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Joined: 31/12/2012
Location: New ZealandPosts: 10039
| Posted: 10:09pm 01 Jun 2017 |
Hey there.
There is a 10k external pullup on the receiver board. This is separate from the receiver itself. This pulls up the data line to 5v at any time that the receiver module is NOT pulling the line down, so it stays idle high via the 10k resistor, even if the receiver is outputting 0v, if you see what I mean. This is simply to prevent the line floating and being susceptible to rouge data, I expect - just about any receiver you look at, has some form of pullup on the RXD line.
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