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ST-LINK provides 8.08 MHz instead of 8.000 on new nucleo-H743ZI2.

Senior III

Seems there is an error in the STLink firmware (upgraded to the latest version just now), clock is off about 1%.


How exactly did you measure it?


Across C5, document:


Project: NUCLEO 144 H7 LEGACY

Variant: H743ZI

Revision: C - 01

Reference: MB1364

Size: A3

Date: 17-DEC-2018

Sheet: 9 of 9

Today it shows 8.04 MHz, that certainly is an indicator of clock misconfiguration in the STLINK, instead of clocking by 25 MHz stable crystal, frequency derived out of internal RC oscillator.

Bob S

I think @Community member​ means "what test equipment did you use to measure the frequency"? Like, how stable is the frequency reference inside your test equipment?

ST Employee

I'm reading 8.00XYZ MHz on Agilent 53181 right now.

Latest ST-LINK firmware V3J5M2.

I see what you mean, but the same measurement equipment (Hantek DSO4072C) shows correct value for nucleo-H743zi (old version, not upgraded for a year): 7.99998 MHz.

This is probably the cause, I'm using StLink upgade utility running out of Stm32CubeIDE on Linux, and it displays V3J4M2 as a latest, right at that moment. How to get V3J5M2?


If you’re using the HSI, the calibration value CubeMX uses is wrong. 0x20 instead of 0x40. It should be fixed In the next revision.

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Yes that might be the problem. More than the ST-LINK version.

For now, MCO on V3 is HSI/2 to keep 8MHz as for V2, but not for the best accuracy,