These pages describe the Axiom Sandpiper II GPS module. The manufacturer went out of business some time between 2000 and 2006, but many of these are still available cheaply in 2006 via eBay and from electronics surplus stores. They seem to be popular with radio hams.
This is a SiRF device based on the original SiRFstar I. However,
it doesn't come up in SiRF binary, nor have we ever seen it
respond to the $PSRF that gpsd uses as a SiRF probe,
despite the manual's insistence that it should. Apparently this
problem is not unique to the Sandpiper but general
in SiRFStar 1 devices.
The material in these pages (other than this one) was extracted from descriptive materials supporting an eBay auction. Material specific to the auction has been removed, leaving the technical content, vendor spec sheets, and manuals in place.
These materials describe the bare OEM module. An anonymous note referenced from the web page tells us the basics of interfacing to it. It has two rows of pins, the pin with the square pad is pin 1. The pins are numered as follows:
The module is already RS-232 ready, no need for a level-converter chip (MAX-232). For a serial connection to your PC all you need to do is apply power(+5vdc) and wire TX,RX, and ground to your PC. Once powered up the receiver will output NMEA at 4800,8,n,1. If you want to you can add a battery backup (3.6vdc); there is a pin for this. This will allow the receiver to lock onto a signal within 10 seconds. On first power up don't expect a lock for about 90 to 120 seconds.
You may find your unit is enclosed in a black plastic case with a DB9 on a cable coming out of it and two connectors on it. If so,
| 1 | PPS |
| 2 | RX |
| 3 | TX |
| 4 | open |
| 5 | ground |
| 6 | open |
| 7 | open |
| 8 | open |
| 9 | open |
Neither the bare board nor the cased unit comes with a power supply. Fortunately, the board is electrically compatible with the 5-volt wall warts used on many routers and USB hubs. You may have problems matching the barrel connector on the cased unit, however.
The model MS15-050250-1AD (5 VDC, 2.5A) power supply used with some Linksys blue boxes, including version 1 of the popular WRT54G, seems to do nicely. ESR has been using one with no problems; he reports that he checked it with a VOM and it does indeed produce regulated power.
Beware: newer Linkys blue boxes use a 12VDC power supply with the same barrel connector. If you plug one of there into a Sandpiper you might very well burn it up!