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ATMEGA versus FT232R — Parallax Forums

ATMEGA versus FT232R

RaymanRayman Posts: 14,844
edited 2012-02-28 14:59 in Propeller 1
I've been happy with the FT232R as a USB to serial bridge to program the Prop.

But, I just noticed an ad for the Arduino Uno where they say the big improvement was to replace the FT232R with an ATMEGA832.
The price looks comparible... The software looks free... The size may be a bit bigger...

But, I'm not very familiar with ATMEGA stuff, anybody know if it makes sense to use ATMEGA832 instead of FT232R?

Comments

  • LeonLeon Posts: 7,620
    edited 2012-02-28 03:13
    I don't think that that there are any Windows drivers for it.
  • RaymanRayman Posts: 14,844
    edited 2012-02-28 06:13
    Appears that Sparkfun figured it out... Looks like they just edited some .ini file and make is show up as a "Sparkfun serial port"...
  • RDL2004RDL2004 Posts: 2,554
    edited 2012-02-28 06:50
    I bought one of those Uno R3 boards about a week or so ago, best I remember it used an .inf file to install. The install failed because the (Windows XP) computer was missing a driver file, usbser.sys which is supposed to be part of SP3. For some reason this computer was missing the usbser.sys file, even though Service Pack 3 had been installed. I had to find the SP3 disk, search through the .cab files and manually install the usbser.sys driver. Took about an hour. That and the stupid USB type B jack on the board kind of soured me on the whole thing and I haven't messed with it since (I have about 20 type A mini cables, but the only type B that I have is plugged into my printer). I'll have to check in to what Sparkfun did.
  • GordonMcCombGordonMcComb Posts: 3,366
    edited 2012-02-28 09:01
    I'm not sure what SparkFun has to do with it, as the appropriate INF files for the Uno come with the latest builds of the IDE from arduino.cc. The Uno boards with the Atmel Mega8 chip for USB now use the generic usbser.sys driver that comes with Windows.

    That said, if given the choice I bet most users would opt for the FTDI chips and the fewer bugs that come with them. The "promise" of the Atmel chips is that they're reprogrammable and technically capable of acting as either USB host or slave, though at least on the Arduino there aren't too many examples of altering the Uno to be a host. Secondarily, for Mac users there are no drivers to install for the Uno.

    -- Gordon
  • CircuitsoftCircuitsoft Posts: 1,166
    edited 2012-02-28 09:03
    Usually, the ATMega8u2, or some-such, is programmed as a CDC-ACM device, which appears as a modem and gets a COM port number, but you can't set baud rate on it since it's assumed that the USB device itself is the end that you're talking to.
  • CircuitsoftCircuitsoft Posts: 1,166
    edited 2012-02-28 09:04
    Not necessarily a host, but a different type of a device, such as USB-HID, or even MSC.
  • jmgjmg Posts: 15,183
    edited 2012-02-28 14:22
    Rayman wrote: »
    I've been happy with the FT232R as a USB to serial bridge to program the Prop.

    But, I just noticed an ad for the Arduino Uno where they say the big improvement was to replace the FT232R with an ATMEGA832.
    The price looks comparible... The software looks free... The size may be a bit bigger...

    But, I'm not very familiar with ATMEGA stuff, anybody know if it makes sense to use ATMEGA832 instead of FT232R?

    That would be the USB AVR, the ATmega8u/ATmega16u.
    I think I also read that the Mega8u was 'outgrown' for some apps, and they moved to Mega16u.

    There are also Silabs, Microchip and others small uC with USB, that are good price points.

    Yes, these will gradually move to replace FT232R's and the like.

    I like the idea of a 'smarter' USB block, that is part instrument to assist in development.

    I'm getting some samples of this one
    http://www.megawin.com.tw/megawin_EN/ProductShow.asp?ID=206

    It claims to have a 2.5K DFU USB boot loader preinstalled, so you can easily update your firmware.

    and if you want really new on this topic, with a controlled regulator, and power drive as well, and no Xtal, see my other thread

    http://forums.parallax.com/showthread.php?138281-USB-ADC-Controlled-Vcc-in-6x6mm-package
    Not quite as cheap as Mega8u, but it includes a user adjustable regulator.
  • jazzedjazzed Posts: 11,803
    edited 2012-02-28 14:31
    I've looked at using the AVR for serial port as well. It would save some money and real-estate.
    I always thought it would make an odd Propeller board accessory though.
  • Dr_AculaDr_Acula Posts: 5,484
    edited 2012-02-28 14:37
    Could this be a solution for faster downloads for those big C programs etc?

    Having installed a few devices over the years, I'd be interested to see how these install, what they appear as in the Device Manager, and how you interface to them from various programs you might write in C/Basic/other language on the PC.

    Any idea about cost?
  • LeonLeon Posts: 7,620
    edited 2012-02-28 14:51
    http://www.findchips.com/avail?part=ATMEGA8U2-MU
  • jmgjmg Posts: 15,183
    edited 2012-02-28 14:59
    Dr_Acula wrote: »
    Could this be a solution for faster downloads for those big C programs etc?

    Having installed a few devices over the years, I'd be interested to see how these install, what they appear as in the Device Manager, and how you interface to them from various programs you might write in C/Basic/other language on the PC.

    Any idea about cost?

    The easiest install is always to use a Serial-clone, and I'm sure the handshake lines that Serial supports, can be used to 'steer' a PC flow.

    So you can download to CodeEE, and run a Debug-terminal, and communicate with an 'instrument set' inside the USB.uC
    (ie that's three destinations, but you tend to not need all 3 live at once )

    For absolute raw speed, you would need FT2232H, running high speed USB (480MBd) which can stream UART at 12MBd and above for others.

    It may be a little under that is OK, in which case the SiM3U1xx will probably support the highest Practical Full Speed USB link, as it has the highest and most flexible CLOCK generation. (so you would get close to the nice Fractional Baud in the FT2232H )
    From memory the SiM3U1xx has a M(12bit)/N(12bit) PLL scheme, which is pretty flexible.

    Price is above a Megau8U, but I'd pay +$2-3 more for finer, faster control, and better instruments.
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