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Topic: Communicating with an Arduino that is relatively far away (Read 4 times) previous topic - next topic

Graynomad

RE is active low, on the right-hand chip it's pulled high.

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Rob
Rob Gray aka the GRAYnomad www.robgray.com

Nico V


RE is active low, on the right-hand chip it's pulled high.

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Rob

Aha, thanks for that hint! I thought something might be up with it, with the slash after the name or the "overscore". Learning by doing, I guess ;)
So I need to connect it to ground on the right side one then.

I found this table in the datasheet:


So on the left side, RE can be disconnected, DE to VCC.
On the right side, RE to GND, DE can be disconnected.

Like this?

retrolefty

On the remote end you really should ground pin 3, DE, to make sure it's transmit driver is forced off into tri-state mode.

Lefty

Nico V


On the remote end you really should ground pin 3, DE, to make sure it's transmit driver is forced off into tri-state mode.

Lefty

According to the table it shouldn't care but I guess better safe than sorry ;)

Version 4 then:

Graynomad

Quote
the slash after the name or the "overscore"

Also the small circle on the graphic, on chips that means an active low or inverted signal.

Just some notes about schematic layout.

If you mirror image the remote chip the drawing will be a lot clearer.

When things are tied to power rails it's almost always better (clearer) to have VCC going up and GND going down. Your caps go up.

Most beginners make a real dog's breakfast by running the GND wire to every possible place. You haven't done that which is good, in this case however I would argue that because these chips are physically remote from each other you should draw the GND line between the two to reinforce that they have to have a common GND and that that is formed by a GND wire in the cable.

______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

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