2. Microcontrollers - leggedrobotics/hardware_time_sync GitHub Wiki

A Microcontroller Unit (MCU) is used to create the trigger signal and record the time.

Selecting an MCU

It's important to select a microcontroller with many high resolution timers. Triggering sensors should be done in an ISR configured for one of these timers.

Microcontroller	Logic Voltage	Timers (8b/16b/32b)	SRAM
Arduino Uno	5v	2/1/0	2k
Arduino Mega	5v	2/4/0	8k
Arduino Due	3.3v	0/0/9	96k
Teensy 3.2	3.3v	0/3/4	64k

Serial communication

Data will be passed over serial from the MCU, likely through a USB converter. The baud rate must be as high as possible to pass along the time info at a reasonable rate.

rosserial_python

A server must run on the PC side to communicate with the MCU over USB and relay the ROS messages. For this we use rosserial_python which supports service calls and is more stable than rosserial_server.