LSS-2MC Board

Last modified by Eric Nantel on 2023/05/29 07:33


Table of Contents


The Lynxmotion LSS-2MC ("Lynxmotion Smart Servo To Motor Controller") module was designed as a multi-purpose, Arduino programmable board intended to "bridge the gap" between a Lynxmotion Smart Servo (LSS) serial bus and one or two electromechanical devices operating on PWM input like brushed DC motors (used to rotate fans, pumps or wheels for example), or LEDs. The onboard motor controller chip also allows for control of one bipolar stepper motor using all four pins. Although a default program is included when shipped, it can be re-programmed using the standard Arduino IDE software to communicate with the onboard motor controller acting as a standard Arduino board.


  • Dual 1.2A H-Bridge motor driver (MP6508GR-P)
  • USB Type-C connector
  • 2x LSS connectors allow for daisy chaining
  • Input / Output A3 pin under the USB Type-C (Unpopulated / Solder pads only)
  • LED (red): Tx-Rx USB serial activity
  • LED (green): Power LED (PWR)
  • Arduino Nano bootloader installed & Arduino IDE compatible
  • Lynxmotion Smart Servo (LSS) mounting pattern
  • Same form factor as the LSS - Power Hub / LSS-2IO BoardLSS-5VR Board


  • Microcontroller: ATMega328P
  • USB-to-Serial IC: CH340E (Driver Download)
  • Logic voltage: 5V
  • Analog voltage: 5V
  • 5V maximum current: 200mA
  • Number of analog pins: 1 (A3)
  • Input voltage via LSS connector: 6V-12V
  • Maximum rated current through LSS connectors: 2A


The complete schematic can be downloaded HERE.


Using the LSS-2MC with its Lss2MC example code requires that the user understand the Protocol which is available  HERE.
The code is available on GitHub and in the AlternativeLSS library through the Arduino IDE library manager.

Internal Serial Connection

The board is effectively a "peripheral". In order to respond to LSS commands, it needs to be running appropriate code, or the default Lss2MC Arduino sample program.
Pinout is as follows: 

  • ATMega328P's Tx pin (D1) is connected to the LSS Tx line through a tri-state buffer (IC3) that can be enabled or disabled with pin D14.
  • ATMega328P's Rx pin (D0) is connected to the LSS Rx line.

Therefore data that is sent from an external UART device will be received on the LSS Rx line and the ATMega328P Rx pin. The LSS-2MC USB-to-Serial IC Tx is connected to the ATMega328P Rx (pin D0) through another tri-state buffer (IC4) that can be enabled/disabled with pin D7. The Lss2MC Arduino code inherently takes care of managing the pins D14 and D7 as follows :

  • D7 is LOWto disconnect 2MC USB-to-Serial IC Tx from ATMega328P Rx (pin D0) allowing the ATMega328P to receive data from the UART controller device as 2MC USB-to-Serial IC Tx is HIGH when 2MC is powered.
  • D14 is HIGH: when the 2MC Board is sending data on the LSS Tx line to an external UART device Rx pin. LSS Tx line is asserted to the 2MC Tx pin :

  • D14 is LOW: when the 2IO Board is not sending data on the LSS Tx line. The 2IO frees up the LSS Tx line to avoid bus congestion (when 2 devices sends data at the same time) :


Top External Pins

SQUARE-Red.pngVin: Input voltage supplied by LSS bus (6V to ~12V)
SQUARE-Black.pngGround (G): Common ground
SQUARE-Yellow.pngLSS Rx
SQUARE-Green.pngLSS Tx
SQUARE-Red.pngH-Bridge Output #1
SQUARE-Red.pngH-Bridge Output #2
SQUARE-Blue.pngH-Bridge Output #3
SQUARE-White.pngH-Bridge Output #4
Bottom Solder Pins (Optional)

SQUARE-Yellow.pngPin A3: Analog input 3
SQUARE-Red.png5V Out: Low current output for sensor when used with A3
SQUARE-Black.pngGround (G): Common ground
Internal Pins / Connections
 Pin D14: Controls the tri-state buffer (IC3) on the ATMega328P Tx serial line (pulled-down)
Pin D7: Controls the tri-state buffer (IC4) on CH340E Tx / ATMega328P Rx serial line (pulled-up)
Pin D9: H-Bridge Input #1
Pin D10: H-Bridge Input #2
Pin D3: H-Bridge Input #3
Pin D11: H-Bridge Input #4
Pins A4: H-Bridge i2c (SDA = A4)
Pin D2: H-Bridge NSleep (set high to enable)
Pin D8: H-Bridge NFault

Wiring & Power Options



LSS Connectors: The board is meant to be powered from ONE of the two LSS connectors. Vin will supply the two on-board 5V regulators (logic and Vout) and to the Lynxmotion Smart Servos connected on the bus. Power will also be supplied to the h-bridge at the same voltage as the bus voltage.

Refer to LSS Voltage rating in LSS - Specifications


USB: Connecting only the USB will only provide voltage to the logic. It won't power the h-bridge chip.

**NOTE:** USB and Vin power source are isolated and there are no issues connecting both a USB and a powered LSS bus at the same time
Sample Wiring / Use

LSS-2MC on a bus, powered by an LSS-ADA

Lynxmotion Smart Servo is optional 

LSS-2MC on a bus, powered by an LSS-HUB 

Lynxmotion Smart Servo and LSS-2IO are optional 

Dual H-Bridge (DC Motors)

Sample Wiring / Use

Bipolar Stepper Motor

Sample Wiring / Use

Dimensions & Mounting

Created by Eric Nantel on 2021/04/06 10:51
Copyright RobotShop 2018