S1C6S3N2 TECHNICAL SOFTWARE
EPSON
II-25
CHAPTER 5: PERIPHERAL CIRCUITS (OSC3)
OSC3
S1C6S3A2 has two built-in oscillation circuits (OSC1 and
OSC3).
When processing of S1C6S3A2 requires high-speed opera-
tions, the CPU's operating clock should be switched from
OSC1 to OSC3.
5.2
OSC3 memory map
Table 5.2.1 I/O data memory map (OSC3)
OSC1
OFF
Input
Unused
CPU clock switch
OSC3 oscillator ON/OFF
I/O control register 1 (P10–P13)
OSC3
ON
Output
Address
Comment
Register
D3
D2
D1
D0
Name
SR
*1
1
0
0FEH
OSCC
IOC1
R
0
CLKCHG
OSCC
IOC1
–
0
0
0
*2
R/W
CLKCHG
0
*
1 Initial value at the time of initial reset
*
2 Not set in the circuit
*
3 Undefined
*
4 Reset (0) immediately after being read
*
5 Constantly "0" when being read
CLKCHG
: The CPU's clock switch (0FEH.D2)
The CPU's operation clock is selected with this register
(S1C6S3A2 only).
When "1" is written:
OSC3 is selected
When "0" is written:
OSC1 is selected
Read-out:
Available
This register cannot be controlled for S1C6S3N2/6S3L2/
6S3B2, so that OSC1 is selected regardless of the set value.
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