pub type CKSEL_W<'a, const O: u8> = BitWriter<'a, u32, CFGR_SPEC, CKSEL_A, O>;
Field CKSEL writer - Clock selector
CKSEL
LPTIM is clocked by internal clock source (APB clock or any of the embedded oscillators)
LPTIM is clocked by an external clock source through the LPTIM external Input1