m3819 Renesas Electronics Corporation., m3819 Datasheet - Page 40

• Manufacturer Part Number: m3819
• Description: Mitsubishi 8-bit Single-chip Microcomputer 740 Family / 38000 Series
• Manufacturer: Renesas Electronics Corporation.

(1) Serial I/O Ordinary Mode
Fig. 15 Serial I/O timing in the serial I/O ordinary mode (for LSB first)
(2) Serial I/O Automatic Transfer Mode
Serial I/O Automatic Transfer Control Register
The serial I/O automatic transfer control register (address 001A
consists of 4 bits which control automatic transfer.
26
Either an internal clock or an external clock can be selected
as the synchronous clock for serial I/O transfer. A dedicated
divider is built in as the internal clock for selecting of 6 clocks.
If internal clock is selected, transfer starts with a write signal
to a serial I/O register (addresses 001B
0026
to high impedance state.
The serial I/O1 has the automatic transfer function. For auto-
matic transfer, switch to the automatic transfer mode by
setting the serial I/O automatic transfer control register (ad-
dress 001A
The following memory spaces and registers used to enable
automatic transfer mode:
• 32-byte serial I/O automatic transfer RAM
• A serial I/O automatic transfer control register
• A serial I/O automatic transfer interval register
• A serial I/O automatic transfer data pointer
When using serial I/O automatic transfer, set the serial I/O1
control register (address 0019
rial I/O ordinary mode. However, note that when external
clock is selected, port P6
ting the bit 4 (the S
control register to “1”.
16
). After 8 bits have been transferred, the S
16
Note :
).
Serial I/O register
Serial I/O output
If internal clock is selected, the S
at the completion of data transfer.
Receive enable
Serial I/O input
RDY1
Transfer clock
Synchronous
write signal
output selection bit ) of the serial I/O1
7
signal
clock
becomes the CS input pin by set-
S
S
OUT
RDY
S
IN
16
) in the same way as the se-
(SIOAC) 001A
16
OUT
, 001F
OUT
pin goes to high impedance state
pin goes
16
, or
D
16
16
0
)
D
1
Fig. 16 Structure of serial I/O automatic transfer control register
b7
D
2
If external clock is selected, control the clock externally be-
cause the contents of the serial I/O register continue to shift
during inputting the transfer clock. In this case, note that the
S
tion of data transfer.
The interrupt request bit is set at the completion of the trans-
fer of 8 bits, regardless of whether the internal or external
clock is selected.
OUT
D
pin does not go to high impedance state at the comple-
3
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
D
4
D
MITSUBISHI MICROCOMPUTERS
b0
5
Serial I/O automatic transfer control register
(SIOAC : address 001A
Automatic transfer control bit
0 : Serial I/O ordinary mode
(serial I/O1 interrupt)
1 : Automatic transfer mode
(serial I/O1 automatic transfer interrupt)
Automatic transfer start bit
0 : Transfer completion
1 : Transferring(starts by writing “1”)
Transfer mode switch bit
0 : Fullduplex(transmit and receive)
1 : Transmit-only mode
Synchronous clock output
pin selection bit
0 : S
1 : S
Not used (return “0” when read)
D
mode
6
CLK11
CLK12
Interrupt request bit set
D
7
(Note)
3819 Group
16
)