ADC Conversion time of STM32U5A5

[Shaheen]

Hello,

i've implemented a routine to measure some ADC channels with the MCU STM32U5A5ZJ.

After one measurement is finished (interrupt triggers after conversion) i start the conversion for the next channel.

Settings:

ADC conversion: Single conversion mode, conversion length: 1 (i just want one conversion per channel)

ADC CLK: 1843200Hz

Sample Time: 5 Cycles

14 bit mode: 17 Cycles

TCONV = (5 + 17) ADC clock cycles = 22 ADC clock cycles = 11,9us

 

To check the whole conversion time i toggled a pin at the start and end of conversion and looked at the signal on the oscilloscope.

My result is 50us for the conversion time.

My question is:

Why is the conversion time so long? I expected 11,9us and i got 50us!

 

I appreciate any help.

 

LG

Shaheen

 

 

[raptorhal2]

Edit: Perhaps interrupt processing time in HAL. Reading and saving a timer clock is probably more accurate.

 

[Shaheen]

The ADC CLK is derived from SYSCLK (SYSCLK  = 1843200Hz = 1,84Mhz) I used the multiplexer to select the clk source for the ADC. So the CLK frequency should be fine.

[Billy OWEN]

Hi @Shaheen 

 

This post has been escalated to the ST Online Support Team for additional assistance.  We'll contact you directly.

 

Regards,

Billy