Hi I got a response from watterott germany, they tested the gps module with arduino board and mentioned there could be a power supply problem with the hydra board.
So I tried the following steps:
I soldered a RS232 listener at the gps board, so I can debug with the ublox software without or with the hydra board.
gps boad connected direct to the USB cliet SP red module (without hydra between) -> gps fix in <60 seconds
gps board connected direct to the USB client DP red module (without hydra between) -> gps fix in <60 seconds
gps board connected over hydra port (7) -> no gps fix, sattelites are not stable
I examinated the 3,3 V rail wizth a scope and got some noise on it. I tried to add some extra capacitors at the gps modul, but there is still noise on it. So I will order some inductors and filters to reduce the noise, otherwise the gps module is not working with hydra!
@ Skewworks - Sweet! I had not seen yours. I’ve been using a GPS library that somebody shared on the netduino forum. It mostly works, but throws an awful lot of exceptions while parsing sentences. It even has a flag to “ignore exceptions” Now that I know what the no fix issue is, I’ll definitely take a look at your code. Do you have a gadgeteer board yet? If not, I know somebody who got a great deal on a Cerberus recently (hah!), and would be willing to gift it and a GPS module for your coding efforts.
That would be awesome man! I’ve got a Hyrda but I’d love a Cerb w GPS. let me know if there’s anything I can kick back to you down the line. I got a good stockpile of hardware I used to prototype my software. And also software I could send your way
I wish i would have watched this thread sooner. played allot with GPS.
If your making a new module, check this one out.
I got it in and it works great and the size is just insane. http://www.sparkfun.com/products/10890
You can get one from SFE to try , but no more after that. you can get them from the manuf directly for $20 @ 50pcs.
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Thx for your replys, it took me a loot of time to test the gps module.
I yet have another sirf III gps receiver, so I will test it to.
I don’t like the power concept of the gadgeteer boards. All power is running over one thin flat cable line to the power module. Some extra power connectos would be fine to supply high power modules and other stuff. This also would avoid ground loops between the board and the modules…
@ MiRo, I have been a bit curious about that as well. Have you ever checked the voltage drop from the board to the module yet. I would be curious to see what that is.
it was abot 3,27V measured at the modul and 3,3 at client DP board. There is no differene if you power over USB or a well filtered external power supply. Over USB you see some more noise from the USB traffic.
When you press reset button on hydra board and hold it down you will get a gps fix with power over the hydra board. So the noise is produced by the ARM controller.
I first want to try my old SIRF III board, which was running on a Arduino without any problems. Hopefully I can do this tonight. Addition I will have a look at the SIRF IV controller, mentioned some mails before. The performance looks great, so maybe I will order one for testing and design my own board.
I can confirm that if I connect GPS module to FEZ hydra i can’t even get UTC time in RMC. But If I use regulated power supply and FTDI chip to read NMEA output, GPS gets fix in 2 minutes without any trouble inside of my house. This GPS module i’m using was replaced by my distributor UAM (CZE) and is confirmed to work with FEZ SPIDER as desired.
Gus, can you please confirm where is the problem ? Is it Hydra or GPS module ?
Try this, set Hydra next to the GPS module with FTDI connection. I want to see if it is interference from the processor that is causing GPS to not work nicely.
Next problem:
I tried a Fastrax UP500 gps antenna modul, as shown on the photo. The gps modul is working well with arduino board and working direct connected to RS232.
Same behavior with the hydra board:
Power over SP or DP modul (without hydra between) -> gps fix in <60s
Power over SP - hydra - gps modul -> no gps fix at same antenna position. I only used the 3,3V and GND line of hydra port 7
So no way to supply the seeed or fastrax gps modules over the 3,3V/ GND lines of the hydra board.
Next week I’m back in our emc office maybe we can measure radiation of of the hydra board with a spectrum analyzer in the emc chamber. So we can exclude radiated problems of the ARM. The 200 MHz core should have no influence at the gps modules. I still believe its the conducted noise at the power lines…
Can you post the direct link for the skiz.
I could be wrong, But i dont think its a cable/noise problem. I have ran used over 6 different GPS modules over a 4 wire phone cable that is 50’ long. Never had one issue.
If you feel its a power supply issue, you could cut the power wire on the cable and use another supply.
More info from the field… my GPS module (custom board, not Seeeds) works just fine on a Panda II. That is, it gets a fix in an expected amount of time from a cold start. It will be interesting to see what kind of filtering Seeed has done to make their module work with the Hydra and Cerbs.
I placed the hydra about 1.5 meters away from the seed gps module with one inductor in 3V3 power line and I got a 3D fix. SNR looks good, signal is stable.
@ GUS:
Hi Gus is it possible to change ARM core frequency by c# for testing?
Does anybody know where to order the 1.27 pitch flat cable connectors, because I’m running out of them?
Now that I know what the no fix issue is, I’ll definitely take a look at your code. Do you have a gadgeteer board yet? If not, I know somebody who got a great deal on a Cerberus recently (hah!), and would be willing to gift it and a GPS module for your coding efforts.