DF2437FV Renesas Electronics America, DF2437FV Datasheet - Page 473

• Manufacturer Part Number: DF2437FV
• Description: IC H8S/2437 MCU FLASH 128QFP
• Manufacturer: Renesas Electronics America
• Series: H8® H8S/2400r

Specifications of DF2437FV

• Core Processor: H8S/2600
• Core Size: 16-Bit
• Speed: 20MHz
• Connectivity: I²C, SCI
• Peripherals: POR, PWM, WDT
• Number Of I /o: 85
• Program Memory Size: 256KB (256K x 8)
• Program Memory Type: FLASH
• Ram Size: 16K x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 3.6 V
• Data Converters: A/D 16x10b
• Oscillator Type: Internal
• Operating Temperature: -20°C ~ 75°C
• Package / Case: 128-QFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -

14.7.4
When the external event signal is changed, the edge detection circuit may regard it as a rising or
falling edge. Table 14.4 shows the relationship between the timing at which the external event
signal is switched (bits IS2 to IS0 are rewritten) and operation of the edge detection circuit.
Rising and falling edges of the external event signal are detected by the edge detection circuit.
Thus, if the clock is changed when the old source is low and the new source is high, as in case no.
2 in table 14.4, the changeover is regarded as a rising edge and the TWCNT value is transferred to
TWICR during duty measurement. If the clock is changed when the old source is high and the new
source is low, as in case no. 3 in table 14.4, the changeover is regarded as a falling edge and duty
measurement is started or ended. To prevent incorrect operation, ensure that the IS bit should not
be rewritten during duty measurement.
Table 14.4 Switching of External Event Signal and Operation of Edge Detection Circuit
No.
1
2
Timing of Switchover by
Means of IS2 to IS0 Bits
Switching from
low to low
Switching from
low to high
Switching of External Event Signal and Operation of Edge Detection Circuit
Operation of Edge Detection Circuit
External event signal
External event signal
External event signal
External event signal
before switchover
before switchover
after switchover
after switchover
detection signal
detection signal
detection signal
detection signal
Falling edge
Falling edge
Rising edge
Rising edge
Switchover of IS bit
Rev.2.00 May. 28, 2009 Page 433 of 732
Switchover of IS bit
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REJ09B0059-0200
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