connecting an XTAL with an STM32L412

[deep_rune]

I want to connect an (HSE) crystal with an STM32L412 - I see from the cubeIDE ports that PA0 is the CK_IN, but I've always used xtals with two ends - where does the other end of the xtal connect to? Ground?

[Tesla DeLorean]

Need to use an oscillator, like a TCXO, or existing clock source in your system

[deep_rune]

sorry i don't understand... i just want to use an external crystal to time my chip, how can i do this? do i need to use the RCC osc pins? Im not sure

[Tesla DeLorean]

You have to make the crystal oscillate externally, you could use a pair of inverters if you insist on doing it from scratch​

[deep_rune]

?? im really confused - I can't connect a crystal like I can with other chips? Ive used atmega chips and you just connect the crystal between two pins, and i was using an STM32F031K6 with a crystal connected..

[TDK]

On most STM32 chips, there are two pins for the HSE. On some reduced pin count chips, such as this one, there is only one pin assigned to HSE. Thus, you cannot use a crystal in the same way as other chips. It can only operate in "HSE Bypass" mode.