R01UH0092EJ0110 Rev.1.10
Page 474 of 807
Jul 31, 2012
M16C/64C Group
23. Serial Interface UARTi (i = 0 to 2, 5 to 7)
Figure 23.5
Transmit and Receive Operation during Clock Synchronous Serial I/O Mode
D0 D1 D2 D3 D4 D5 D6 D7
D0 D1 D2 D3 D4 D5 D6 D7
D0 D1 D2 D3 D4 D5 D6 D7
Tc
T
CLK
Pulse stops because the TE bit is set to 0
Set the data in the UiTB register.
Data is transferred from the UiTB register
to the UARTi transmit register.
T
C
= T
CLK
= 2(n + 1)/fj
fj: Frequency of UiBRG count source
(f1SIO, f2SIO, f8SIO, f32SIO)
n: Value set to the UiBRG register
Transmit/receive
clock
TE bit in the
UiC1 register
TI bit in the
UiC1 register
CLKi
TXDi
TXEPT flag in
the UiC0
register
High
Low
0
1
0
1
0
1
CTSi
IR bit in the
SiTIC register
0
1
Set to 0 by an interrupt request acknowledgment or by a program.
Pulse stops because a high-level signal
is applied to CTSi
1/fEXT
Set the dummy data in the UiTB
register.
CLKi
RXDi
RTSi
High
Low
0
1
0
1
0
1
RE bit in the
UiC1 register 0
1
Data is transferred from the UiTB register to the UARTi transmit register.
Read the UiRB register
Make sure the following conditions are met when input
to the CLKi pin before receiving data is high:
· The TE bit in the UiC1 register = 1 (transmit enabled)
· The RE bit in the UiC1 register = 1 (receive enabled)
· Write dummy data to the UiTB register
Data is transferred from the UARTi
receive register to the UiRB register
0
1
Set to 0 by an interrupt request acknowledgment or by a program.
D0 D1 D2 D3 D4 D5 D6 D7
D0 D1 D2 D3 D4 D5
D0 D1 D2 D3 D4 D5
D7
D6
0
1
D6
TE bit in the
UiC1 register
TI bit in the
UiC1 register
OER flag in the
UiRB register
IR bit in
SiRIC register
RI bit in the
UiC1 register
Received data is taken in
A low-level signal is applied when the UiRB register is read.
(1) Example of Transmit Timing (Internal Clock Selected)
(2) Example of Receive Timing (External Clock Selected)
i = 0 to 2, 5 to 7
The above assumes the following:
• The CKDIR bit in the UiMR register is 0 (internal clock).
• The CRD bit in the UiC0 register is 0 (
CTS
/
RTS
enabled), the CRS bit is 0 (
CTS
selected).
• The CKPOL bit in the UiC0 register is 0 (transmit data output at the falling edge and receive data
taken in at the rising edge of the transmit/receive clock).
• The UiIRS bit in the UiC1 or UCON register is 0 (an interrupt request occurs when the UiTB
register becomes empty).
The above assumes the following:
• The CKDIR bit in the UiMR register is 1 (external clock).
• The CRD bit in the UiC0 register is 0 (
CTS
/
RTS
enabled), the CRS bit is 1
(
RTS
selected).
• The CKPOL bit in the UiC0 register is 0 (transmit data output at the falling edge and
receive data taken in at the rising edge of the transmit/receive clock).
fEXT: Frequency of the external clock
i = 0 to 2, 5 to 7
Содержание M16C Series
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