HD4074329S Renesas Electronics America, HD4074329S Datasheet - Page 49

• 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

Timers
The MCU has two prescalers (S and W) and three timer/counters (A, B, and C).
Prescaler S: Eleven-bit counter that inputs a system clock signal. After being initialized to $000 by MCU
reset, prescaler S divides the system clock. Prescaler S keeps counting, except in watch and stop modes,
and at MCU reset. Of the prescaler S outputs, timer A input clock, timer B input clock, timer C input
clock, and serial interface transmit clock are selected by timer mode register A (TMA), timer mode register
B (TMB), timer mode register C (TMC), and the serial mode register (SMR).
Prescaler W: Five-bit counter that inputs the X1 input clock signal divided by eight. Prescaler W output
can be selected as a timer A input clock by timer mode register A (TMA).
Timer A: Eight-bit timer that can be used as a clock time-base (figure 26). It is initialized to $00 and
incremented at each input clock. If an input clock is applied to timer A after it has reached $FF, an
overflow that sets the timer A interrupt request flag (IFTA: $001, bit 2) is generated, and timer A restarts
from $00.
Timer A is used to generate regular interrupts (every 256 clocks) for measuring times between events. It
can also be used as a clock time-base when bit 3 of timer mode register A (TMA) is set to 1. The timer is
driven by the 32-kHz oscillator clock frequency divided by prescaler W, and the clock input to timer A is
controlled by TMA. In this case, prescaler W and timer A can be initialized to $00 by software.
32.768-kHz
oscillator
System
clock
1/4
ø
PER
1/2 tw
2 f
1/2
W
cyc
Figure 26 Timer A Block Diagram
tw
Prescaler S (PSS)
f
W
cyc
Selector
Prescaler W
Selector
(PSW)
Clock
3
Timer mode
counter A
register A
Timer A interrupt
(TCA)
Timer
(TMA)
request flag
HD404328 Series
(IFTA)
Overflow
45