Nations Technologies Inc.
Tel
:
+86-755-86309900
:
Address: Nations Tower, #109 Baoshen Road, Hi-tech Park North.
Nanshan District, Shenzhen, 518057, P.R.China
63
/
631
Bit Field
Name
Description
100: Select system clock (SYSCLK) output
101: Select internal high-speed clock (HSI) output
110: Select external high-speed clock (HSE) output
111: Select PLL clock output
Notice: This clock output may be truncated when starting and switching the MCO
clock source.
When the system clock is output to the MCO pin, the output clock frequency should
not exceed 50MHz (the highest frequency of the I/O port).
23:22
USBPRES[1:0]
USB prescaler.
Set or cleared by software to generate a 48MHz USB clock. The values of these
bits must be valid before enabling the USB clock in the RCC_APB1PCLKEN
register.
00: Divide the PLL clock by 1.5 as the USB clock
01: The PLL clock is directly used as the USB clock
10: Divide the PLL clock by 2 as the USB clock
11: Divide the PLL clock by 3 as the USB clock
21:18
PLLMULFCT[3:0]
PLL multiplication factor (including bit 27)
Written by software to define PLL multiplication factor. These bits can only be
written when the PLL is disabled. The PLL output frequency must not exceed
108MHz.
00000: PLL input clock × 2
00001: PLL input clock × 3
00010: PLL input clock × 4
00011: PLL input clock × 5
00100: PLL input clock × 6
00101: PLL input clock × 7
00110: PLL input clock × 8
00111: PLL input clock × 9
01000: PLL input clock × 10
01001: PLL input clock × 11
01010: PLL input clock × 12
01011: PLL input clock × 13
01100: PLL input clock × 14
01101: PLL input clock × 15
01110: PLL input clock × 16
01111: PLL input clock × 16
10000: PLL input clock × 17
10001: PLL input clock × 18
10010: PLL input clock × 19
10011: PLL input clock × 20
10100: PLL input clock × 21