Suggested changes for the R1 board

[jmlzone]

• 1) Fix the power and ground on the digital pots U103/U107.
  link to issue I1
  VDD = 17 = +5
  VSS = 7 = GND.

• 2) Fix the reversed B section of the digital pots.
  link to issue I6
  the A and B pins of section B of the digital pot, Pins 8 and 10 are reversed.
  pin 10 should be 'A' the high side
  Pin 8 should be 'B' the low side.

• 3) Move the DE9 connectors 3.7mm closer to the edge.
  link to issue I4

• 4) The link connections link to issue I3
  instead of going from a 6 pin connection to 7 pin connector, lets go to a 2x5 10 pin connector for the links.

outboard	pin	pin	inboard
link1C	1	2	3.3v through 2.2k
link1A	3	4	2.5v through 2.2k
GND	5	6	GND
link2A	7	8	2.5v through 2.2k
link2C	9	10	3.3v through 2.2k

the left edge and right edge connectors are mirrors of each other

• 5) I have been thinking about the ADC ref. I am considering a real 2.048v reference part. (just a though at this point)
  link to issue I2

• 6) add pull downs to keep off the PTT's and link outputs when initially powered
  link to issue I5
  Add 2.2k pull down resistors on the gates of Q201, Q401, Q105, Q105

• 7) Move RTC Connector in valuable front space to behind power supply does not need edge access.

• 8) Move Oled and pixel connector to where RTC was.

• 9) Move J311 currently inaccessible to behind power supply with a little space away from RTC

• 10) Consider a spot for SPI expansion? Voltage? # of unused CS?

• 11) Move the Oled and aux-io connections to I2C0 to I2C1. I2C0 is not longer accessible.