Link Module with bigger FPGA (1000) - 7150SV(?) - low speed downlink

For low speed downlink with built in IOP functionality 

rev register should read 5730 (hex)

This version for low speed down link for 7150 systems is built from
the high speed version 5630 and incorportates all the changes for that case

Notes below are extracted from high speed link module rev 5630 and can
be regarded more as a change history as none of the intermediate releases
for the high speed case were built for the low speed case

Incorporate changes to allow for variable format for NMEA - $PASHR motion data

below are notes from rev 5610

1) swap IO2 and IO3 - i.e. pins for trigger in and trigger out are swapped
2) incorporate trigger in led - toggles with each trigger in
3) correct pps edge selection to conform to IOP Dry
4) add edge selection for trigger in


Below are notes from rev 5600 - note position of trigger in trigger out

This version is an upgrade of High Speed Link Module (3220)

It incorporates the following IOP functionality
The signal names in the schematic are indicated and 
are the same as for the 7101/8125H series for Thor box
   
   1) pps - IO1RX
   2) trigger in - IO2RX
   3) motion sensor data (4 formats) - RXUART1
   4) trigger out - IO3TX