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Using Vin pin

(15 posts) (5 voices)

Started 3 years ago by PsyKo
Latest reply from xpomvid

PsyKo
Member

Hello,

I'm actually trying to do a quadcopter based on a maple board.
While I was setting up everything (motor control, and so on), I was using maple powered over the USB. It was more convenient to upload and stufs... My 4 motor were running well, according to my commands.

Now I want to get rid of the wire. I use the 5v supply coming from my battery through the motor regulator. (In RC Plane, motor controller (known as ESC) provide a 5v voltage to the RC receiver.) So I simply plugged one of the 5V output of my ESC to the vin of the mapple and switched the jumper to EXT power supply.
I also use an Xbee module as Serial replacement (not for upload). The xbee module works well.

For some reason, when using Vin, my motors are not responding. Most likely only one of them start. It's not related to the motor, because if I switch back to USB power, they all run well. I don't have the quadcopter here for now, but it's only one pin that works.
My motors are connected to PWM pin 8,11,12 and 14 if I remember correctly.

Do you have any idea of what's going on ?

Is there a particular setup for using Vin to power the Maple ??

To be honest, I don't...

Thanks a lot

Posted 3 years ago #
gbulmer
Moderator

Have you got access to any test equipment, e.g. an oscilloscope, to look at the signals?

Have you access to a volt-meter/multi-meter to check the input voltage to the Maple?

If you have test equipment, disconnect the motors, run the software, measure the voltages, then connect one motor at a time, measure and repeat.

If you haven't any test equipment it will be much harder to debug. You might try putting a resistor and LED onto each Maple pin connected to each motor. If you are lucky, you might see something dim or flicker.

Posted 3 years ago #
BJ Freeman
Member

base on the schematic for R5, the Vin through the Jack or JP1 is 7-18 volts and has a diode in series which drops it another 0.7volts. this feeds the 3.3 volt regulators. So it should work.
however you 5volt might drop below 4.3v. the would give 3.6 to the 3.3 regulators. if you 5Volt drops below 4.3volts VIN then the 3.3 regulators may not get enough to operate.

Posted 3 years ago #
PsyKo
Member

Hello,

Thank you for your answers.

@gbulmer : I have access to a multi-meter, but no oscilloscope or more advanced tools. I already checked the voltage going into the Vin pin, is it's pretty stable at 5.03v. This looks normal to me.

I tried connecting each motor one at a time, and even tried to switch the motor, and only the one connected to pin 8 starts (I'm not sure about the pin number, since I don't have the quadcopter next to me). The other won't move.

@BJ Freeman : Thanks for your answer. The voltage looks good.

I will change my connection board (prototyped) to a insolated PCB to make sure every connection is right, and let you know.

Thanks

Posted 3 years ago #
crenn
Moderator

Where is the motors getting power from? Is it multiple batteries? If there is a battery for each motor, tie all the ground pins together.

Posted 3 years ago #
BJ Freeman
Member

Ok I assume your using digital lines as output.
of use a LED and resistor connected between the pin and VCC. you can see if the signals being sent by the pulsating or steady state.

Posted 3 years ago #
PsyKo
Member

Hello,

Sorry for not answering earlier.

@crenn : the motors are getting power from a single battery. All the +5 and GND coming from the ESC are tied together (I mean the +5 tied with other +5, and GND with other GND :) not +5 and GND together).

@BJ Freeman : Sorry but I'm not sure I understant your answer. Do you mean putting a led on the signal sent to the motors to see if they pulse ? Why would it be different depending of the power supply of the board ?

I had no occasion to make further tests on it, but I'll keep you in touch as soon as I get results...

Posted 3 years ago #
crenn
Moderator

Can you give us the code you're trying to run on the board? Which Maple Board (I'm assuming currently it's just the standard Maple Rev 5)? Which XBee modules are being used?

What are the timer settings being used?

Posted 3 years ago #
PsyKo
Member

I can't post... The forum does not accept my messages.

Edit : solved. Had to remove some links... weird

Posted 3 years ago #
PsyKo
Member

Honestly I think the code won't help, since everything works well when powered using USB (including motors, Xbeen IMU, and so on...). But I'll post it as soon as I have access to my quadcopter (I'm not home these weeks), because we never know.

If I remember well I use this library LibrairieServo
And call the writeMicroseconds to control the motors through the ESC. Again, it works perfectly while the board is being powered via the USB.

The maple is a Rev 5.
The Xbee modules are this one (if I remember well) - XBee 1mW Wire Antenna - Series 1
But the Xbee seem to work when using the Vin pin.

Is there any specific action that need to be done when using the Vin pin (except changing the jumper ? )

Thanks

Posted 3 years ago #
crenn
Moderator

When powering from USB, are you using the ESC connected to Vin as well? If not, are you grounding the battery and the GND of the robot together?

The Vin pin bypasses the selection jumper so it will work regardless of your jumper setting.

I'm more interested in the 'start-up' values of the PWM width you're using, increasing it by 10uS might be enough to work, but be cautious when doing so. Perhaps remove the propellers removes when testing. I'll look into the Servo library to see if I can't see something that would cause issues.

Posted 3 years ago #
PsyKo
Member

When powering from USB, the Vin is disconnected simply because I though that it might damage the board. Is it true or not ?
In this case, the GND from the ESC is indeed tied to the GND of the board.

The start values look good, but I don't have them in mind right now. I'll still check them. But I don't think they'll change regarding of the power mode, will they ?
The ESC of the single working motor is doing the start sequence beeps.
I can't remember what the other are doing.

What I will do, because we clearly lack of observation here, is to try to have access to an oscilloscope and check the voltage, and the PWM signals sent to the motors, both with USB power, and Vin power.
That should give us a clear view on the issue.

Anyway, thanks for your help so far ;)

Posted 3 years ago #
crenn
Moderator

It's more likely to damage the USB host (aka your computer) than the board itself, but should be within tolerance (I believe) of USB. However it is a good idea to have it unplugged when utilising the USB. Another option is to have the jumper on EXT while plugged into the USB as it will mean the Maple will be powered from the EXT connector but means that you can have the ESC connected to Vin without issue.

The start-up values shouldn't change regarding power mode, but I'm wondering if there is a problem with how the system is being set up. Are you plugging the battery into the motors before plugging in the USB cable? Also, are you giving the speed controllers a higher value than the 'initilisation'/minimum value before you set it to that value? If you don't, try that. I've had some speed controllers which do not initilise until they get the midpoint and then putting it into the minimum point (or until the signal is low enough).

Not a problem, sorry that I haven't been able to assist you further.

Posted 3 years ago #
PsyKo
Member

Thank you for your support crenn. It's really gret to see that the maple community is active.
What make me think that it's not related to my code or the initialisation sequence is that when powering from USB, I have my 4 motors spinning. I can control , stop, slow them, etc... A part of the PID algorithm for stabilization is also implemented on a single axis and was working quite fine. I decided to switch to the ESC power to avoid the effect of the USB wire on the Quadcopter.
So I can pretty much say that my starting sequence is right.

This issue is erally killing me.
I'll try and create a new PCB shield (I only have a shield on prototype board yet), to make sure all my connections are fine.

Posted 3 years ago #
xpomvid
Member

This is my quadcopter with Maple rev5 + 9 DOF - Razor IMU - AHRS.

http://youtu.be/2EGoGld0Z_4

Posted 3 years ago #

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