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Topic: Serial in (RX) intermittent on Arduino clone (Read 7 times) previous topic - next topic

Graynomad

#5
Jan 12, 2011, 04:04 pm Last Edit: Jan 12, 2011, 04:05 pm by graynomad Reason: 1
Quote
The output pin of a 4N25 opto-isolator

That's why you need the resistor then as the opto OP is open collector, it either pulls low or is floating, so you need something to pull the line up.

It worked with a normal Arduino because there is a 1k resistor to the OP of the FTDI chip which will idle high, therefore you effectively have a pulll up resistor.

______
Rob

Rob Gray aka the GRAYnomad www.robgray.com

gonzogeek


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