Today, i try to understand the stm32 clock tree and i'm stucking at the adc clock. I would be very thankful for a small hint:
In the STM Specs is mentioned, that the ADC input clock must not exceed 14 MHz.
my mcuconf.h from the STM32 demo shows:
* HAL driver system settings.
#define STM32_SW STM32_SW_PLL
#define STM32_PLLSRC STM32_PLLSRC_HSE
#define STM32_PLLXTPRE STM32_PLLXTPRE_DIV1
#define STM32_PLLMUL_VALUE 9
#define STM32_HPRE STM32_HPRE_DIV1
#define STM32_PPRE1 STM32_PPRE1_DIV2
#define STM32_PPRE2 STM32_PPRE2_DIV2
#define STM32_ADCPRE STM32_ADCPRE_DIV4
#define STM32_MCO STM32_MCO_NOCLOCK
So the sytem clock after the AHB Prescaler is 72MHz and i calculated for ADC clock
72Mhz / 4 = 18 MHz
Am i making a mistake or is something wrong with STM32_ADCPRE of the mcuconf.h? OK, i use an 8MHz crystal witch seems to be the most common value.
best greetings from germany and thank you!
sorry for that. I can answer myself: forgotten the APB2 Prescaler.
The correct value is 72MHz / 2 /4 = 9MHz
No problems, that clock tree is quite complicated.
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