M16C6K9 Datasheet, PDF (118/292 Pages) Renesas Technology Corp – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

M16C/6K9 Group
Clock asynchronous serial I/O (UART) mode
• Example of transmit timing when transfer data are 8 bits long (parity enabled, one stop bit)
Tc
Transfer clock
Transmit enable
“1”
bit(TE)
“0”
Transmit buffer
“1”
empty flag(TI)
“0”
TxD2
Transmit register “1”
empty flag (TXEPT)
“0”
Transmit interrupt ^{“1”}
request bit (IR)
“0”
Data is set in USAR2 transmit buffer register Note1
Transferred from UART2 transmit buffer register to UART2 transmit register
Start
bit
Parity Stop
bit bit
ST D0 D1 D2 D3 D4 D5 D6 D7 P SP
ST D0 D1 D2 D3 D4 D5 D6 D7 P SP
Cleared to “0” when interrupt request is accepted, or cleared by software
Shown in ( ) are bit symbols.
The above timing applies to the following settings :
• Parity is enabled.
• One stop bit.
• Transmit interrupt factor selection bit = “1”.
Tc = 16 (n + 1) / fi
fi : frequency of BRGi count source (f1, f8, f32)
n : value set to BRGi
Note1. According to the above timing, the transmission is started by the timing of BRG overflow after writing to the transmit buffer.
Fig.GA-17 Typical transmit timings in UART mode (UART2)
Rev.1.00 Jun 06, 2003 page 118 of 290