CPU BOARD ECOs
16 APR 2020

GNSS_5:
0 CUT TRACE " EXT RESET LINE TO GNSS - 5 "

COMMS:
0  CPU board output filtering on isolated side of level shifter, layout wrong
   VISO pin 14  ... pin 24 s/b on the output side of the filter
   see AdUM5412 data sheet page 26
   also voltage divider s/b on output side of filter

PAROSCI:
Do not install U1 "upside down"; we will not be using this IC

TS4100:
Remove D15
Remove R139
Add 1uF 0603 Caps in parallel with C159, C160, C156, C155

SUPERCAP:
Add 22awg wire from (F3,D17,C66, TP160)-pad to positive side of C49
  ( to reduce resistance )
Remove Q6
Remove Q5
Remove R135
Remove R134
Add blue wire connection: U31 pin 7 to D15 - Anode
  ( EXT_RESET_N )
Add 22 AWG wire from U31 pin 1 to positive junction of C159 and C160
  ( to reduce resistance )
Add 100uF, 100nF and 10nF Cap in parallel with C50
Add 100uF Cap in parallel with C200
R26 is now 909k 0603 1%
R28 is now 274k 0603 1%
R21 is now 237k 0603 1%
Add 0.1uF 0603 cap in parallel with R24

FREEWAVE:
Add 10k resistor between pin 1 and pin 2 on U52 ( Freewave Connector )
Cut trace between TP90 and gate of Q1 
Cut trace between R16 and OFF_BD_RESET_N via below it (in the direction of the SBD warrior footprint)
Bluewire gate to CPU GPIO connector J12, pin 13 ( CN1-21 )
   ( Pulling the line to ground is required to get the radio into programming mode for setup. )
Add blue wire between TP90 and TP93, restoring the "OFF_BD_RESET_N" net to the UARTs.

GNSS5-CLICK:
Swap A3 pins 13 and 14 ( Rx and Tx lines into GNSS-5-CLICK )
Remove the RESET pin on the GNSS5 board ( no need to Cut trace from A3 pin 2 )

CONSOLE RS232:
U39 is not installed:
   Add blue wire from CN2-93 to J25-2
     ( Same as blue wire U39 pin 9 to 11 )
   Add blue wire from CN2-95 to J25-3
     ( Same as blue wire U39 pin 7 to 6 )

VECTORNAV VN100:
Remove Q4

USB OTG: 
  remove R18
  remove U26 ( redundant to what is on the TS4100 )
  
---0---

FREEWAVE AND SBD WARRIOR:
We should add some mounting hole diameter changes to the motherboard for the freewave MM2 and the SBD warrior. It looks like all the holes are .125 which is too big for a 2-56. The plated diameter should be between .089 and .096.  We should also make these holes COUNTERSUNK FOR FLATHEAD SCREWS.

GNSS5-CLICK ASSEMBLY:
Cut pin 2 (the reset signal) off flush with the header. This eliminates the reset issue with the clock on the GPS receiver
Remove J1 (a 0 ohm resistor labeled USB Power on the silkscreen). This eliminates the possibility of powering the 3v3_ISO rail by plugging in the USB cable into the click.

SUPERCAP:
Beef up power 5V traces between supercap and TS4100.
  might consider changing pull-up resistors so they are pulled to 3v3_ts4100 instead of 3v3_iso
  move PDIS_VN100 from CN1_11 to another DIO ( CN1_49 ? )

VECTORNAV VN100:
Q4 can stay in once the DIO is rerouted. Maybe the right way forward is to cut the trace to Q4 and bluewire over to CN1_49?

POWER IN:
Use larger size fuses, at least 0805s; move them "east" away from connector