DF36912GFH Renesas Electronics America, DF36912GFH Datasheet - Page 225

• Manufacturer Part Number: DF36912GFH
• Description: MCU 3/5V 8K 32-LQFP
• Manufacturer: Renesas Electronics America
• Series: H8® H8/300H Tinyr

Specifications of DF36912GFH

• Core Processor: H8/300H
• Core Size: 16-Bit
• Speed: 12MHz
• Connectivity: I²C, SCI
• Peripherals: LVD, POR, PWM, WDT
• Number Of I /o: 18
• Program Memory Size: 8KB (8K x 8)
• Program Memory Type: FLASH
• Ram Size: 1.5K x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 5.5 V
• Data Converters: A/D 4x10b
• Oscillator Type: Internal
• Operating Temperature: -20°C ~ 75°C
• Package / Case: 32-LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -

13.3
The watchdog timer is provided with an 8-bit counter. After the reset state is released, TCWD
starts counting up. When the TCWD count value overflows H'FF, an internal reset signal is
generated. The internal reset signal is output for a period of 256
writable counter, it starts counting from the value set in TCWD. An overflow period in the range
of 1 to 256 input clock cycles can therefore be set, according to the TCWD set value. When the
watchdog timer is not used, stop TCWD counting by writing 0 to B2WI and WDON
simultaneously while the TCSRWE bit in TCSRWD is set to 1. (To stop the watchdog timer, two
write accesses to TCSRWD are required.)
Figure 13.2 shows an example of watchdog timer operation.
Example:
Operation
Internal reset
signal
count value
TCWD
With 30ms overflow period when
Therefore, 256 – 15 = 241 (H'F1) is set in TCW.
H'FF
H'00
4
8192
10
H'F1
Figure 13.2 Watchdog Timer Operation Example
6
30
H'F1 written
to TCWD
10
–3
= 14.6
H'F1 written to TCWD
= 4 MHz
Rev. 3.00 Sep. 14, 2006 Page 195 of 408
256 φ
RC
clock cycles. As TCWD is a
Reset generated
RC
TCWD overflow
clock cycles
Section 13 Watchdog Timer
REJ09B0105-0300