What signals can be used to drive the CLKIN0 input on Series 1 MCUs (EFR32/EFM32) devices on which it appears?
Some EFR32 and EFM32 Series 1 MCU devices support a CLKIN0 input to the CMU module, as depicted below - taken from Figure 10.1 "CMU Overview - High Frequency Portion" of the EFM32PG12 Reference Manual:
The purpose of the CLKIN0 input path is two-fold, depending on what is implemented on a particular MCU device. CLKIN0 supports a low-frequency (<= 1 MHz) square wave clock input which can be used:
For guidance on how to implement either of these configurations, see the following Knowledge Base articles:
In the EFR32BG22 datasheet, it writes that 1 MHz - 38 MHz External Clock from Input Pins (CLKIN0), but in your article, you said the CLKIN0 supports <1Mhz square wave. Which one is right?