R8C/13 Group
13.2 Clock Asynchronous Serial I/O (UART) Mode
• Example of transmit timing when transfer data is 8 bits long (parity enabled, one stop bit)
Tc
Transfer clock
“1”
“0”
UiC1 register
TE bit
Write data to UiTB register
“1”
“0”
UiC1 register
TI bit
Transferred from UiTB register to UARTi transmit register
Stopped pulsing
because the TE bit
= “0”
Start
bit
ParityStop
bit bit
ST
TxDi
D0
D1
ST
D0
D3
D7
ST
D0
D3
D7
D1
D2
D4
D5
D6
P
SP
D1
D2
D4
D5
D6
P SP
UiC0 register
TXEPT bit
“1”
“0”
“1”
“0”
SiTIC register
IR bit
Set to “0” when interrupt request is accepted, or set by a program
Tc = 16 (n + 1) / fj or 16 (n + 1) / fEXT
The above timing diagram applies to the case where the register bits
are set as follows:
• UiMR register PRYE bit = 1 (parity enabled)
• UiMR register STPS bit = 0 (1 stop bit)
fj: frequency of UiBRG count source (f1SIO, f8SIO, f32SIO
EXT: frequency of UiBRG count source (external clock)
n: value set to UiBRG
i: 0, 1
)
f
• UiIRS bit = 1 (an interrupt request occurs when transmit completed):
• Example of transmit timing when transfer data is 9 bits long (parity disabled, two stop bits)
Tc
Transfer clock
“1”
“0”
“1”
UiC1 register
TE bit
Write data to UiTB register
UiC1 register
TI bit
“0”
Transferred from UiTB register to UARTi
transmit register
Stop Stop
bit bit
Start
bit
TxDi
ST
ST
D0
D1
D2
D3
D4
D5
D6
D7
D
8
SPSP ST
D0
D1
D2
D3
D4
D5
D6
D7
D
8
SPSP
D0
D1
“1”
“0”
UiC0 register
TXEPT bit
SiRIC register
IR bit
“1”
“0”
Set to “0” when interrupt request is accepted, or set by a program
The above timing diagram applies to the case where the register
bits are set as follows:
• UiMR register PRYE bit = 0 (parity disabled)
• UiMR register STPS bit = 1 (2 stop bits)
• UiIRS bit = 0 (an interrupt request occurs when transmit buffer
becomes empty)
Tc = 16 (n + 1) / fj or 16 (n + 1) / fEXT
fj: frequency of UiBRG count source (f1SIO, f8SIO, f32SIO
EXT: frequency of UiBRG count source (external clock)
n: value set to UiBRG
i: 0, 1
)
f
Figure 13.9 Transmit Operation
Rev.1.20 Jan 27, 2006 page 121 of 205
REJ09B0111-0120
RENESAS [ RENESAS TECHNOLOGY CORP ]
