[time-nuts] 5370B on eBay, carrier phase tracking GPS

[Christopher Hoover]

> Anyhow, these models only have the 4mb flash and can not be upgraded.

I've doubled the SRAM to 2Mb on one of the boards (P/N is 245-604090-153)
that I got off of ebay from isellreturns.

I haven't yet upgraded the flash.  The original board is mounted with AMD
NOR flash -- AM29LV400BB-70. I only have Intel flash parts on hand.  Hello,
Digikey?

If you've got the right gear and the right parts, it is all a SMOR(*).  :-)

I've yet to determine if the software can be upgraded, using the stock
updater and without copyright shenanigans.  This is a tangential interest
only for me.

The SRAM footprint is good for any standard 44-pin TSOPII SRAM of the right
geometry (x16) and speed (10ns).  I used an ISSI part (IS61LV12816L-10TL)
that I happened to have.

Any flash upgrade will require JTAG to blast the bits onto the new part, as
the bootloader obviously will be missing on it.  Fortunately pads for the
JTAG signals are on the bottom of the board.  (It might be possible to use
the GP4020's internal boot rom to do this, but I suspect that's more trouble
than JTAG, at least for me, and I want to get JTAG going anyhow.)

My goal is to do receiver development on the board.  The Zarlink chipset is
well documented and the processor core is ARM (which I know well and am
already set up for x-development).

BTW, there's a group working on an open source implementation for this
chipset:  http://gps.psas.pdx.edu/ 

-ch

(*) Small Matter of Rework