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Hydra Schematic? — Parallax Forums

Hydra Schematic?

Oldbitcollector (Jeff)Oldbitcollector (Jeff) Posts: 8,091
edited 2007-03-22 14:43 in Propeller 1
I don't suppose we could have access to the schematic for the Hydra?

Oldbit

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2007-03-20 04:36
    The schematic is in several pieces in appropriate chapters of the book (pretty much one I/O block at a time). There's not much else that is different from any other Propeller board. Is there something specific you're interested in?
  • Oldbitcollector (Jeff)Oldbitcollector (Jeff) Posts: 8,091
    edited 2007-03-20 04:57
    I'm interested into the card interface in the center. Also, it appears there is at least one other chip on the Hydra. (Can't quite tell from the pictures)

    Really, I'm just looking for more ideas for stuff to add to my Propeller micro. tongue.gif
    I'm working on my first .spin object (An Atari joystick interface on pins 4-8), and was thinking that with everything on my board already, it appears I'm approaching the functionality of the Hydra itself.

    Oldbit
  • Mike GreenMike Green Posts: 23,101
    edited 2007-03-20 20:09
    The card interface description is downloadable from the main Hydra store page: www.parallax.com/detail.asp?product_id=32360.

    The other chips include an EEPROM, the USB-serial adapter, and the buffer for the expansion card.
  • Spork FrogSpork Frog Posts: 212
    edited 2007-03-20 21:26
    Well, it's really a buffer for the VGA port.
  • Mike GreenMike Green Posts: 23,101
    edited 2007-03-20 22:48
    Sorry, you're right.
  • mahjonggmahjongg Posts: 141
    edited 2007-03-22 14:43
    One difference between the hydra and most other designs is the way the PS/2 mouse and keyboard interfaces operate.

    Most systems use a single I/O port for each clock and data line and ignore the 3,3Volt level to 5Volt level translation problem (the P/S mouse and keyboard are 5 Volt devices, but are controlled with 3,3Volt levels).

    The Hydra however uses two I/O ports and a transistor circuit to do level translation, one port acts as an input, and another one as an output to the level translating transistor.

    This means that "any" mouse or keyboard will work, while on the other systems in theory some mouses or keyboards might not work.

    The downside is that the mouse keyboard drivers of the hydra are different from the other ones, and that the PS/2 ports of the hydra need eight I/O ports instead of just four.


    Mahjongg
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