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Interval Timer: When PSRAME = 0 and DRAME = 0, the refresh controller operates as an
interval timer. After setting RTCOR, select an input clock in RTMCSR and set the CMIE bit to 1.
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CMI interrupts will be requested at compare match intervals determined by RTCOR and bits
CKS2 to CKS0 in RTMCSR.
When setting RTCOR, RTMCSR, and RFSHCR, make sure that PSRAME = 0 and DRAME = 0.
Writing is disabled when either of these bits is set to 1.
7.3.2 DRAM Refresh Control
Refresh Request Interval and Refresh Cycle Execution: The refresh request interval is
determined by the settings of RTCOR and bits CKS2 to CKS0 in RTMCSR. Figure 7-2 illustrates
the refresh request interval.
RTCOR
H'00
Refresh request
Refresh requests are generated at regular intervals as shown in figure 7-2, but the refresh cycle is
not actually executed until the refresh controller gets the bus right.
Table 7-4 summarizes the relationship among area 3 settings, DRAM read/write cycles, and
refresh cycles.
RTCNT
Figure 7-2 Refresh Request Interval (RCYCE = 1)
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