docs/library/machine.SPI: Add note about baudrate imprecision.
@@ -47,6 +47,10 @@ Methods
- ``pins`` - WiPy port doesn't ``sck``, ``mosi``, ``miso`` arguments, and instead allows to
specify them as a tuple of ``pins`` parameter.
+ In the case of hardware SPI the actual clock frequency may be lower than the
+ requested baudrate. This is dependant on the platform hardware. The actual
+ rate may be determined by printing the SPI object.
+
.. method:: SPI.deinit()
Turn off the SPI bus.
