4 MEMORY AND BUS
S1C17M12/M13 TECHNICAL MANUAL
Seiko Epson Corporation
4-7
(Rev. 1.2)
4.6 Control Registers
MISC System Protect Register
Register name
Bit
Bit name
Initial
Reset
R/W
Remarks
MSCPROT
15–0 PROT[15:0]
0x0000
H0
R/W –
Bits 15–0 PROT[15:0]
These bits protect the control registers related to the system against writings.
0x0096 (R/W):
Disable system protection
Other than 0x0096 (R/W): Enable system protection
While the system protection is enabled, any data will not be written to the affected control bits (bits
with “WP” or “R/WP” appearing in the R/W column).
MISC IRAM Size Register
Register name
Bit
Bit name
Initial
Reset
R/W
Remarks
MSCIRAMSZ
15–9 –
0x00
–
R
–
8
(reserved)
0
H0
R/WP Always set to 0.
7–3 –
0x04
–
R
–
2–0 IRAMSZ[2:0]
0x2
H0
R/WP
Bits 15–3 Reserved
Bits 2–0
IRAMSZ[2:0]
These bits set the internal RAM size that can be used.
Table 4.7.1 Internal RAM Size Selections
MSCIRAMSZ.IRAMSZ[2:0] bits
Internal RAM size
0x7–0x3
Reserved
0x2
2KB
0x1
1KB
0x0
512B
FLASHC Flash Read Cycle Register
Register name
Bit
Bit name
Initial
Reset
R/W
Remarks
FLASHCWAIT
15–9 –
0x00
–
R
–
8
(reserved)
0
H0
R/WP Always set to 0.
7–2 –
0x00
–
R
–
1–0 RDWAIT[1:0]
0x1
H0
R/WP
Bits 15–2 Reserved
Bits 1–0
RDWAIT[1:0]
These bits set the number of bus access cycles for reading from the Flash memory.
Table 4.7.2 Setting Number of Bus Access Cycles for Flash Read
FLASHCWAIT.RDWAIT[1:0] bits Number of bus Access cycles
System clock frequency
0x3
4
16.8 MHz (max.)
0x2
3
16.8 MHz (max.)
0x1
2
12.6 MHz (max.)
0x0
1
6.3 MHz (max.)
Note
: Be sure to set the FLASHCWAIT.RDWAIT[1:0] bits before the system clock is configured.