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activity LED for serial IO and/or I2C — Parallax Forums

activity LED for serial IO and/or I2C

ZootZoot Posts: 2,227
edited 2006-04-26 18:02 in BASIC Stamp
I've got 2 mounted LEDs on the front of my project that won't get hooked up to pins. Could I hook one LED up to my serial I/O line and one to my I2C SDA or SCL line? Would I get any adverse effects on my data I/O? I was thinking of behavior along the lines of the green "act" LEDs on the PSC and the Ping, or like the disk access light on a desktop computer.

There is a circuit kind of like this in Robotics with the Boe-bot, p.48., for monitoring servo signal pulses. I was thinking a bigger resistor (1k) for a dim LED.

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When the going gets weird, the weird turn pro. -- HST

Comments

  • PJAllenPJAllen Banned Posts: 5,065
    edited 2006-04-26 16:53
    I think that the pulses will be so quick that you can/could not see them.
  • ZootZoot Posts: 2,227
    edited 2006-04-26 17:03
    The I2C I'm not sure about, yeah. But I found the schematic of the LED act light for the PSC (attached below). I run my PSC at 38k and I see that light all the time....

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    When the going gets weird, the weird turn pro. -- HST
    serLED.jpg
    332 x 318 - 28K
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2006-04-26 18:02
    Not to say there aren't options.· You could use an op-amp, they have high ZIN, and use that to trigger a 555 (as a one-shot) which you could use as a·"pulse-stretcher."· This would indicate "activity".
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