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open" baudmodes SEROUT command SOUND PAL — Parallax Forums

open" baudmodes SEROUT command SOUND PAL

Chuck ThomasChuck Thomas Posts: 39
edited 2007-12-21 17:58 in BASIC Stamp
For "open" baudmodes used in networking, add 32768 ($8000) to the values from the table above.

What is an "open" Baudmode, when used in networking?

Thank you,
Chuck

Comments

  • allanlane5allanlane5 Posts: 3,815
    edited 2007-12-20 21:23
    The "non-open" baud modes drive the signal high and low. The "open" baud modes only drive the signal one way -- they let it 'float' to the other state. This means you usually need a 10 KOhm pull-up resistor.

    The nice part of this is that you can then tie multiple pins to the data line -- one expected to transmit, while the others 'listen'. The 'open' baudmode means even if you accidentally get two 'transmitting' pins, they won't kill each other -- the data will be garbled, but you can recover from that. Tieing two driver pins to each other, then commanding one to output a "HIGH" while the other outputs a "LOW" will destroy one of the output drivers with a short-circuit.

    The open baud modes avoid this scenario.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2007-12-20 23:36
    For the SoundPAL, the open baudmode facilitates two-way communication on a single pin, without having to worry about bus conflicts. The required pull-up is built in.

    -Phil
  • Chuck ThomasChuck Thomas Posts: 39
    edited 2007-12-21 17:58
    Thank you allanlane5·and Phil.
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