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Re: [Paparazzi-devel] PaparazziUAV project - control more servos

From: hendrixgr .
Subject: Re: [Paparazzi-devel] PaparazziUAV project - control more servos
Date: Thu, 3 Nov 2016 07:27:51 +0200

I have the software ready and tested for the PCA9685 if you need it.

On Sat, Oct 29, 2016 at 3:52 PM, Prof. Dr.-Ing. Heinrich Warmers <address@hidden> wrote:
i think there are many  ways to a solution:

1 Cascade the 5-stage Johnson 4017b counter as described in the data sheet page 8  HEF4017B MSI 5-stage Johnson counter. You need a additional and gate like
   the   4081. This chip  has  four. (look  here aso
   This solution may cause wrong pulses for one period of 40ms.
   Conneting the reset of the secound 4017b to the reset input of the first on the paparazzi autopilot  may solve this problem.
   You can also use a second free pin of the autopilot like the twog to reset the second counter.
   An disadvantage of the cascade solution is a  doubled time period to 40 ms. This may cause problems with the  servos.

2 Use a additional counter to separate pins (reset, Impulse). With this solution you can generate a standard rate of 20 ms for all servos outputs.

3 For STM32 autopilots use 2 normal servo outputs for 2 4017 counters

4 Use the PCA 9685 with 16 outputs like this pcb .
   You can cascade the pca9685 to get 32 outputs. This soulution will work with all paparazzi autopilots.

All this solutions need software changes. This may need same time to learn  the paparazzi software structures.



Am 10.10.2016 08:28, schrieb Ivan Fedorov:

  My name is Ivan, I have an interest in  buinding RC
  planes,  especially EDF jets.   On this type of jets I typically have many control surfaces
  you need to manage plus I need to manage thrust vectoring as
  So typically I have many servos to manage (10+) with a
  custom mixes from typical three control inputs (ailerons,
  elevator, rudder).       
  My intention is to build an on-board mixer which can take
  these inputs from a receiver and  generate a feed for
  multiple servos.   
  I have been researcing what kind of hardware I can use for
  that and your Lisa/S looks fantastic - small, lightweight
  and expandable in case
  I want to put more functions on it.   

  However it only has a limited number of servos that it can

  I wonder if it can be extended to control more servos using
  an idea descrbed here

  I would presume if I  take four of Lisa's output pins
  to manage 2*4017 chips and add a relative small piece of
  code to the PaparazziUAV project to control these pins
  accordingly then Lisa could manage up to 20 servos.

  Could you kindly have a look to the URL above and assess the
  Is that doable or there would be issues?
  Where custom mixes can be configured?
Could you please suggest what code blocks need to be written?

I could try to develop them then and with your guidance add
  to your project.   
  Hope to hear from you soon.

  Thank you and best regads,   Ivan

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