Single wire serial communication - hardware configuration

Other Hardware General Electronics
1

Hi, I have several servos that can give feedback data and I want to read. The servos use special protocol so I need to use Rx/Tx pin on my Arduino Mega to communicate with them. The problem is that a servo has only one serial communication pin so I cannot use the usual Rx/Tx wiring.

I have heard that there are some hardware configurations to properly convert UART signals to half duplex type. One is to use 2 resistors connected to Rx and Tx of Arduino and the pin of the servo. Another is to use a transistor. However, I could not find exact circuit drawings and rules to choose the values for the resistors or the transistor. Can somebody provide more information on that and explain in terms of hardware exactly how these configurations prevent the Tx writing to the Rx and the servo feedback writing to the Tx.

I am also open to other configurations that work. Still, it would be nice to know how these work as well.

2

What kind of servo are you using?

I've never heard of servos with anything serial-like for their communication; mostly they use pulses of specific lengths or something like that....

3

Dynamixel xl320

4

There's a thread about a library for that servo here:

5

Thanks, I already have a library I wrote myself that is both way communication. I will have a deeper look at the one you suggested as well. Nevertheless, it would be great if anyone explains how these hardware configurations work.