Cmsemicon CMS32L051 - 4.6 Clock control

V1.2.2
CMS32L051 User Manual |Chapter 4 Clock Generation Circuit
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4.6 Clock control
4.6.1 Example of setting up a high-speed internal oscillator
The CPU/peripheral hardware clock (fCLK) must run at the high-speed internal oscillator clock after
a reset has been released. The frequency of the high-speed internal oscillator can be selected from
64MHz, 48MHz, 32MHz, 24MHz, 16MHz, 12MHz, 8MHz, 6MHz, 4MHz, 3MHz and 2MHz via 4 bits
FRQSEL0 to FRQSEL of the option byte (000C2H). In addition, the frequency can be changed via the
high-speed internal oscillator's frequency selection register (HOCODIV).
【Option byte setting】
Address: 000C2H
The options
7 6 5 4 3 2 1 0
byte
(000C2H)
FRQSEL4
FRQSEL3
FRQSEL2
FRQSEL1
FRQSEL0
The frequency of the high-speed
internal oscillator
f
HOCO
f
IH
0
1
0
0
0
64MHz
64MHz
0
0
0
0
0
48MHz
48MHz
0
1
0
0
1
64MHz
32MHz
0
0
0
0
1
48MHz
24MHz
0
1
0
1
0
64MHz
16MHz
0
0
0
1
0
48MHz
12MHz
0
1
0
1
1
64MHz
8MHz
0
0
0
1
1
48MHz
6MHz
0
1
1
0
0
64MHz
4MHz
0
0
1
0
0
48MHz
3MHz
0
1
1
0
1
64MHz
2MHz
Others
Setting is prohibited
1
1
1
FRQSEL4
0/1
FRQSANDL3
0/1
FRQSEL2
0/1
FRQSEL1
0/1
FRQSEL0
0/1