diff options
| author | Damien George <damien.p.george@gmail.com> | 2014-11-02 15:10:15 +0000 |
|---|---|---|
| committer | Damien George <damien.p.george@gmail.com> | 2014-11-02 15:10:15 +0000 |
| commit | 38bd762121486c908ae562086df93758de8be8b1 (patch) | |
| tree | bd26452b3a11b3951194bc03a31e53808bfd471f /docs/library/pyb.rst | |
| parent | 039887a0ac9bd02cfd84e4792d3d21a78bc06a7f (diff) | |
stmhal: Improve pyb.freq to allow 8 and 16MHz (not usable with USB).
Also restrict higher frequencies to have a VCO_OUT frequency below
432MHz, as specified in the datasheet.
Docs improved to list allowed frequencies, and explain about USB
stability.
Diffstat (limited to 'docs/library/pyb.rst')
| -rw-r--r-- | docs/library/pyb.rst | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/docs/library/pyb.rst b/docs/library/pyb.rst index d221e9720..8bb08215b 100644 --- a/docs/library/pyb.rst +++ b/docs/library/pyb.rst @@ -103,6 +103,18 @@ Power related functions supported and the largest supported frequency not greater than the given sys_freq will be selected. + Supported frequencies are (in MHz): 8, 16, 24, 30, 32, 36, 40, 42, 48, + 54, 56, 60, 64, 72, 84, 96, 108, 120, 144, 168. + + 8MHz uses the HSE (external crystal) directly and 16MHz uses the HSI + (internal oscillator) directly. The higher frequencies use the HSE to + drive the PLL (phase locked loop), and then use the output of the PLL. + + Note that if you change the frequency while the USB is enabled then + the USB may become unreliable. It is best to change the frequency + in boot.py, before the USB peripheral is started. Also note that + frequencies below 36MHz do not allow the USB to function correctly. + .. function:: wfi() Wait for an interrupt. |