ST STM32L0x3 Reference Manual page 189

RM0367
Bit 2 HSI16RDYF: Internal high-speed clock ready flag
This bit is set by hardware to indicate that the HSI 16 MHz oscillator is stable. After the
HSI16ON bit is cleared, HSI16RDY goes low after 6 HSI16 clock cycles.
0: HSI 16 MHz oscillator not ready
1: HSI 16 MHz oscillator ready
Bit 1 HSI16KERON: High-speed internal clock enable bit for some IP kernels
This bit is set and reset by software to force the HSI 16 MHz oscillator ON, even in Stop
mode, so that it can be quickly available as kernel clock for USARTs or I2C1. This bit has no
effect on the value of HSI16ON.
0: HSI 16 MHz oscillator not forced ON
1: HSI 16 MHz oscillator forced ON even in Stop mode
Bit 0 HSI16ON: 16 MHz high-speed internal clock enable
This bit is set and cleared by software. It cannot be cleared if the 16 MHz HSI is used directly
or indirectly as system clock.
0: HSI16 oscillator OFF
1: HSI16 oscillator ON
RM0367 Rev 7
Reset and clock control (RCC)
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