RL78/G1P
CHAPTER 5 CLOCK GENERATOR
R01UH0895EJ0100 Rev.1.00
120
Nov 29, 2019
Table 5-3 shows transition of the CPU clock and examples of setting the SFR registers.
Table 5-3. CPU Clock Transition and SFR Register Setting Examples (1/3)
(1) CPU operating with high-speed on-chip oscillator clock (B) after reset release (A)
Status Transition
SFR Register Setting
(A)
(B)
SFR registers do not have to be set (default status after reset release).
(2) CPU operating with high-speed system clock (C) after reset release (A)
(The CPU operates with the high-speed on-chip oscillator clock immediately after a reset release (B).)
(Setting sequence of SFR registers)
Setting Flag of SFR Register
Status Transition
CMC Register
Note 1
OSTS
Register
CSC
Register
OSTC Register
CKC
Register
EXCLK OSCSEL AMPH
MSTOP
MCM0
(A)
(B)
(C)
(X1 clock: 1 MHz
f
X
10 MHz)
0 1 0
Note 2
0 Must
be
checked
1
(A)
(B)
(C)
(X1 clock: 10 MHz < f
X
20 MHz)
0 1 1
Note 2
0 Must be
checked
1
(A)
(B)
(C)
(external main clock)
1 1
Note 2
0
Must not be
checked
1
Notes 1.
The clock operation mode control register (CMC) can be written only once by an 8-bit memory
manipulation instruction after reset release.
2.
Set the oscillation stabilization time as follows.
Desired the oscillation stabilization time counter status register (OSTC) oscillation stabilization time
Oscillation stabilization time set by the oscillation stabilization time select register (OSTS)
Caution Set the clock after the supply voltage has reached the operable voltage of the clock to be set (see
CHAPTER 27 ELECTRICAL SPECIFICATIONS).
Remarks
1.
×: don’t care
2.
(A) to (H) in Table 5-3 correspond to (A) to (H) in Figure 5-14.