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Fastest Baud Rate using FullDuplexSerial? — Parallax Forums

Fastest Baud Rate using FullDuplexSerial?

mike56mike56 Posts: 22
edited 2009-06-18 21:00 in Propeller 1
What's the fastest baud rate I can set using the propeller to communicate with the USB FTDI chip using the fullduplexserial.spin component?

Also what's the appropriate "mode" setting (0,1,2,3)?

Thanks!

Comments

  • LeonLeon Posts: 7,620
    edited 2009-06-15 09:39
    I think I've had it running at 115k.

    Leon

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  • KyeKye Posts: 2,200
    edited 2009-06-15 13:58
    Mode 0.

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  • Mike GreenMike Green Posts: 23,101
    edited 2009-06-15 14:31
    FullDuplexSerial is supposed to run up to 230KBps with an 80MHz system clock. Personally, I'd increase the buffer sizes to 256 bytes at that speed.
  • hinvhinv Posts: 1,255
    edited 2009-06-15 15:42
    No, there is definately not a 115k limit on the FTDI driver.
    Hanno has it running at 2Mbit/sec, but he is not using FullDuplexSerial.
  • LeonLeon Posts: 7,620
    edited 2009-06-15 15:45
    I just realised that and deleted my post. They actually go up to 3 Mbaud according to FTDI.

    Leon

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  • Cluso99Cluso99 Posts: 18,069
    edited 2009-06-16 03:41
    As Mike said, you will need to increase the buffer size for higher speeds. 115,200 is used for downloading and works fine.

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  • BradCBradC Posts: 2,601
    edited 2009-06-16 05:51
    Cluso99 said...
    As Mike said, you will need to increase the buffer size for higher speeds. 115,200 is used for downloading and works fine.

    I have downloads at 230,400 and that works just peachy too. (Getting off topic though as its not using FullDuplexSerial)

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  • mike56mike56 Posts: 22
    edited 2009-06-16 09:23
    Is there a better spin object than FullDuplexSerial to get faster speeds past 115k?
  • BradCBradC Posts: 2,601
    edited 2009-06-16 10:01
    mike56 said...
    Is there a better spin object than FullDuplexSerial to get faster speeds past 115k?

    You are limited by the spin portion of the driver not the actual serial driver portion. If you want to move data around much faster than that you really need to look at moving to PASM.

    What are you actually trying to do?

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  • mike56mike56 Posts: 22
    edited 2009-06-18 19:13
    I'd like to send data to a PC for analysis as fast as possible.

    Suppose I read data from an SD card and want to stream it to the PC.· Then 115k baud is only 14.3k bytes/sec.· It would take a long time to transfer 1 megabyte from the SD card to the PC at that rate.

    Basically I want to set up a protocol where the PC and propeller can do what they do best.· I want to collect data with the prop and analyze floating point analysis in the PC in Matlab then send the result back to the prop.

    For example, if I make a 6 axis robot, it's pretty trivial to do all the inverse kinematics in matlab but a big deal to do this in a prop with no math support.

    I'd like to have the prop monitor some encoders and implement a PID loop but send the encoder values to the PC for analysis.

    Any suggestions would be appreciated.

    I think it would be very cool if there were some sort of communication program running in a cog and all it did was send the an array to over the USB bus as fast as possible.· Then users can just write there own cog programs and put it into the shared memory bus.

    ·
  • John AbshierJohn Abshier Posts: 1,116
    edited 2009-06-18 21:00
    I think ViewPort would do it (perhaps will require Ultimate version). You should ask Hanno.

    John Abshier
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