Hi Helge Walle,
we know at a long time period that the STM32 has much more noise
than the LPC2148.
The periphery on the LPC2148 works only with 8MHz the core with 60
Therefore we fly the wing aircraft only with the old Twog and
The Tiny13 is the best but has an old GPS module.
With the NARZE 32 (STM32103) i hat many problems wit the GPS I get
only a fix when i use a lage distance 40cm away from the autopilot
Try the following:
1. use ferrite rings for all wires from and to the autopilot PCB.
2. capsule the autopilot with aluminium film
3. keep the GPS module far away from the telemetrie antenna and the
4. If you use plan antenna keep a balsa wood plate covert with
aluminium film under the GPS module (after that we hat 3dB more).
5. Use a GPS module with active filter between the antenna an the
receiver. A club member make a new GPS module with the Neo8
and a filter an had often an error below 1m.
The last point use a lower periphery clock for the STM32. This take
a lot of work.
If you have 6 satellite revived (38dB and more) there is no problem
Please send me photos of you aircraft and the wireing.
Am 02.01.2017 18:17, schrieb Helge Walle:
Hello paparazzi community, and happy
Lately I have been trying to get a
satisfactory GPS reception with my STM32
based autopilots, but without success. The
two STM32 based boards I have, are a
Lisa/M v2.0 and one Elle0. In addition I
have an old Twog (LPC2148) to compare
with. I have three different GPS's from
different vendors, all Ublox5 or Ublox6.
The one used most for testing is an Ublox5
receiver with Sarantel antenna (bought
I am not sure if the reception quality is
influenced by me living 62 degrees north
When I connect my GPS receivers to either the
Twog or my PC, the fix happens very quickly,
and I get approx 6m accuracy outdoors. And,
most important, the results are consistent.
When I connect the same GPS's to the STM32
boards, the reception is noticeably worse, not
consistent, and it may take several minutes to
get a fix, even outdoors.
I tried longer leads, up to 1m. Reception got
better, but by far not as good as with the Twog or
a PC. Also I tried ferrite rings with better, but
not good results. Longer leads combined with
ferrite rings brought things close to ok. But then
again my plane is small...
I am planning on connecting the GPS via an optical
coupler, or even try a wireless connection to see if
the interference is reduced. This would anyway be
just for testing because of the added complexity. I
am not sure if the interference is carried through
the connection leads, or via air or both. Does
anyone know this?
Searching the net, I found a forum where it was
claimed that the interference has something to do with
cyclic reading of the STM32 flash. However I cannot
confirm this myself.
Shielding of the board is something I hesitate to try,
because it makes everything more difficult when
connecting and disconnecthing peripherals.
Before I continue with this, does anyone have any
knowledge that would help? There is a thread on the
mailing list from 2012, but I couldn't find anything very
Are there any settings on the STM32F1/4 that could be
helpful in reducing the noise?
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