Datasheet

Table Of Contents
DS13105 Rev 4 35/135
STM32WLE5J8/JB/JC Functional overview
46
The RTC clock is derived (selected by software) from one of the following sources:
LSE clock
LSI clock
HSE32 clock divided by 32
The functionality in Stop mode (including wakeup) is supported only when the clock is
LSI or LSE.
The IWDG clock is always the LSI clock.
The RCC feeds the CPU system timer (SysTick) external clock with the AHB clock (HCLK1)
divided by eight. The SysTick can work either with this clock or directly with the CPU clock
(HCLK1), configurable in the SysTick control and status register.
FCLK1 acts as CPU free-running clock. For more details, refer to the programming manual
STM32 Cortex
®
-M4 MCUs and MPUs programming manual (PM0214).
Figure 7. Clock tree
1. For full details about the internal and external clock source characteristics, refer to the electrical characteristics section in
the device datasheet.
2. The ADC clock can additionally be derived from the AHB clock of the ADC bus interface, divided by a programmable factor
(1, 2 or 4). When the programmable factor is 1, the AHB prescaler must be equal to 1.
MSv62605V2
LSI RCC 32 kHz
LSE OSC
32.768 kHz
LSCO
to IWDG
OSC_IN
OSC_OUT
MCO
/1 - 16
/32
LSE CSS
PLL
/P
/R
/Q
/M
SYSCLK
MSI
MSI
HSI16
HSI16
HSE32
HSE32
PLLRCLK
PLLRCLK
LSE
LSI
SYS clock
source
control
SYSCLK
MSI
HSI16
AHB3
SHDHPRE
/1,2,...,512
HCLK1
HCLK3
APB1
PPRE1
/1,2,4,8,16
to CPU, AHB1, AHB2
to CPU FCLK
/8
to CPU system timer
APB2
PPRE2
/1,2,4,8,16
PCLK1
PCLK2
to AHB3, Flash, SRAM1, SRAM2
to APB1 TIMx
to APB2 TIMx
to USART1 to LPTIM1
to LPUART1
to ADC
to RTC
x1 or
x2
x1 or
x2
to I2C1
PCLKn
SYSCLK
HSI16
HSI16
HSI16
PCLKn
LSI
LSE
PLLPCLK
SYSCLK
PCLKn
LSE
to APB2
to APB1
to RF
SYSCLK
MSI
to RNG
PLLQCLK
PLLRCLK
OSC32_IN
OSC32_OUT
LSI
LSE
LSI
LSE
HSEPRE
/1,2
x
N
to I2C2
to I2C3
to LPTIM3
to LPTIM2
PCLK3 to APB3
to USART2
HSI16
to SPI2S2
I2S_CKIN
HSI16
PLLPCLK
PLLQCLK
CPU
HPRE
/1,2,...,512
HSE32 OSC
32 MHz
HSE CSS
MSI RC
100 kHz - 48 MHz
HSI16 RC
16 MHz
LSI DAC