No fix on u-blox neo 6m

External hardware connected to the STM32 board
stevestrong
Posts: 2044
Joined: Mon Oct 19, 2015 12:06 am
Location: Munich, Germany
Contact:

Re: No fix on u-blox neo 6m

Post by stevestrong » Wed Nov 02, 2016 3:36 pm

Yes, it is possible to change the online 3.3V regulator, just pick up one with the same pinout but at least 200mA.

User avatar
mrburnette
Posts: 2190
Joined: Mon Apr 27, 2015 12:50 pm
Location: Greater Atlanta
Contact:

Re: No fix on u-blox neo 6m

Post by mrburnette » Thu Nov 03, 2016 2:15 am

1. GPS knows the current date and time (so it has a signal)
2. GPS is showing multiple satellites (so it has multiple signals)
3. GPS doesn't know where it is (satellites have no relative position info, and the other position fields are empty)
4. GPS doesn't have a lock (see #3)
5. GPS doesn't have many satellites with strong (greater than 25dB) signals
3, 4, 5:

On Neo-6 units I have purchased from China, the worst-case time to work through the "where am I" logic has been a few minutes over 10 hours! This has been repeated 5 times with new units, so do not give up. It all depends on signal strength, sats in view, and many other little issues.

After the first full sync, power-on to lock is under 30 seconds consistently.
Ray

jucordero
Posts: 7
Joined: Sun Oct 16, 2016 8:47 pm

Re: No fix on u-blox neo 6m

Post by jucordero » Fri Nov 04, 2016 2:20 am

The true mystery is the fact that the receiver does fix its position within a reasonable TTFF (30 seconds) placing it on the same breadboard with a different MCU. Again, it doesn't seem to be a signal strength issue or sky view, unless the Signal to Noise has any dependence on the internals of the device.

zmemw16
Posts: 1674
Joined: Wed Jul 08, 2015 2:09 pm
Location: St Annes, Lancs,UK

Re: No fix on u-blox neo 6m

Post by zmemw16 » Fri Nov 04, 2016 3:03 am

same cpu e.g. both blue pill or blue pill v maple mini
or maybe avr v stm32 e.g. 16MHz / 72MHz
capacitor quality & quantity?
srp

User avatar
ahull
Posts: 1718
Joined: Mon Apr 27, 2015 11:04 pm
Location: Sunny Scotland
Contact:

Re: No fix on u-blox neo 6m

Post by ahull » Fri Nov 04, 2016 11:20 am

jucordero wrote:The true mystery is the fact that the receiver does fix its position within a reasonable TTFF (30 seconds) placing it on the same breadboard with a different MCU. Again, it doesn't seem to be a signal strength issue or sky view, unless the Signal to Noise has any dependence on the internals of the device.
Try screening the maple mini board with foil (don't short it out obviously). Could be RF interference.
- Andy Hull -

User avatar
Pito
Posts: 1729
Joined: Sat Mar 26, 2016 3:26 pm
Location: Rapa Nui

Re: No fix on u-blox neo 6m

Post by Pito » Fri Nov 04, 2016 12:30 pm

Try to pass all three wires (gnd, vcc, data) via a ferrite bead/toroide (2-3 windings through the toroid for example).
GPS ---> ferrite ----> Maple
filter.JPG
filter.JPG (10.51 KiB) Viewed 782 times
Pukao Hats Cleaning Services Ltd.

User avatar
mrburnette
Posts: 2190
Joined: Mon Apr 27, 2015 12:50 pm
Location: Greater Atlanta
Contact:

Re: No fix on u-blox neo 6m

Post by mrburnette » Fri Nov 04, 2016 12:52 pm

zmemw16 wrote:same cpu e.g. both blue pill or blue pill v maple mini
or maybe avr v stm32 e.g. 16MHz / 72MHz
capacitor quality & quantity?
srp

When I was prototyping Tardis Time last Fall, I had to use a mu-metal shield to separate the uC from the GPS patch antenna because the RF hash overloaded the GPS frontend. In the final project, I used a coffee can with the ESP8266 on the bottom and the GPS on the top.

Ray

ilf
Posts: 8
Joined: Thu Jun 08, 2017 7:40 pm

Re: No fix on u-blox neo 6m

Post by ilf » Fri Jun 09, 2017 3:58 pm

Did someone manage to make it work. I have the same problem, I will try to scientifically test tomorrow, because all my receivers work either with the Arduino Pro Mini or directly connected with USB to serial with the u-center (even through wine on linux). I also used couple of decoupling capacitors on the GPS and still a no-go (Both with external LDO and with the build in, no difference).

Tried with NeoGPS/TinyGPS++ libs, so if someone has any ideas I'm all ears. Thanks

ilf
Posts: 8
Joined: Thu Jun 08, 2017 7:40 pm

Re: No fix on u-blox neo 6m

Post by ilf » Sat Jun 10, 2017 9:10 pm

Hi,

I want to report back and seek some advice. It seems that if I connect the GPS directly to a power source on the breadboard everything is fine. Nothing else on the breadboard is powered (I have an SPI device, the Blue Pill and I2C device /10DOF-IMU/). Once I connect the GND to the GND of the Blue Pill, the GPS stops working correctly. Again, nothing else is connected, nor is the Blue Pill powered, just attaching the GND to the GND of the breadboard (where the GPS is already connected).

I disconnected the GND from the Blue Pill and attached the RX/TX wires from the GPS to the Blue Pill. Again, nothing else is connected or powered (except the GPS), This also messes up the GPS but also causes the Power LED of the Blue Pill to start blinking in sync with the LED of the GPS. I'm a bit lost here. I don't have an oscilloscope around, just a very cheap multi-meter. Any ideas guys? Seems like either something is shorted on the Blue Pill (it is the same with my whole batch, I have 5 of them) or it is some grounding/decoupling issue.

Any help will be greatly appreciated.

User avatar
ahull
Posts: 1718
Joined: Mon Apr 27, 2015 11:04 pm
Location: Sunny Scotland
Contact:

Re: No fix on u-blox neo 6m

Post by ahull » Sat Jun 10, 2017 10:14 pm

It could simply be picking up so much noise (unfiltered mains hum, or other environmental RF for example) from the room, due to the long ground wires acting as an antenna, that it swamps out the signals. Are there RF screening cans surrounding the high frequency GPS components, if so are they grounded or are the components simply on a bare board?

Show us some pictures of your exact setup. The blinking in time to the LED suggests a poor connection somewhere, or your power supply is sagging under load.

You may need to fabricate some "tin hats" for some of the elements of the system to keep the mischievous RF pixies from getting into, or indeed out, of things they shouldn't. You may be able to fabricate something using tin snips or stout scissors, and a few thin steel "tin cans", or even just hide the sensitive bits under some earthed single sided PCB material. A more professional finish would require some tin or brass sheet. Easily obtainable from all the usual ebay suspects. Small brass sheet offcuts would to the trick and are pretty cheap. For example -> http://stores.ebay.co.uk/SGS-Metals/Cle ... 34.c0.m322
- Andy Hull -

Post Reply