[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Paparazzi-devel] Lisa/L Servos

From: Andreas Gaeb
Subject: Re: [Paparazzi-devel] Lisa/L Servos
Date: Mon, 22 Nov 2010 10:52:56 +0100
User-agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv: Gecko/20101027 Lightning/1.0b2 Thunderbird/3.1.6

Hi Poine,

Am 19.11.2010 14:48, schrieb antoine drouin:
> Hi Andreas
> You're correct, lisa/L is designed to drive 6 servos directly. All
> pins of the 64 pins STM32 are used. 
so the PPM input is not on the CON_SERVOS_2 connector, though it is
named RC_PPM on the schematic? What pin do you connect the receiver to?

> If you're not using some
> peripherals ( like I2C1, which is commonly used to talk to the I2C
> motor controllers on quadrotors) I could write code to use those pins
> to drive two more servos ( this is how I designed lisa/M, 6 servos and
> I2C1 or 8 servos ).
I'll probably need one I2C for sensors. Is I2C2 used by default?

> [...] Also you may not be able to supply them from the internal
> power supply of lisa/L ( there's one dedicated power supply for servos
> and USB but it's only good for 2 amps).
The servos will definitely need their own power, as even the motor BECs
cannot provide enough current for eight metal gear servos.

> The solution that I would advise in a big vehicle is to use a servo
> driver and a dedicated power supply ( BEC) located close to groups of
> servos.
I had already thought about using an Atmega or PIC based I2C to PWM
converter, there are some on the internet.

> The connection between the autopilot ( lisa/L) and the servo
> driver would be CAN which is a differential signal designed to travel
> long distances and be immune to electrical perturbations.
Do you know if CAN is better in this case than I2C?

> The CSC board (Can Servo Controller) could be used for that (
> )
is this what the sw/airborne/csc software and misc/csc hardware is
about? Is there any documentation on this?

> An even better solution would be to use a lisa/M (
> )
Is there already more information about this than on the Lisa wiki page?

> You could have for example one servo driver in each wing of your
> vehicle ( and maybe another one in the tail ). The electrical
> connection would be only two wires for CAN and two wires for power.
Ailerons, flaps and motor controllers are no more than 60 cm away. I
think I'll to drive these directly from Lisa and see about the jitter.
The tail is farther, so I'd rather put an extra controller there.

It does.

Thank you very much,

reply via email to

[Prev in Thread] Current Thread [Next in Thread]