This commit is between r8 and r9 and will be used as the basis for r10.
It includes some of the changes in r9 but predates the major changes to
the clock generator and IF transceiver ICs.
Additionally swap:
- EN_1V8, P6_10, U23 pin 100 (pull-down)
- !RX_AMP_PWR, P2_12, U23 pin 106 (pull-up)
Detecting which has the pull-up and which has the pull-down enables
version detection that may be more reliable than the ADC method.
