6 CLOCK MANAGEMENT UNIT (CMU)
S1C33L26 TECHNICAL MANUAL
Seiko Epson Corporation
6-27
10.12 Maximum Frequency Change Width Settings
Table 6.
PLL output clock frequency f [MHz]
SSMCIDT[3:0]
f
≤
19.8
0xf
19.8 < f
≤
21.2
0xe
21.2 < f
≤
22.5
0xd
22.5 < f
≤
24.2
0xc
24.2 < f
≤
25.9
0xb
25.9 < f
≤
28.4
0xa
28.4 < f
≤
30.8
0x9
30.8 < f
≤
34.2
0x8
34.2 < f
≤
37.8
0x7
37.8 < f
≤
43.1
0x6
43.1 < f
≤
48.9
0x5
48.9 < f
≤
58.5
0x4
58.5 < f
≤
69.7
0x3
69.7 < f
≤
90.0
0x2
–
0x1
–
0x0
(Default: undefined)
Note: SSMCIDT[3:0] must be set according to the PLL output clock frequency as shown in Table
6.10.12. Using the SSCG with an improper setting may cause a malfunction of the IC.
CMU Write Protect Register (CMU_PROTECT)
Register name Address
Bit
Name
Function
Setting
Init. R/W
Remarks
CMU Write
Protect Register
(CMU_
PROTECT)
0x300110
(8 bits)
D7–0 CMUP[7:0] CMU register write-protect flag
Writing 10010110 (0x96)
removes the write protection of
the CMU registers (0x300100–
0x30010d).
Writing another value set the
write protection.
0x0 R/W
D[7:0]
CMUP[7:0]: CMU Register Write-Protect Flag Bits
Enables or disables write protection of the CMU control registers (0x300100–0x30010d).
0x96 (R/W):
Disable write protection
Other than 0x96 (R/W): Write-protect the register (default: 0x0)
Before altering any CMU control register, write data 0x96 to CMUP[7:0] to disable write protection. If
CMUP[7:0] is set to other than 0x96, even if an attempt is made to alter any CMU control register by
executing a write instruction, the content of the register will not be altered even though the instruction
may have been executed without a problem. Once CMUP[7:0] is set to 0x96, the CMU control registers
can be rewritten any number of times until being reset to other than 0x96. When rewriting the CMU
control registers has finished, CMUP[7:0] should be set to other than 0x96 to prevent accidental writing
to the CMU registers.