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Re: [Paparazzi-devel] lisa/m with mkk controller = problem


From: Felix Ruess
Subject: Re: [Paparazzi-devel] lisa/m with mkk controller = problem
Date: Mon, 7 Jan 2013 22:19:34 +0100

Feedback on this would be very much appreciated!
We really need your help, since the most active devs don't have an octo or any platform to test this...


On Sat, Dec 29, 2012 at 9:29 PM, Felix Ruess <address@hidden> wrote:
Hi,

Just a quick note:
In master you can now (again) override the default I2C bus speed by defining it in your firmware section, e.g. 200kHz for I2C1
<define name="I2C1_CLOCK_SPEED" value="200000"/>

Up to v4.2 the default for I2C1 is 200kHz, in master (v4.9-devel) it is 40kHz.
Christophe, any particular reason you made that the default with the new driver?
For motor controllers you don't want maximum speed, but usually just enough get get a command to every motor in every cycle...

We could of course also just not send the commands to all controllers in every cycle if necessary.

You also might want to increase the the transaction queue length if you use 8 motor controllers (default queue length is 8):
<define name="I2C_TRANSACTION_QUEUE_LEN" value="12"/>

Cheers, Felix


On Fri, Dec 28, 2012 at 6:12 PM, Prof. Dr.-Ing. Heinrich Warmers <address@hidden> wrote:
Hi
are you sure that there is not hardware problem on the  i2c bus?
In the diploma work from the HB-Autopilot i read:

"1.1.1    Störungen auf dem I²C Bus

Während der ersten Inbetriebnahme und Tests der Motoransteuerung viel ein stottern der Motoren auf. Während der Tests der Motorsteller war jedoch ein gleichmäßiger Lauf der Motoren festgestellt worden.

Die Überprüfung des Signalverlaufs am I²C Bus ergab, dass der Signalpegel nicht immer 0V erreichte sondern nur etwa 1V. Der Verdacht viel hierbei auf die ungewöhnlich niedrigen Pullupwiderstände, welche im Datenblatt für den  vorgeschlagen wurden. Es was durchaus möglich, dass die auf den Motorstellern verbauten ATMEGA8 Mikrocontroller nicht in der Lage waren den Signalpergel vollständig auf 0V zu ziehen.

Da bereits ein Prototyp des Pegelwandler mit eigentlich falsch bestückten PullUp Widerstanden einwandfrei funktionierte, wurde beschlossen die funktionierenden Werte von 3,3k Ohm zu übernehmen.

Nach Austausch der Widerstände waren keine Störungen mehr messbar, die Funktion somit einwandfrei".

On the HB Autopilot  3.3k Ohm for the i2c  pull up where used for correct working  with the mikrokopter  controlles.
On the lisa 2,2k Ohm are  used.

On the mikrokopter 1k an 100 Ohm series  resistors are used.
I had problems with the wires on the mikrokopter i2c bus.
Therefore is used 3 wires  twisted, one additional for gnd.
The gnd on the controllers where sometimes more than 300mV away from the gnd on the FC controller pcb.

Heinirch Warmers

 

 




Eduardo Lavratti schrieb:
Well, with i2c new driver the mkk driver work much better but the problem occur .
way the i2c1 clockspeed of newdriver is set to 40khz and i2c2 to 300khz ?


On Thu, Dec 27, 2012 at 12:19 PM, Eric BAHIER <address@hidden> wrote:
Hi,

It is not a I2C bus speed problem.

The problem is probably, (it was for me) we try to send to many byte on the I2Cbus, and the I2C bandwith is too small.

We must refresh the order to the MKK less time, you must reduce the quantity of data below the bandwith.

it is pssible, but I don't remenber the correct parameters in the airframe.xml file.... I will need it in few days...

Regards,

Eric




Le 27/12/2012 14:45, Eduardo Lavratti a écrit :
I think Its not buffer size ... its speed problem.
Anyone know if ppz i2c bus run at 100 or 400khz ?


On Thu, Dec 27, 2012 at 6:48 AM, Eric BAHIER <address@hidden> wrote:
Hi,

In the past with booz (and near futur), I fly an hexa.... I had the same problem.

The problem was an over load of the I2C bus, we put slower the data refresh for 6 mkk esc...

I dont rember where we make it slower....

Have nice day,

Eric


Le 27/12/2012 01:54, Eduardo Lavratti a écrit :
Hello,
anyone using 6 ou 8 MK esc with lisa/m ?

Today i put my lisa/m board on my BiG hexa.
This hexa fly very well with MK boards.
i have an mini octo that fly very well with mk boards too.

with lisa_m it fly some time and the lisa HANG resulting in crash.
in second test crashed again.

i make some tests in the bench.
i tested with big hexa setup and mini octo, all with i2c escs.

the result:
with 4 esc the lisa never hang.
With 6 esc  lisa hang after some time
with 8 esc lisa hang much faster than with 6.

i think it is a i2c buffer problem again.
I remember i configured the buffer last year an tell felix about this problem.

i will do more tests today.
regards.

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-- 
************************************
Lez Concept EURL

Eric BAHIER
15 chemin neuf
34 980 Montferrier sur LEZ
France

Tel : 33 4 67 59 92 53
Fax : 33 9 59 15 92 53
************************************
    

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