Datasheet

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13.2.3 Reset Control/Status Register (RSTCSR)
The RSTCSR is an 8-bit readable and writable register. (The RSTCSR differs from other registers
in that it is more difficult to write. See section 13.2.4, Register Access, for details.) It controls
output of the internal reset signal generated by timer counter (TCNT) overflow and selects the
internal reset signal type. RSTCR is initialized to H'1F by input of a reset signal from the RES pin,
but is not initialized by the internal reset signal generated by the overflow of the WDT. It is
initialized to H'1F in standby mode.
Bit: 7 6 5 4 3 2 1 0
WOVF RSTE RSTS — — — — —
Initial value: 0 0 0 1 1 1 1 1
R/W: R/(W)
*
R/W R/W R R R R R
Note: * Only 0 can be written in bit 7 to clear the flag.
• Bit 7—Watchdog Timer Overflow Flag (WOVF): Indicates that the TCNT has overflowed
(H'FF–H'00) in the watchdog timer mode. It is not set in the interval timer mode.
Bit 7: WOVF Description
0 No TCNT overflow in watchdog timer mode (initial value)
Cleared when software reads WOVF, then writes 0 in WOVF
1 Set by TCNT overflow in watchdog timer mode
• Bit 6—Reset Enable (RSTE): Selects whether to reset the chip internally if the TCNT
overflows in the watchdog timer mode.
Bit 6: RSTE Description
0 Not reset when TCNT overflows (initial value). LSI not reset internally,
but TCNT and TCSR reset within WDT.
1 Reset when TCNT overflows
• Bit 5—Reset Select (RSTS): Selects the type of internal reset generated if the TCNT overflows
in the watchdog timer mode.
Bit 5: RSTS Description
0 Power-on reset (initial value)
1 Manual reset
• Bits 4–0—Reserved: These bits always read as 1. The write value should always be 1.