DF3048BVX25V Renesas Electronics America, DF3048BVX25V Datasheet - Page 477

• Manufacturer Part Number: DF3048BVX25V
• Description: MCU 3/5V 128K PB-FREE 100-TQFP
• Manufacturer: Renesas Electronics America
• Series: H8® H8/300Hr

Specifications of DF3048BVX25V

• Core Processor: H8/300H
• Core Size: 16-Bit
• Speed: 25MHz
• Connectivity: SCI, SmartCard
• Peripherals: DMA, PWM, WDT
• Number Of I /o: 70
• Program Memory Size: 128KB (128K x 8)
• Program Memory Type: FLASH
• Ram Size: 4K x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 3.6 V
• Data Converters: A/D 8x10b; D/A 2x8b
• Oscillator Type: Internal
• Operating Temperature: -20°C ~ 75°C
• Package / Case: 100-TQFP, 100-VQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -

12.3
Operations when the WDT is used as a watchdog timer and as an interval timer are described
below.
12.3.1
Figure 12.4 illustrates watchdog timer operation. To use the WDT as a watchdog timer, set the
WT/IT and TME bits to 1 in TCSR. Software must prevent TCNT overflow by rewriting the
TCNT value (normally by writing H'00) before overflow occurs. If TCNT fails to be rewritten and
overflows due to a system crash etc., the chip is internally reset for a duration of 518 states.
The watchdog reset signal can be externally output from the RESO pin to reset external system
devices. The reset signal is output externally for 132 states. External output can be enabled or
disabled by the RSTOE bit in RSTCSR. Note that there is no RESO pin in the versions with on-
chip flash memory.
A watchdog reset has the same vector as a reset generated by input at the RES pin. Software can
distinguish a RES reset from a watchdog reset by checking the WRST bit in RSTCSR.
If a RES reset and a watchdog reset occur simultaneously, the RES reset takes priority.
H'FF
TCNT count
value
H'00
Internal
reset signal
RESO
Operation
Watchdog Timer Operation
Start
Figure 12.4 Watchdog Timer Operation
H'00 written
in TCNT
OVF = 1
WDT overflow
Rev. 3.00 Sep 27, 2006 page 449 of 872
132 states
Reset
518 states
TME set to 1
Section 12 Watchdog Timer
H'00 written
in TCNT
REJ09B0325-0300