allow user to supply different output voltage
The Silabs chip allows to generate clock outputs in different voltage domains, let's make this capability available to the user, at least via some jumpers so he can provide another external voltage reference.
- Status changed from New to In Progress
- % Done changed from 0 to 30
- have jumpers in-line of two of the four output banks of the PLL chipc
- jumper closed: reference is drawn from one (shared) "other voltage" LDO onboard
- jumper open: reference voltage can be provided/injected by user from external reference
What's still open to discuss is whether or not the LDO will be fixed (you have to change resistors to change the voltage) or adjustable. In the latter case, we'd apply the DAC output of the SAMD21 as an input to the tracking input of the LDO. However, this would mean that we'd no longer have the DAC output for driving a VCTCXO.