MK22 pin & func:	connected to:
1	PTE0		C6000 pin 39
2	PTE1		C6000 pin 47
5	PTE4		1M flash W25Q80BV pin 5 DI IO-0
6	PTE5		1M flash W25Q80BV pin 6 CLK
7	PTE6		1M flash W25Q80BV pin 7 DO IO-1
10	USB0 DP+	3.5mm socket 'tip'
11	USB0 DM-	2.5mm socket 'ring'
31	I2C0 SCL	to AT24C512 EEPROM pin 6 SCL & AT1846S pin 2 SCLK
32	12C0 SDA	to AT24C512 EEPROM pin 5 SDA & AT1846S pin 3 SDIO 
34	PTA0		SWD CLK
35	PTA1		PTT button
36	PTA2		Top orange button
37	PTA14		SWD DIO
42	PTA12		C6000 pin 34
44	PTA14		C6000 pin 36
45	PTA15		C6000 pin 35
46	PTA16		C6000 pin 37
51	PTA19		1M flash W25Q80BV pin 1 /CS
54	PTB1		Small black button below PTT
57	PTB9		Small blue button
58	PTB10		C6000 pin 44
59	PTB11		C6000 pin 43
62	PTB16		C6000 pin 41
63	PTB17		C6000 pin 42
64	PTB18		Green LED
65	PTB19		Front panel ribbon pin 20
66	PTB20		Front panel ribbon pin 19
67	PTB21		Front panel ribbon pin 18
68	PTB22		Front panel ribbon pin 17
69	PTB23		Front panel ribbon pin 16
70	PTC0		Front panel ribbon pin 15
71	PTC1		Front panel ribbon pin 14
72	PTC2		Front panel ribbon pin 13
73	PTC3		Front panel ribbon pin 12
76	PTC4		Front panel ribbon pin 3
79	PTC7		C6000 pin 51
80	PTC8		Front panel ribbon pin 9
81	PTC9		Front panel ribbon pin 8
82	PTC10		Front panel ribbon pin 7
83	PTC11		Front panel ribbon pin 6
84	PTC12		Front panel ribbon pin 5
86	PTC14		Red LED
90	PTC16		C6000 pin 50
91	PTC17		C6000 pin 49
92	PTC18		C6000 pin 48
93	PTD0		C6000 pin 58
94	PTD1		C6000 pin 57
95	PTD2		C6000 pin 56
96	PTD3		C6000 pin 55

EEPROM AT24C512 & radio IC AT1846S I2C connections are on a common bus

Have nominally called pin 1 of the front panel ribbon connector on the main PCB
closest to the side where PTT is located.  Pin 20 closest the side where the external
speaker mic sockets are.