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Rev. 5.00, 09/03, page 254 of 760
Bits 5 to 3—Clock Select Bits (CKS2 to CKS0): Select the clock input to RTCNT. The source
clock is the external bus clock (CKIO). The RTCNT count clock is CKIO divided by the specified
ratio. RTCOR must be set before setting CKS2-CKS0.
Description
Bit 5: CKS2 Bit 4: CKS1 Bit 3: CKS0 Normal external bus clock
0 0 0 Clock input disabled
1 Bus clock (CKIO)/4
1 0 CKIO/16
1CKIO/64
100CKIO/256
1 CKIO/1024
1 0 CKIO/2048
1 CKIO/4096
Bit 2—Refresh Count Overflow Flag (OVF): Indicates when the number of refresh requests
indicated in the refresh count register (RFCR) exceeds the limit set in the LMTS bit in RTCSR.
Bit 2: OVF Description
0 RFCR has not exceeded the count limit value set in LMTS (Initial value)
Clearing condition: When 0 is written to OVF
1 RFCR has exceeded the count limit value set in LMTS
Setting condition: When the RFCR value has exceeded the count limit value
set in LMTS
*
Note: * Contents do not change when 1 is written to OVF.
Bit 1—Refresh Count Overflow Interrupt Enable (OVIE): Selects whether to suppress
generation of interrupt requests by the OVF bit in RTCSR when OVF is set to 1.
Bit 1: OVIE Description
0 Interrupt request by OVF is disabled (Initial value)
1 Interrupt request by OVF is enabled