Dr_Acula said...
Quick answer - 5V into the propeller - use a 1k resistor in series.
By my quick back of the envelope calculations (and even allowing for the clamp diodes to drop 0.6v) 5V into a 3.3V input via a 1K resistor is going to see 1.1mA (remember I assume the clamp diode is 0.6v). The clamp diodes are rated at 500uA, so you are exceeding their rating by a factor of 2. If you don't take into account the clamp diode voltage drop, then you are exceeding their rating by over 3x.
My calcs come out at ~3.3K to be safe.
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If you always do what you always did, you always get what you always got.
pusink
Posts: 68
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Yes, No, Maybe, Could you repeat the question?
Depends.
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www.smarthome.viviti.com/build
By my quick back of the envelope calculations (and even allowing for the clamp diodes to drop 0.6v) 5V into a 3.3V input via a 1K resistor is going to see 1.1mA (remember I assume the clamp diode is 0.6v). The clamp diodes are rated at 500uA, so you are exceeding their rating by a factor of 2. If you don't take into account the clamp diode voltage drop, then you are exceeding their rating by over 3x.
My calcs come out at ~3.3K to be safe.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
If you always do what you always did, you always get what you always got.
http://forums.parallax.com/showthread.php?p=857322