up my priority list to the top at some point, but its not there yet!
JC |
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Posted: Feb 10, 2008 - 01:01 AM |
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Joined: Nov 01, 2005
Posts: 4907
Location: Hilversum - the Netherlands
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Kevin, I use several devices with FT232R's. But the trick is to give each a unique ID, to prevent the confusion you mention. FTDI has some fine tools for that, and Smiley knows those.
Curt mentions some options, and if it's indeed a crime to get the Atmel-USB-thingies to work, I'd stick for the time being with FT232's.
Nard |
_________________
Problems with Parallel Port Programmers ? Read this:
http://www.aplomb.nl/TechStuff/PPPD/PPPD%20English.html
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Posted: Feb 10, 2008 - 01:17 AM |
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Joined: Nov 28, 2007
Posts: 62
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I'm a beginner with both AVR and FTDI, but I'm doing "experiments" with a FTDI232RL and you can use it not only with the VCP driver but also with a "FTDxx2" driver that lets you send data directly through USB, if you consider "old-style" using the virtual serial port.
Regards,
Roberto |
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Posted: Feb 10, 2008 - 01:27 AM |
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Joined: May 30, 2004
Posts: 7801
Location: Cincinnati, Ohio
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kevin123 wrote:
Personally, USB devices that use a virtual COM port almost seem a little unprofessional to me.
So, lets see...
My Dell desk-top only has one RS-232 serial port and 6 USB ports. Without an RS232 switch box, I'm left to crawling under the desk each time I use a different device on the bench. Been there, done that.
At any given time, I have the Dragon (USB), one or two ATAVRISP-MK2 programmers (USB), a Parallax USB scope, one or two project boards (usually USB), the TekTronix TDS2012 Oscilloscope (USB --> RS232 converter), the B&K programmable power supply (USB --> RS232 converter), an external USB hard drive, the ImageCraft USB security dongle, a USB memory stick, a USB Compact Flash card reader, STK500 (USB --> RS232 converter), and a 7 port USB hub handling the overflow for the PC. I can't remember what else.
I personally think USB is the way to go. I don't mind the virtual COMM port concept. If it weren't for USB, half of the equipment on my bench would either be on a shelf or require another computer/switch.
Virtual COMM ports also allow for changing the Windows assigned COMM port. This is great, in my opinion. I can move things around to where they best serve my needs - without having to change physical connections.
The external USB hub offers a measure of electrical isolation, protecting my desk-top PC from the inevitable, and disastrous brain fart.
As far as installing the drivers... Don't we have to install drivers and software for most hardware we buy - save the HMI/HID devices?
Virtual COMM drivers, just aren't a big deal - and damn convenient! |
_________________
Carl W. Livingston, KC5OTL
microcarl@roadrunner.com
It's a fundamental law of nature... All things gravitate toward total chaos!!!
The original Dragon Slayer !
Long live the AVR!!!
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Posted: Feb 10, 2008 - 01:51 AM |
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Joined: Jan 20, 2008
Posts: 210
Location: Canada
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Quote:
If it weren't for USB, half of the equipment on my bench would either be on a shelf or require another computer/switch.
If half of my equipment was on my bench, I would need a bigger bench.  |
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Posted: Feb 10, 2008 - 01:55 AM |
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Joined: Jan 20, 2008
Posts: 210
Location: Canada
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Quote:
Virtual COMM drivers, just aren't a big deal - and damn convenient!
I don't think they are a BIG deal either. I just prefer more pure USB devices. Once the driver is installed, I find a pure USB device more convenient than a virtual COM driver.
No big deal either way... |
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Posted: Feb 10, 2008 - 02:01 AM |
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Joined: Dec 11, 2007
Posts: 3139
Location: Cleveland, OH
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Is the question what do you want from a commercial product you buy today, ext HD, test equip, PDA interface, etc.; or what are you designing into your own projects, that you build on your bench?
JC |
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Posted: Feb 10, 2008 - 02:09 AM |
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Joined: May 30, 2004
Posts: 7801
Location: Cincinnati, Ohio
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DocJC wrote:
Is the question what do you want from a commercial product you buy today, ext HD, test equip, PDA interface, etc.; or what are you designing into your own projects, that you build on your bench?
JC
Theoretically, wouldn't they all eventually end up the same? At least to someone else.
I mean, what I build and use on my bench today, might end up connected to your computer tomorrow - be it a piece of test equipment, or a consumer device.
EDIT:
Hey DocJC... How's the weather up in Cleveland?
And why is your avatar bearing the mark of the Red 'X'? |
_________________
Carl W. Livingston, KC5OTL
microcarl@roadrunner.com
It's a fundamental law of nature... All things gravitate toward total chaos!!!
The original Dragon Slayer !
Long live the AVR!!!
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Posted: Feb 10, 2008 - 03:37 AM |
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Joined: Dec 11, 2007
Posts: 3139
Location: Cleveland, OH
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Hi Carl,
If all of my projects, (actually even a few), ended up on everyone's kitchen counter, or work bench, my bio would say Hawaii, not Cleveland! 
I was thinking in terms of the hobbiest / Ham, etc, projects, more than the commercial ones. I expect commerical products to have true USB interfaces, and user friendly drivers these days. I'm just not there yet, on my bench. 
Wx in Cleveland is gray skys and cold. If you ask again in August I'll reply: Wx in Cleveland is gray skys and hot. You are familar, no doubt, with the old saying about the only certainties in life being: 1) Death, 2) Taxes, and 3) Gray skys in Cleveland 
I spent an evening shrinking several gifs, carefully making each one 60 x 60 pixels, and makng a nice animated gif, to upload, (Not to be outdone by some other animated avatars...), but I can not get it to load / work. I tried the upload via browse, and I posted it on my web site and tried uploading from there, no luck.
I searched the forum and saw a few similar comments, figured I'd upload again next week, see if the problem was fixed.
Either that or try uploading a "Real Picture", illustrating my gray and perpetually thinning hair! 
JC |
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Posted: Feb 10, 2008 - 04:08 AM |
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Joined: Mar 28, 2001
Posts: 13030
Location: Sydney, Australia (Gum trees, Koalas and Kangaroos, No Edelweiss)
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When Atmel provides the same functionality to their chips as FTDI does, then I'll think about using Atmel chips.
Whilst I'm still waiting for a sample Atmel USB chip (about 2 years now) I have used a few FTDI chips, WHITHOUT EFFORT. As mentioned in another thread, I needed some quick MP3 playback from a USB memory stick to demostrate a possible new product to a client I designed a small PCB for.
Using a VMUSIC module and a simple firmware mod to the client's Tiny2313 firmware, I demonstrated another way they could implement the functionality of their product.
Now let's see...I think we MAY be at the stage that we are able to open a file with an Atmel USB chip...is that correct? |
_________________
John Samperi
Ampertronics Pty. Ltd.
www.ampertronics.com.au
* Electronic Design * Custom Products * Contract Assembly
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Posted: Feb 10, 2008 - 04:15 AM |
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Joined: May 30, 2004
Posts: 7801
Location: Cincinnati, Ohio
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js wrote:
Now let's see...I think we MAY be at the stage that we are able to open a file with an Atmel USB chip...is that correct?
Possibly! But only if you plan on donating what little hair you appear to have left to Dean (abcminiuser) to replace all of the hair he lost while getting his USB project up and running. |
_________________
Carl W. Livingston, KC5OTL
microcarl@roadrunner.com
It's a fundamental law of nature... All things gravitate toward total chaos!!!
The original Dragon Slayer !
Long live the AVR!!!
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Posted: Feb 10, 2008 - 04:22 AM |
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Joined: Mar 28, 2001
Posts: 13030
Location: Sydney, Australia (Gum trees, Koalas and Kangaroos, No Edelweiss)
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Quote:
only if you plan on donating what little hair you appear to have left to Dean
He doesn't need it yet! But it should not be THAT hard. We should be given working firmware for these beasts for a few common applications (may be they do already??).
I surely don't want to do a USB driver for one. Why...I would have to use C...bad thing. |
_________________
John Samperi
Ampertronics Pty. Ltd.
www.ampertronics.com.au
* Electronic Design * Custom Products * Contract Assembly
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Posted: Feb 10, 2008 - 07:34 AM |
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Joined: Jan 23, 2004
Posts: 7014
Location: Melbourne, Victoria, Australia
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I admit, getting my head around it all was a little difficult when I first started, but I believe I'm pretty much fine now - I can explain just about any aspect of USB sans the physical signaling layer.
Now that MyUSB works, the hair-loss should be restricted to yours truly only. Projects based on MyUSB (like the demos included with the library) are actually quite small in LOC, as well as simple to understand. A fully functioning mouse using the USBKEY's joystick requires only about 100 lines! I'm sold on the AT90USBXXX devices, and they are very versatile, and easy to use when you have a framework library to build your applications on top of.
Quote:
Now let's see...I think we MAY be at the stage that we are able to open a file with an Atmel USB chip...is that correct?
The Mass Storage MyUSB demo can enumerate to a host computer as a removable disk. The MyUSB Mass Storage Host demo can enumerate a disk, and read/write blocks. Chuck one of the open source free FAT libraries on top of the latter and you can modify the disk contents to your heart's content.
- Dean  |
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Posted: Feb 10, 2008 - 07:43 AM |
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Joined: Mar 28, 2001
Posts: 13030
Location: Sydney, Australia (Gum trees, Koalas and Kangaroos, No Edelweiss)
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Quote:
I'm pretty much fine now
Do you have a doctor's certificate?  |
_________________
John Samperi
Ampertronics Pty. Ltd.
www.ampertronics.com.au
* Electronic Design * Custom Products * Contract Assembly
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Posted: Feb 10, 2008 - 08:14 AM |
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Joined: Apr 12, 2005
Posts: 278
Location: Jõhvi, Estonia
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| The reality is that RS232C never dies. |
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