4509 Datasheet, PDF (43/142 Pages) Renesas Technology Corp – SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

4509 Group
SERIAL INTERFACE
The 4509 Group has a built-in clock synchronous serial interface
which can serially transmit or receive 8-bit data.
Serial interface consists of;
• Serial interface register SI
• Serial interface control register J1
• Serial interface transmit/receive completion flag (SIOF)
• Serial interface counter
Registers A and B are used to perform data transfer with internal
CPU.
The pin functions of the serial interface pins can be set with the reg-
ister J1.
Table 14 Serial interface pins
Pin
P02/SCK
P01/SOUT
P03/SIN
Pin function when selecting serial interface
Clock I/O (SCK)
Serial data output (SOUT)
Serial data input (SIN)
Note: Even when the SIN pin function is used, the I/O of port P00 is valid.
Even when the SOUT pin function is used, the input of port P01 is valid.
The input of P02 can be used even when SCK is used. Be careful when
using inputs of both SCK and P02 since the input threshold value of SCK
pin is different from that of port P02.
1/8
1/4
INSTCK
1/2
P02/SCK ^SCK
P01/SOUT ^SOUT
J13J12
00
01
10
11
Synchronous
circuit
Serial interface counter (3)
QS
R
SIN
P00/SIN
J11 J10
MSB Serial interface register (8) LSB
TABSI
TSIAB
TABSI
Register B (4) Register A (4)
SIOF
Serial
interface
interrupt
SST
instruction
Internal reset signal
Fig. 36 Serial interface structure
Table 15 Serial interface control register
Serial interface control register J1
at reset : 00002
at RAM back-up : state retained
J13 J12
J13
00
Serial interface synchronous clock
J12
selection bits
01
10
11
J11 J10
J11
00
01
J10
Serial interface port function selection bits _{1 0}
11
Note: “R” represents read enabled, and “W” represents write enabled.
Synchronous clock
Instruction clock (INSTCK) divided by 8
Instruction clock (INSTCK) divided by 4
Instruction clock (INSTCK) divided by 2
External clock (SCK input)
Port function
P00, P01,P02 selected/SIN, SOUT, SCK not selected
P00, SOUT, SCK selected/SIN, P01, P02 not selected
SIN, P01, SCK selected/P00, SOUT, P02 not selected
SIN, SOUT, SCK selected/P00, P01,P02 not selected
R/W
TAJ1/TJ1A
Rev.1.02 2006.12.22 page 43 of 140
REJ03B0147-0102