Rainbow Electronics NUC120 - Manual (Page 30)

NUC120 Series DATA SHEET
5.3.2 System Clock & SysTick Clock
The system clock has 5 clock sources which were generated from clock generator block. The clock
source switch depends on the register HCLK_S(CLKSEL0[2:0]). The block diagram lists below.
011
010
001
000
1xx
10K
PLLFOUT
32K
12M
22M
HCLK_S(CLKSEL0[2:0])
CPU in Power Down Mode
1/(HCLK_N+1)
HCLK_N(CLKDIV[3:0])
HCLK
CPUCLK
PCLK
CPU
AHB
APB
Figure 5-3 System Clock Block Diagram
The SysTick clock(STCLK) has 5 clock sources which were generated from clock generator block.
The clock source switch depends on the setting of the register STCLK_S(CLKSEL0[5:3]. The block
diagram lists below.
STCLK
011
010
001
000
1xx
HCLK
12M
32K
12M
22M
STCLK_S(CLKSEL0[5:3])
1/2
1/2
1/2
Figure 5-4 SysTick clock Control Block Diagram
Publication Release Date: May 31, 2010
- 30 - Revision V1.02