`RS485-Power-Injector`

This repository contains the design files for L3X-Z's RS485 power injector which allows to directly inject battery power into the RS485 bus connecting the robot's Dynamixel MX-28AR servos.

Debug circuitry

This board contains a circuit with a RS485 driver to drive a LED to show bus activity. This circuit can also be used to interface the RS485 bus to a controller or computer. The circuit can be used with 3.3V and 5V levels. Some parts need to be changed to achieve this.

Designator	3.3V version	5V version
U1	L78L33ACUTR	L78L05ACUTR
U2	SP3485EN-L	SN75176AD

Connectors

Power Input J1

Anderson Power Pole

Pin	Signal	Description
1	+BATT	Directly to Dynamixel
2	GND

The input voltage is directly feed to the Dynamixel servo. So the maximum voltage depends solely on the servo used.

Power Input J2

Würth WR-TBL 3.5mm 2-pin screw terminal.

Pin	Signal	Description
1	+BATT	Directly to Dynamixel
2	GND

RS485 Input J3

Würth WR-TBL 3.5mm 3-pin screw terminal.

Pin	Signal	Description
1	RS485-A	Directly to Dynamixel
2	RS485-B	Directly to Dynamixel
3	GND

RS485 Input J4

JST GH 1.25mm 4-pin.

Pin	Signal	Description
1	+BATT	to Dynamixel via R2
2	RS485-A	Directly to Dynamixel
3	RS485-B	Directly to Dynamixel
4	GND

Dynamixel connectors J5 and J6

In the Dynamixel world there exist two type of connectors: Molex Mini-SPOX and JST EH.

Both are 2.5 mm pitch and use the same pin out and both can be mounted on the board. So you can decide which one to use and which fits your application and servo.

Pin	Signal	Description
1	GND
2	+BATT
3	RS485-A
4	RS485-B

RS485 Debug output J7

Pin header 2.54mm 4-pin.

Pin	Signal	Description
1	RS485_TXEN
2	RS485_TX
3	RS485_RX
4	GND

107-systems/RS485-Power-Injector