===== clock group =====

configuration of the used clocks.

<code>
    "clock": {
        "cpu": {
            "source" : "hse",
            "frequency" : "12 MHz",
        }
    }
</code>

==== source ====

defines the source of the clock signal. Supported clock sources are:
  * "hse"  (High speed external)
  * ...

**type**: enum

**default**: no default possible

==== frequency ====

defines the frequency that this clock has. 

**type**: string (Hz, kHz, MHz)

**default**: "1 MHz"