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Connecting Propellers via USB 2.0 — Parallax Forums

Connecting Propellers via USB 2.0

Kirk FraserKirk Fraser Posts: 364
edited 2011-04-01 11:20 in Propeller 1
I want to connect about 10 Propellers via USB 2.0 so they can report sensor data being evaluated in a feedback loop on each Cog which responds to commands sent in from a PC. I hope this can work over wireless. Searching this forum for USB produced no hits. USB is used for programming Propellers but after programming can it be used for this type of communication?

Let's say one Cog can be used to handle the USB port. How does one address the other chips without an interrupt to tell when to send or receive? Thank you.

Comments

  • Toby SeckshundToby Seckshund Posts: 2,027
    edited 2011-04-01 01:22
    There has been a thread on USB, but it was 12Mbs (full speed) and not host mode. I think it was Micah (ScanLime).

    USB2 is 480Mbs so interface chips will have to be used, and I guess that one of the Porps would have to be designated as the Host.
  • Cluso99Cluso99 Posts: 18,069
    edited 2011-04-01 03:59
    I presume you are referring to the USB interface to the PC using the FTDI chip. This also works for communications to the pc. On the pc end we often use a terminal program such as PST (Propeller Serial Terminal) and on the prop end we use the FullDuplexSerial object - it is downloaded when you install PropTools, so there is a demo program to use it there too. Usually we use 115,200 baud which works fine. You will then need to use a program to interface props between each other. This depends on the speed in which you need to transfer data and if it is bi-directional or just one way. For instance, you could "multidrop eanch prop on the one line using a pullup resistor and wired-or (used by having the outa pins permanently low, and enablind/disabling the pin using dira).

    Hope this helps to give you a start to ask some more questions.
  • Kirk FraserKirk Fraser Posts: 364
    edited 2011-04-01 11:06
    What crystal drives the Propeller to maximum speed? I've seen a range of 4-8 MHz and a possibly not maximum internal speed of 80 MHz discussed in the Q/A (which would require at least 10 MHz).

    I note a seperate chip is required for 12 bit A/D to perform the BS2's RCTIME command. How is 12 bit PWM possible?
  • PublisonPublison Posts: 12,366
    edited 2011-04-01 11:20
    A 5Mhz crystal at PLL x16 would yield 80Mhz. A 6.25Mhz at Pll x16 would give you 100Mhz. Both crystals are available from Parallax. Higher than 100Mhz have been achieved, but with strict design considerations, (Bypass and Bulk capacitors and smart PCB layout)

    Kirk Fraser wrote: »
    What crystal drives the Propeller to maximum speed? I've seen a range of 4-8 MHz and a possibly not maximum internal speed of 80 MHz discussed in the Q/A (which would require at least 10 MHz).
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