user manual

Rev.1.02 Jul 01, 2005 page 145 of 314
REJ09B0126-0102
M16C/6N Group (M16C/6NL, M16C/6NN) 14. Serial I/O
Under development
This document is under development and its contents are subject to change.
(1) Example of Transmit Timing when Transfer Data is 8-bit Long (parity enabled, one stop bit)
(2) Example of Transmit Timing when Transfer Data is 9-bit Long (parity disabled, two stop bits)
Figure 14.17 Transmit Operation
Start
bit
Parity
bit
TXDi
CTSi
"1"
"0"
"1"
"L"
"H"
"0"
"1"
TC = 16 (n + 1) / fj or 16 (n + 1) / fEXT
fj : frequency of UiBRG count source (f1SIO, f2SIO, f8SIO, f32SIO)
fEXT : frequency of UiBRG count source (external clock)
n : value set to UiBRG
i = 0 to 2
"0"
"1"
TXDi
"0"
"1"
"0"
"1"
"0"
"1"
Transfer clock
TC
"0"
"1"
TC
Transfer clock
D0
D1
D2
D3
D4
D5
D6
D7
ST
P
D0
D1
D2
D3
D4
D5
D6
D7
SP
ST
P
SP
D0
D1
ST
Stop
bit
Start
bit
The transfer clock stops momentarily as CTS
i is "H" when the stop bit is checked.
The transfer clock starts as the transfer starts immediately CTSi changes to "L".
D0
D1
D2
D3
D4
D5
D6
D7
ST
SP
D8
D0
D1
D2
D3
D4
D5
D6
D7
ST
D8
D0
D1
ST
SPSP
Stop
bit
Stop
bit
"0"
SP
Stopped pulsing
because the TE bit
= 0
Write data to the UiTB register
TE bit in
UiC1 register
TI bit in
UiC1 register
TXEPT bit in
UiC0 register
IR bit in
SiTIC register
Transferred from UiTB register to UARTi transmit register
The above timing diagram applies to the case where the register bits are set
as follows:
PRYE bit in UiMR register = 1 (parity enabled)
STPS bit in UiMR register = 0 (1 stop bit)
CRD bit in UiC0 register = 0 (CTS/RTS enabled), and CRS bit = 0 (CTS selected)
UilRS bit = 1 (an interrupt request occurs when transmit completed):
U0IRS bit is bit 0 in UCON register
U1IRS bit is bit 1 in UCON register
U2IRS bit is bit 4 in U2C1 register
Set to "0" by an interrupt request acknowledgement or by program
TE bit in
UiC1 register
TI bit in
UiC1 register
TXEPT bit in
UiC0 register
IR bit in
SiTIC register
Set to "0" by an interrupt request acknowledgement or by program
Write data to the UiTB register
Transferred from UiTB register to UARTi
transmit register
TC = 16 (n + 1) / fj or 16 (n + 1) / fEXT
fj : frequency of UiBRG count source (f1SIO, f2SIO, f8SIO, f32SIO)
fEXT: frequency of UiBRG count source (external clock)
n : value set to UiBRG
i = 0 to 2
The above timing diagram applies to the case where the register bits are set
as follows:
PRYE bit in UiMR register = 0 (parity disabled)
STPS bit in UiMR register = 1 (2 stop bits)
CRD bit in UiC0 register = 1 (CTS/RTS disabled)
UilRS bit = 0 (an interrupt request occurs when transmit buffer becomes empty):
U0IRS bit is bit 0 in UCON register
U1IRS bit is bit 1 in UCON register
U2IRS bit is bit 4 in U2C1 register