Implement the xv-11 lidar data receiving tesk:

1.maintain a usart task to check checksum and index
of the current received packet.

2.implement the checksum function refer to :
http://xv11hacking.wikispaces.com/LIDAR+Sensor

3.stored the correct packet to the 2D array lidarBuffer.
LidarPacketNumber:90 (receive 90 packet per cycle.)
LidarPacketSize:22 (each packet formed by 22 bytes)

Note:disable the usart interrupt during checking for the current packet.