HD64F2623FA20J Renesas Electronics America, HD64F2623FA20J Datasheet - Page 438

• Manufacturer Part Number: HD64F2623FA20J
• Description: IC H8S MCU FLASH 256K 100-QFP
• Manufacturer: Renesas Electronics America
• Series: H8® H8S/2600r

Specifications of HD64F2623FA20J

• Core Processor: H8S/2600
• Core Size: 16-Bit
• Speed: 20MHz
• Connectivity: CAN, SCI, SmartCard
• Peripherals: POR, PWM, WDT
• Number Of I /o: 53
• Program Memory Size: 256KB (256K x 8)
• Program Memory Type: FLASH
• Ram Size: 12K x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 3.6 V
• Data Converters: A/D 16x10b; D/A 2x8b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 100-QFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -

Section 12 Watchdog Timer
12.3
12.3.1
To use the WDT as a watchdog timer, set the WT/IT bit in TCSR and TME bit to 1. Software
must prevent TCNT overflows by rewriting the TCNT value (normally be writing H'00) before
overflows occurs. This ensures that TCNT does not overflow while the system is operating
normally. If TCNT overflows without being rewritten because of a system crash or other error, in
the WDT0 the WDTOVF signal is output. This is shown in figure 12.4 (a). This WDTOVF signal
can be used to reset the system. The WDTOVF signal is output for 132 states when RSTE = 1, and
for 130 states when RSTE = 0.
If TCNT overflows when 1 is set in the RSTE bit in RSTCSR, a signal that resets the chip
internally is generated at the same time as the WDTOVF signal. This reset can be selected as a
power-on reset or a manual reset, depending on the setting of the RSTS bit in RSTCSR. The
internal reset signal is output for 518 states.
If a reset caused by a signal input to the RES pin occurs at the same time as a reset caused by a
WDT overflow, the RES pin reset has priority and the WOVF bit in RSTCSR is cleared to 0.
In the case of WDT1, the chip is reset, or an NMI interrupt request is generated, for 516 system
clock periods (516 ) (515 or 516 states when the clock source is SUB (PSS = 1)). This is
illustrated in figure 12.4 (b).
An NMI request from the watchdog timer and an interrupt request from the NMI pin are both
treated as having the same vector. So, avoid handling an NMI request from the watchdog timer
and an interrupt request from the NMI pin at the same time.
Rev. 5.00 Jan 10, 2006 page 412 of 1042
REJ09B0275-0500
Operation
Watchdog Timer Operation