Choosing Internal vs external Clock

[DJMicro]

I do a project with the newer STM32 G , C series and i am curious what are the benefits of external clock vs using the internal clock, because it will save cost and layout space ?

[Andrew Neil]

Internal RC clocks typically don't have the accuracy & stability of an external crystal or other clock source.

So check the datasheet carefully; if the specs meet your requirements, then the internal oscillators will be fine - if they don't, you'll need something else.

This is particularly important for things like UART - especially at higher baud rates.

[TDK]

An HSE-based clock will be more accurate. Often needed for things like USB.

Apart from that, it's mostly downsides. More components, more power, potential for interference or bad layout.

Unless you need it for something, I'd stick with the HSI clock.