Clock Frequency And Instruction Execution Time; I/O Memory Of Oscillation Circuit - Epson S1C63358 Technical Manual

4.4.5 Clock frequency and instruction execution time

Table 4.4.5.1 shows the instruction execution time according to each frequency of the system clock.
Clock frequency
OSC1: 32.768 kHz
OSC1: 60 kHz
OSC3: 4 MHz

4.4.6 I/O memory of oscillation circuit

Table 4.4.6.1 shows the I/O address and the control bits for the oscillation circuit.
Register
Address
D3 D2
CLKCHG OSCC
FF00H
R/W
*1 Initial value at initial reset
*2 Not set in the circuit
*3 Constantly "0" when being read
VDC: CPU operating voltage switching register (FF00H•D0)
It is used to switch the operating voltage V
OSC1 oscillation circuit by mask option.
When "1" is written: 2.25 V (for OSC3 operation)
When "0" is written: 1.35 V (for OSC1 operation)
Reading: Valid
When switching the CPU system clock, the operating voltage V
the clock.
When switching from OSC1 to OSC3, first set V
then turn the OSC3 oscillation ON.
When switching from OSC3 to OSC1, set V
oscillation OFF.
When the CR oscillation circuit has been selected as the OSC1 oscillation circuit by mask option, setting
of this register does not affect the operating voltage V
At initial reset, this register is set to "0".
OSCC: OSC3 oscillation control register (FF00H•D2)
Controls oscillation ON/OFF for the OSC3 oscillation circuit.
When "1" is written: OSC3 oscillation ON
When "0" is written: OSC3 oscillation OFF
Reading: Valid
When it is necessary to operate the CPU at high speed, set OSCC to "1". At other times, set it to "0" to
reduce current consumption. Furthermore, when the crystal oscillation circuit has been selected as the
OSC1 oscillation circuit by mask option, it is necessary to switch the operating voltage V
the OSC3 oscillation circuit ON and OFF
At initial reset, this register is set to "0".
S1C63358 TECHNICAL MANUAL
CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (Oscillation Circuit)
Table 4.4.5.1 Clock frequency and instruction execution time
1-cycle instruction 2-cycle instruction 3-cycle instruction
61
33
0.5
Table 4.4.6.1 Control bits of oscillation circuit
∗1
D1 D0 Name Init
CLKCHG 0
0 VDC
OSCC 0
∗3 ∗2
0 –
R R/W
VDC 0
, when the crystal oscillation circuit has been selected as the
D1
to 1.35 V after switching to OSC1 and turning the OSC3
D1
Instruction execution time (µsec)
122
66
1
1 0
OSC3 OSC1 CPU clock switch
On Off OSC3 oscillation On/Off
Unused
2.25 V 1.35 V CPU operating voltage switch (1.35 V: OSC1, 2.25 V: OSC3)
should also be switched according to
D1
to 2.25 V. After that maintain 2.5 msec or more, and
D1
, and the V
D1 D1
EPSON
183
100
1.5
Comment
voltage is fixed at 2.25 V.
when turning
D1
33