S1C6S3N2 TECHNICAL HARDWARE
EPSON
I-29
CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Oscillation Circuit)
Table 4.3.1 Control bits of oscillation circuit and prescaler
Control of oscillation
circuit
Table 4.3.1 lists the control bits and their addresses for the
oscillation circuit.
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
Controls oscillation ON/OFF for the OSC3 oscillation circuit.
(S1C6S3A2 only.)
When "1" is written :
The OSC3 oscillation ON
When "0" is written :
The OSC3 oscillation OFF
Read-out :
Valid
When it is necessary to operate the CPU of the S1C6S3A2 at
high speed, set OSCC to "1". At other times, set it to "0" to
lessen the current consumption.
For the S1C6S3N2, 6S3L2 and 6S3B2, keep OSCC set to
"0".
At initial reset, OSCC is set to "0".
The CPU's operation clock is selected with this register.
(S1C6S3A2 only.)
When "1" is written :
OSC3 clock is selected
When "0" is written :
OSC1 clock is selected
Read-out :
Valid
When the S1C6S3A2's CPU clock is to be OSC3, set
CLKCHG to "1"; for OSC1, set CLKCHG to "0". This register
cannot be controlled for the S1C6S3N2, 6S3L2 and 6S3B2,
so that OSC1 is selected no matter what the set value.
OSCC:
OSC3 oscillation control
(0FEH·D1)
CLKCHG:
The CPU's clock switch
(0FEH·D2)
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