M16C6K9 Datasheet, PDF (117/292 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)
The transfer clock stops momentarily as CTS is “H” when the stop bit is checked.
Tc
The transfer clock starts as the transfer starts immediately CTS changes to “L”.
Transfer clock
Transmit enable
“1”
bit(TE)
“0”
Transmit buffer
“1”
empty flag(TI)
“0”
“H”
CTSi
“L”
TxDi
Transmit register “1”
empty flag (TXEPT)
“0”
Transmit interrupt ^{“1”}
request bit (IR)
“0”
Data is set in UARTi transmit buffer register.
Transferred from UARTi transmit buffer register to UARTi transmit register
Start
bit
Parity
bit
ST D0 D1 D2 D3 D4 D5 D6 D7 P
Stop
bit
Stopped because transmit enable bit = “0”
SP ST D0 D1 D2 D3 D4 D5 D6 D7 P SP
ST D0 D1
Shown in ( ) are bit symbols.
The above timing applies to the following settings :
• Parity is enabled.
• One stop bit.
• CTS function is selected.
• Transmit interrupt factor selection bit = “1”.
Cleared to “0” when interrupt request is accepted, or cleared by software
Tc = 16 (n + 1) / fi or 16 (n + 1) / fEXT
fi : frequency of BRGi count source (f1, f8, f32)
fEXT : frequency of BRGi count source (external clock)
n : value set to BRGi
• Example of transmit timing when transfer data are 9 bits long (parity disabled, two stop bits)
Tc
Transfer clock
Transmit enable ^{“1”}
bit(TE)
“0”
Transmit buffer
“1”
empty flag(TI)
“0”
TxDi
Transmit register ^{“1”}
empty flag (TXEPT) _{“0”}
Transmit interrupt ^{“1”}
request bit (IR)
“0”
Data is set in UARTi transmit buffer register
Start
bit
Transferred from UARTi transmit buffer register to UARTi transmit register
Stop Stop
bit bit
ST D0 D1 D2 D3 D4 D5 D6 D7 D8 SP SP ST D0 D1 D2 D3 D4 D5 D6 D7 D8 SPSP ST D0 D1
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 disabled.
• Two stop bits.
• CTS function is disabled.
• Transmit interrupt factor selection bit = “0”.
Tc = 16 (n + 1) / fi or 16 (n + 1) / fEXT
fi : frequency of BRGi count source (f1, f8, f32)
fEXT : frequency of BRGi count source (external clock)
n : value set to BRGi
Fig.GA-16 Typical transmit timings in UART mode
Rev.1.00 Jun 06, 2003 page 117 of 290