47 PTB0 - SCL0 (add header pin, label as SCL0)
48 PTB1 - SDA0 (add header pin, label as SDA0)
50 PTB16 - SDB (tied to all Chips, hardware shutdown)
65 * Comm - For bi-directional communication between halves
67 PTA1 - RX0 (Master Side)
68 PTA2 - TX0 (Master Side)
70 PTD2 - RX2 (UART Debug Header)
71 PTD3 - TX2 (UART Debug Header)
78 * SWD - (Main reflash header)
85 PTA5 (LED only for PCB, not Teensy)
89 PTD2 - RX2 (UART Debug Header, label as RX2)
90 PTD3 - TX2 (UART Debug Header, label as TX2)