29 MISC REGISTERS (MISC)
S1C33L26 TECHNICAL MANUAL
Seiko Epson Corporation
29-1
Misc Registers (MISC)
29
Notes: • The Misc registers at addresses 0x300010–0x300018 are write-protected. Before the Misc
registers can be rewritten, write protection of these registers must be removed by writing data
0x96 to PROT[7:0]/MISC_PROTECT register. Note that since unnecessary rewrites to the
Misc registers could lead to erratic system operation, PROT[7:0] should be set to other than
0x96 unless the Misc registers must be rewritten.
• PCLK1 must be supplied from the CMU to access the Misc registers.
For details of the clock control bit, see the “Clock Management Unit (CMU)” chapter.
RTC Wait Control
29.1
The MISC_RTCWT register contains RTCWT[2:0] to set the number of wait cycles to be inserted when accessing
the RTC registers. The number of wait cycles should be set according to the MCLK clock frequency.
1.1 RTCWT[2:0] (RTC Wait Cycle) Settings
Table 29.
RTCWT[2:0]
Number of wait cycles
MCLK frequency
0x7
7 cycles
f
MCLK
≤
60 MHz
0x6
6 cycles
0x5
5 cycles
0x4
4 cycles
0x3
3 cycles
0x2
2 cycles
0x1
1 cycle
0x0
0 cycles
Cannot be set
(Note)
(Default: 0x7)
Note: The S1C33L26 RTC cannot operate if RTCWT[2:0] is set to 0x0 (0 wait cycles).
Internal RAM Wait Control
29.2
The MISC_RAMWT register contains COREWT and BUSWT to set the number of wait cycles (in MCLK) to be
inserted when accessing IRAM (Area 0) and IVRAM (Area 3), respectively.
When the control bit is set to 1 (default), one wait cycle will be inserted when the IRAM or IVRAM is accessed.
When the control bit is set to 0, no wait cycle will be inserted.
If IVRAM is relocated to Area 0, the COREWT setting is ineffective.
2.1 COREWT (IRAM Wait Cycle) Settings
Table 29.
COREWT
Number of wait cycles
MCLK frequency
1
1 cycle
f
MCLK
≤
60 MHz
0
0 cycles
(Default: 1)
2.2 BUSWT (IVRAM Wait Cycle) Settings
Table 29.
BUSWT
Number of wait cycles
MCLK frequency
1
1 cycle
f
MCLK
≤
60 MHz
0
0 cycles
(Default: 1)