Developer

Servo problem with the new red (328) cards?

Hi.

Got my red ATMEGA328 ArduPilot from the latest Sparkfun batch a couple of days ago, and I am having problems getting the servos working.
First I tough the attiny45 was missing failsafe code, so I flashed v15 of the failsafe. No luck there, still no servo response. So I started scoping the in/out pins and I noticed that the servo control input pulses from the receiver are pulled down. Signals out from receiver is ok (3.5v), but the moment I connect them to Ardupilot inputs 1-4 they drop to 1v. CTRL input seems fine and has a 3.5v signal when connected and MUX and MODE status LED are triggered by remote. I have not looked at why the signal is pulled down yet and really don't feel like doing so either, since I bought the Ardupilot so I could start coding right away without designing the electronics first.

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Permalink Reply by Ulf on May 3, 2009 at 9:02am
hi all,

I'm not having RC-receiver connected.
I just hook up the power by Gnd/VCC as in the Fig. The servos get 5V and they move, but very strange (ticking a while instead of moving 45 degrees as in the code ran out of the box).
Or does the multiplexer does not work approriate without having something attached to CTRL/IN1/2/3?

Chris, by jumpering to BATT you mean putting a bit of solder on the BATT/SVRO pads and connect them?

Permalink Reply by David Low on May 3, 2009 at 9:11am
@Ulf: sorry for off-topic, but the way u plug in the sparkfun ftdi board is weird.
shouldn't it be like this?
http://diydrones.com/profiles/blogs/how-to-connect-a-sparkfun-ftdi
Permalink Reply by Ulf on May 3, 2009 at 9:27am
Ups..sorry, of course. just plugged it quickly in for the image, so thats not the issue.

3D RoboticsPermalink Reply by Chris Anderson on May 3, 2009 at 9:58am
That is a kind of weird setup.

If you're going to use the BATT pins, you need to unsolder the SVRO side of solder bridge on PSEL and instead solder it on the BATT side.

But why would you want to do that if you're going to use it with RC equipment? And why not just test this with RC equipment as it was designed? I'm confused why you're making it so complicated by deviating from the instructions.

DeveloperPermalink Reply by John Arne Birkeland on May 3, 2009 at 12:14pm
I could be wrong, but I think the current failsafe design require an active signal on CTRL for the servo output to work.

AdminPermalink Reply by Thomas J Coyle III on May 3, 2009 at 1:06pm
Chris,

John Birkeland is correct about the two upper left hand pins being attached to the servo rails as I tried it myself and observed the correct led pattern for a factory fresh board.

I know that you stated a while back that the power pins in the upper left hand corner were not connected to the processor, but this does not seem to be the case with the blue boards.

Therefore, Ulf has a problem with his board as powering the board from either the upper left hand corner pins or the servo pins should result in the correct led pattern for a factory fresh board.

Also, looking at the way that Ulf has his servo hooked up to the servo out pins, it looks like the servo connector is reversed as the black wire (gnd) appears to be inboard and not outboard as it should be if plugged in correctly.

Regards,
TCIII
Permalink Reply by Reto on May 3, 2009 at 1:49pm
I agree with Thomas. Servo seems connected as wrong as FTDI.

3D RoboticsPermalink Reply by Chris Anderson on May 3, 2009 at 2:33pm
Tom, you're right on both counts. I actually said that the power pins in the FTDI row (that's BLK and the VCC two pins above it) are not connected to the processor. The VCC and GND at the top are connected, as you observed, but we don't recommend you use them because we're reserving them for the expansion board.

Well spotted that he has his servos plugged in backwards. You wouldn't believe how often we see this. Even though it's plainly marked on the board, it's the number one cause of tech support problems. I'm sure this is true across the RC world, thanks to the no-polarity of RC connectors, but it's stunning to see it here, where we have pretty sophisticated users.
Permalink Reply by Ulf on May 3, 2009 at 3:01pm
Hi,
i guess i was a bit too quick with my foto demo. now i got a video:
Video
(The Video is mirrored)
running the 2.1-code out of the box.
Can anyone reproduce this? Is this normal?
I'm still waiting on the remote and i wanted just test the board if it's working well. i thought it should work using this setup from scratch, I tested the servorail to vcc and gnd and it is connected.

3D RoboticsPermalink Reply by Chris Anderson on May 3, 2009 at 3:24pm
Ulf, I don't see anything out of the norm. Please just wait until you have the standard setup and check back with us then. So far your unwillingness to do things as recommend and your photo errors have just wasted people's time.

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