STM32F429I-DISC: ADC Sample rate out by factor of 3.7

[DetlefS]

Hi,

on STM32F429I-DISC the timer TIM2 kicks ADC1 and the data goes to buffer via DMA. APB1 clock for TIM2 is 36MHz, reload value for TIM2 is 143, I exspect 36e6/144= 250k samples/second.

I get 8.3e6 samples in 123 seconds which results in 67.4ks/s. This is factor 3.7 low, not even an integer ratio.

There is a clock issue for the 48MHz, see enclosed .ioc

 

What do I miss?

THX Cheers

Detlef

 

 

[TDK]

> I get 8.3e6 samples in 123 seconds which results in 67.4ks/s.

Measured how exactly? Be precise.

The timings provided in the Reference Manual are correct, so you need to present enough information to be able to spot the error.