HD4074329S Renesas Electronics America, HD4074329S Datasheet - Page 51

• 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

Timer C (TCCL and TCRL: $00A, TCCU and TCRU: $00B): Eight-bit write-only timer load register
(TCRL and TCRU) and read-only timer counter (TCCL and TCCU) located at the same addresses. The
eight-bit configuration consists of lower and upper digits located at sequential addresses. The operation of
timer C is basically the same as that of timer B. A block diagram of timer C is shown in figure 28.
The auto-reload function and prescaler division ratio of timer C depend on the state of timer mode register
C (TMC). Timer C is initialized to the value set in TMC by software, then is incremented by one at each
clock input. If an input is applied to timer C after it has reached $FF, an overflow is generated. In this
case, if the auto-reload function is enabled, timer C is initialized to its initial value; if auto-reload is
disabled, the timer is initialized to $00. The overflow sets the timer C interrupt request flag (IFTC: $002,
bit 2).
Timer C also functions as a watchdog timer. If a program routine runs out of control and an overflow is
generated while the watchdog on (WDON) flag is set, the MCU is reset. This error can be detected by
having the program control timer C reset before timer C reaches $FF.
The WDON can only have 1 written to it; it is cleared to 0 only by MCU reset.
System
clock
ø
PER
Watchdog on
flag (WDON)
Prescaler S (PSS)
Selector
Clock
Figure 28 Timer C Block Diagram
Watchdog timer
controller
Free-running/
reload timer
control signal
register C upper
System reset signal
Timer load
(TCRU)
3
Timer/counter C
(TCC)
register C lower
Timer latch
Timer load
register C
(TCRL)
(TLC)
register C (TMC)
Timer mode
HD404328 Series
Interrupt request
flag of timer C
(IFTC)
Overflow
47