STM32F0 datasheet(15/71 Pages) STMICROELECTRONICS

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Peripheral migration

In addition to the differences described in the table above, the following additional

adaptation steps may be needed for the migration.

System clock configuration: when moving from STM32F1 series to STM32F0 series,

only a few settings need to be updated in the system clock configuration code; mainly

the Flash settings (configure the right wait states for the system frequency, prefetch

enable/disable) or/and the PLL parameters configuration:

In case HSE or HSI is used directly as the system clock source, only the Flash

parameters should be modified.

In case PLL (clocked by HSE or HSI) is used as the system clock source, the

Flash parameters and PLL configuration need to be updated.

Table 10 below provides an example of porting a system clock configuration from STM32F1

to STM32F0 series:

–

STM32F100x value line running at maximum performance: system clock at

24 MHz (PLL, clocked by the HSE (8 MHz), used as the system clock source),

Flash with 0 wait states and Flash prefetch queue enabled.

–

STM32F0 series running at maximum performance: system clock at 48 MHz (PLL,

clocked by the HSE (8 MHz), used as the system clock source), Flash with 1 wait

state and Flash prefetch enabled.

As shown in Table 10, only the Flash settings and PLL parameters (code in Bold Italic)

need to be rewritten to run on STM32F0 series. However, HSE, AHB prescaler and the

system clock source configuration are left unchanged, and APB prescalers are adapted to

the maximum APB frequency in the STM32F0 series.

Note:

The source code presented in Table 10 is intentionally simplified (timeout in wait loop

removed) and is based on the assumption that the RCC and Flash registers are at their

reset values.

For STM32F0xx, you can use the clock configuration tool,

STM32F0xx_Clock_Configuration.xls, to generate a customized system_stm32f0xx.c file

MCO clock source

– MCO pin (PA8)

– Connectivity Line: HSI, HSE, PLL/2,

SYSCLK, PLL2, PLL3 or XT1

– Other product lines: HSI, HSE, PLL/2 or

SYSCLK

MCO(PA8): SYSCLK, HSI, HSE, HSI14,

HSI48, PLLCLK/2, LSE, LSI(1)

Int. oscillator

measurement /

calibration

LSI connected to TIM5 CH4 IC: can measure

LSI w/ respect to HSI/HSE clock

– LSE and LSI clock are indirectly measured

through MCO by the timer TIM14 with

respect to HSI/HSE clock.(1)

– HSI14/HSE are indirectly measured

through MCO by means of the TIM14

channel 1 input capture with respect to HSI

clock.(1)

– HSI48 can be calibrated on the run by the

mean of the CRS using a reference

clock.(1)

1. Same feature but spec change or enhancement.

Table 9. RCC differences between STM32F1 and STM32F0 series (continued)

RCC

STM32F1 series

STM32F0 series

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