HD4074329S Renesas Electronics America, HD4074329S Datasheet - Page 55

• Manufacturer Part Number: HD4074329S
• Description: MCU 4-Bit HMCS400 CISC 20KB EPROM 3.3V/5V 64-Pin SDIP
• Manufacturer: Renesas Electronics America

Specifications of HD4074329S

• Package: 64SDIP
• Family Name: HMCS400
• Maximum Speed: 4.5 MHz
• Ram Size: 268 Byte
• Program Memory Size: 20 KB
• Operating Supply Voltage: 3.3|5 V
• Data Bus Width: 4 Bit
• Program Memory Type: EPROM
• Number Of Programmable I/os: 35
• On-chip Adc: 4-chx8-bit
• Operating Temperature: -20 to 75 °C
• Number Of Timers: 3

Serial Interface
The MCU has a clock-synchronous serial interface which transmits and receives 8-bit data.
The serial interface consists of a serial data register (SR), serial mode register (SMR), port mode register A
(PMRA), octal counter, and selector, as shown in figure 29. The R1
controlled by writing data to the SMR. The transmit clock shifts the contents of the SR, which can be read
and written to by software, before transmission starts between two MCUs.
The serial interface is activated by the STS instruction. The octal counter is reset to 000 by this instruction,
it starts counting at the falling edge of the transmit clock (SCK), and it increments at the rising edge of the
clock. A serial interrupt request flag is set when the eighth transmit clock signal is input (the serial
interface is reset) or when serial transmission is discontinued (the octal counter is reset).
Serial Mode Register (SMR: $005): Four-bit write-only register that controls the R1
clock, and prescaler division ratio as shown in figure 30. Writing to this register initializes the serial
interface.
A write signal input to the serial mode register discontinues the input of the transmit clock to the serial data
register and octal counter. Therefore, if a write is performed during data transmission, the octal counter is
reset to 000 to stop transmission, and, at the same time, the serial interrupt request flag is set.
SCK
System
SO
SI
clock
ø
PER
controller
I/O
Prescaler S (PSS)
Figure 29 Serial Interface Block Diagram
Selector
Clock
counter (OC)
1/2
Octal
3
0
/SCK pin and the transmit clock are
Serial interrupt
register (SR)
Serial mode
request flag
Serial data
register
(SMR)
(IFS)
HD404328 Series
Transfer
control
signal
0
/SCK pin, transmit
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