ST STM32F446 Series User Manual

RM0390 Rev 4 131/1328
RM0390 Reset and clock control (RCC)
175
6.3.3 RCC clock configuration register (RCC_CFGR)
Address offset: 0x08
Reset value: 0x0000 0000
Access: 0  wait state  2, word, half-word and byte access
1 or 2 wait states inserted only if the access occurs during a clock source switch.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
MCO2[1:0] MCO2 PRE[2:0] MCO1 PRE[2:0] Res. MCO1 RTCPRE[4:0]
rw rw rw rw rw rw rw rw rw rw rw rw rw
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
PPRE2[2:0] PPRE1[2:0] Res. Res. HPRE[3:0] SWS[1:0] SW[1:0}
rw rw rw rw rw rw rw rw rw rw r r rw rw
Bits 31:30 MCO2[1:0]: Microcontroller clock output 2
Set and cleared by software. Clock source selection may generate glitches on MCO2. It is
highly recommended to configure these bits only after reset before enabling the external
oscillators and the PLLs.
00: System clock (SYSCLK) selected
01: PLLI2S clock selected
10: HSE oscillator clock selected
11: PLL clock selected
Bits 27:29 MCO2PRE: MCO2 prescaler
Set and cleared by software to configure the prescaler of the MCO2. Modification of this
prescaler may generate glitches on MCO2. It is highly recommended to change this
prescaler only after reset before enabling the external oscillators and the PLLs.
0xx: no division
100: division by 2
101: division by 3
110: division by 4
111: division by 5
Bits 24:26 MCO1PRE: MCO1 prescaler
Set and cleared by software to configure the prescaler of the MCO1. Modification of this
prescaler may generate glitches on MCO1. It is highly recommended to change this
prescaler only after reset before enabling the external oscillators and the PLL.
0xx: no division
100: division by 2
101: division by 3
110: division by 4
111: division by 5
Bit 23 Reserved, must be kept at reset value.
Bits 22:21 MCO1: Microcontroller clock output 1
Set and cleared by software. Clock source selection may generate glitches on MCO1. It is
highly recommended to configure these bits only after reset before enabling the external
oscillators and PLL.
00: HSI clock selected
01: LSE oscillator selected
10: HSE oscillator clock selected
11: PLL clock selected

ST STM32F446 Series Specifications

General

Brand	ST
Model	STM32F446 Series
Category	Microcontrollers
Language	English