pub type HPRE_W<'a> = FieldWriter<'a, u32, CFGR_SPEC, u8, HPRE_A, 4, 4>;
Field HPRE writer - AHB prescaler
HPRE
SYSCLK not divided
SYSCLK divided by 2
SYSCLK divided by 4
SYSCLK divided by 8
SYSCLK divided by 16
SYSCLK divided by 64
SYSCLK divided by 128
SYSCLK divided by 256
SYSCLK divided by 512