UART
UARTについて
http://www.altima.jp/column/fpga_edison/uart.html
UART / USART
https://www.youtube.com/watch?v=FQpbIvhY7es
UART = Universal Asyncronus Receiver-Transmitter
USART = Universal Syncronus / Asyncronus Receiver-Transmitter
RS-232
https://www.youtube.com/watch?v=XVEnxipCIJ0
RS-232 Recommended Standard
Tx <--> Rx
Tx = Transmmit Data Rx = Receive Data
DTR <--> DSR
DTR = Data Terminal Ready DSR = Data Set Ready
RST <--> CTS
RTS = Request To Send CTS = Carrier To Send
DCD = Data Carrier Detect RI = ??