M37754 Mitsubishi, M37754 Datasheet - Page 54

• Manufacturer Part Number: M37754
• Description: SINGLE-CHIP 16BIT CMOS MICROCOMPUTER
• Manufacturer: Mitsubishi

Transmission
Transmission is started when bit 0 (TEi flag) of UARTi Transmit/Re-
ceive control register 1 is “1”, bit 1 (TIi flag) is “0”, and CTSi input is
“L” if CTSi input is selected. As shown in Figures 65 and 66, data is
output from the T
4 to 6 of UARTi Transmit/Receive mode register. The data is output
from the least significant bit.
The TIi flag indicates whether the transmit buffer is empty or not. It is
cleared to “0” when data is written in the transmit buffer, and is set to
“1” when the contents of the transmit buffer register is transferred to
the transmit register.
When the transmit register becomes empty after the contents has
been transmitted, data is transferred automatically from the transmit
buffer register to the transmit register if the next transmit start condi-
tion is satisfied.
Fig. 65 Transmit timing example when 8-bit asynchronous communication with parity and 1 stop bit selected
Fig. 66 Transmit timing example when 9-bit asynchronous communication with no parity and 2 stop bits selected
54
____
Transmission clock
TE
TI
CTS
T
T
T
Transmission clock
TE
TI
T
T
T
ENDi
X
X
ENDi
X
X
i
i
D
EPTY
i
D
EPTY
i
i
i
i
i
i
X
Di pin with the stop bit or parity bit specified by bits
Start bit
Written in transmit buffer register
Start bit
Written in transmit buffer register
ST
ST
D
D
0
0
D
1
D
1
D
D
2
2
D
(1/Pf
(1/Pf
3
D
3
D
i
D
4
i
or 1/f
or 1/f
4
M37754M8C-XXXGP, M37754M8C-XXXHP
D
____
D
5
EXT
5
EXT
D
6
D
)
)
6
D
Parity bit Stop bit
(n
(n
D
7
7
P SP ST D
Stop bit Stop bit
1)
1)
D
8
16
Transmit register
SP
16
SP
____
Once transmission has started, the TEi flag, TIi flag, and CTSi signal
(if CTSi input is selected ) are ignored until data transmission is com-
pleted.
Therefore, transmission does not stop until it completes event if the
TEi flag is cleared during transmission.
The transmission start condition indicated by TEi flag, TIi flag, and
CTSi is checked while the T
Therefore, data can be transmitted continuously if the next transmis-
sion data is written in the transmit buffer register and TIi flag is
cleared to “0” before the T
Bit 3 (T
changes to “1” at the next cycle just after the T
and changes to “0” when transmission starts. Therefore, this flag can
be used to determine whether data transmission is completed.
When the TIi flag changes from “0” to “1”, the interrupt request bit of
the UARTi transmit interrupt control register is set to “1”.
Transmit register
____
M37754S4CGP, M37754S4CHP
ST D
0
D
1
X
0
EPTYi flag) of UARTi Transmit/Receive control register 0
D
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
D
2
1
Transmit
buffer register
D
3
D
2
D
Transmit
buffer register
D
4
3
D
5
D
MITSUBISHI MICROCOMPUTERS
4
D
6
D
END
5
D
END
D
7
i signal goes “H”.
6
P SP
i signal shown in Figure 65 is “H”.
D
7
D
8
SP SP
Stopped because TE
Stopped because TE
END
ST D
i signal goes “H”
ST D
0
____
0
D
1
D
i
1
i
= “0”
= “0”
D
2