M30218 Datasheet, PDF (100/179 Pages) Mitsubishi Electric Semiconductor – M30218 Group

Clock asynchronous serial I/O (UART) mode
Mitsubishi microcomputers
M30218 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
• Example of transmit timing when transfer data is 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 enablee ^{“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 Stop
bit bit
Stopped pulsing because transmit enable bit = “0”
ST D0 D1 D2 D3 D4 D5 D6 D7 P 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 cause select bit = “1”.
Cleared to “0” by software, or when an interrupt request is accepted.
Tc = 16 (n + 1) / fi or 16 (n + 1) / fEXT
fi : frequency of BRGi's count source (f1, f8, f32)
fEXT : frequency of BRGi's count source (external clock)
n : value set to BRGi
• Example of transmit timing when transfer data is 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
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
Transmit register ^{“1”}
empty flag (TXEPT)
“0”
Transmit interrupt ^{“1”}
request bit (IR)
“0”
Cleared to “0” by software, or when an interrupt request is accepted.
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 causes select bit = “0”.
Tc = 16 (n + 1) / fi or 16 (n + 1) / fEXT
fi : frequency of BRGi's count source (f1, f8, f32)
fEXT : frequency of BRGi's count source (external clock)
n : value set to BRGi
Figure GA-12. Typical transmit timings in UART mode
99