interface serial rx/tx to 3.3 volt uP

General discussion of using Roboclaw motor controllers
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ChrisA
Posts: 23
Joined: Mon May 22, 2017 4:32 pm

interface serial rx/tx to 3.3 volt uP

Post by ChrisA » Mon Jun 19, 2017 7:07 pm

I want to connect the roboclaw serial pins to a 3.3 volt micro controller. I know to scale the TX pin with a voltage divider so as not to damage the uP RX pin.

Question. Is the 0 to 3.3 volt signal from the uP TX pin enough to drive the Roboclaw RX pin? or do I need to translate this up 5 volts? How does the RX pin work? Is it just a high value pull up?

I know I can simply experiment but I need to know if this use is in-spec and going to be reliable

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Basicmicro Support
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Joined: Thu Feb 26, 2015 9:45 pm

Re: interface serial rx/tx to 3.3 volt uP

Post by Basicmicro Support » Tue Jun 20, 2017 9:17 pm

Scaling the voltages is unnecessary. The Roboclaw is a 5v tolerant device but the underlying system is 3.3v already. You can directly connect the signal lines from the Roboclaw to a 3.3v microprocessor.

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