4518 Datasheet, PDF (55/160 Pages) Renesas Technology Corp – SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

4518 Group
(5) How to use serial I/O
Figure 44 shows the serial I/O connection example. Serial I/O inter-
rupt is not used in this example. In the actual wiring, pull up the
wiring between each pin with a resistor. Figure 44 shows the data
transfer timing and Table 16 shows the data transfer sequence.
Master (clock control)
Slave (external clock)
D3
SCK
SOUT
SI N
(Bit 3)
00
(Bit 0)
11
Serial I/O control
register J1
Serial I/O port
SCK,SOUT,SIN
Instruction clock/8 selected
as synchronous clock
SRDY signal
D3
SCK
SI N
SOUT
(Bit 3)
11
(Bit 0)
11
Serial I/O control
register J1
Serial I/O port
SCK,SOUT,SIN
External clock selected
as synchronous clock
(Bit 3)
0✕
(Bit 0)
✕✕
Interrupt control
register V2
Serial I/O interrupt
enable bit
(SNZSI instruction valid)
(Bit 3)
0✕
(Bit 0)
✕✕
Interrupt control
register V2
Serial I/O interrupt
enable bit
(SNZSI instruction valid)
Fig. 44 Serial I/O connection example
✕: Set an arbitrary value.
Master
SOUT
SI N
SST instruction
M7’
S7’
M0
M1
M2
M3
M4
M5
M6
M7
S0
S1
S2
S3
S4
S5
S6 S7
SCK
Slave
SST instruction
SRDY signal
SOUT
SI N
S7’
M7’
S0
S1
S2
S3
S4
S5
S6
S7
M0
M1
M2
M3
M4
M5
M6 M7
M0–M7: Contents of master serial I/O register
S0–S7: Contents of slave serial I/O register
Rising of SCK: Serial input
Falling of SCK: Serial output
Fig. 45 Timing of serial I/O data transfer
Rev.3.01 2005.06.15 page 55 of 157
REJ03B0008-0301