res=((USART2_BT_BUF[4]<<8)|USART2_BT_BUF[3])
USART2_BT_BUF[3] is the high eight bits
USART2_BT_BUF[4] is the bottom eight bits
res=((USART2_BT_BUF[4]<<8)|USART2_BT_BUF[3])
USART2_BT_BUF[3] is the high eight bits
USART2_BT_BUF[4] is the bottom eight bits