I have an Arduino UNO R3 with an Adafruit Motor Shield v2.
- The power comes from a huge, fully loaded 12V 7Ah lead battery.
- The battery is connected to the terminal on the motor shield, the VIN jumper is also set.
- A 12V DC motor is connected to the shield. It consumes 200mA at max speed.
- Arduino runs fine, I can measure 12V at the VIN pin
The problem:
When I enable the motor and set its speed to maximum (255) the motor rotates too slowly. I measured the output voltage at the motor's terminal, which is only 4.5V and not 12V as I expected.
When measuring at the VIN pin on the Arduino, I can see the 12V...
Motor Shield v2 not enough voltage?
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- adafruit_support_bill
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Re: Motor Shield v2 not enough voltage?
Do you mean 200mA with no load? What is the stall-current rating? Please post a link to a spec sheet if possible.It consumes 200mA at max speed.
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Re: Motor Shield v2 not enough voltage?
The motor consumes 200mA peak current at 12V and full speed with no load attached to it (I tested that with a power supply at work).adafruit_support_bill wrote:Do you mean 200mA with no load?
Even with a load (my bare hands trying to stop it) the current does not exceed 250mA.
By the way: It is a small gear motor (30 RPM).
Sadly there was/is no datasheet available. But I hope the details mentioned above suffice?adafruit_support_bill wrote: Please post a link to a spec sheet if possible.
Is there a way to debug this? Maybe perform measurements somewhere on the motor shield?
Maybe something is broken?
- adafruit_support_bill
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Re: Motor Shield v2 not enough voltage?
Measure the voltage on the motor terminals with the motor disconnected.
Also try driving the other motor channels in your code and measure the voltages on those.
If you post some photos of the front & back of the shield, as well as one showing how you have everything connected we'll see if we can spot any problems.
Also post the code you are using.
Also try driving the other motor channels in your code and measure the voltages on those.
If you post some photos of the front & back of the shield, as well as one showing how you have everything connected we'll see if we can spot any problems.
Also post the code you are using.
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Re: Motor Shield v2 not enough voltage?
Thanks for your support! (BTW: th support in this forum is truely amazing)
Here are the news:
- Voltage without motor: 12V => The voltage seems to break in as soon as the motor is connected
- Behavior on terminal 2: the same as on terminal 1
One thing just came to my mind:
Once I connected the 12V power supply to the motor shield with reversed polarity. A little bit of smoke came out of somewhere. I thought it was the arduino, which I replaced (on the motor shield's website it said that there was some sort of protection?).
=> Could that have done the kind of damage that would explain the current behavior?
(for example there are two dents on the IC next to the motor terminal. Do they belong there?)
The code I'm using:
Here are the news:
- Voltage without motor: 12V => The voltage seems to break in as soon as the motor is connected
- Behavior on terminal 2: the same as on terminal 1
One thing just came to my mind:
Once I connected the 12V power supply to the motor shield with reversed polarity. A little bit of smoke came out of somewhere. I thought it was the arduino, which I replaced (on the motor shield's website it said that there was some sort of protection?).
=> Could that have done the kind of damage that would explain the current behavior?
(for example there are two dents on the IC next to the motor terminal. Do they belong there?)
The code I'm using:
Code: Select all
Adafruit_DCMotor *myMotor;
Adafruit_MotorShield motorShield = Adafruit_MotorShield();
void setup() {
// Init the motor shield
myMotor = motorShield.getMotor(2);
motorShield.begin();
myMotor->setSpeed(255);
myMotor->run(FORWARD);
}
void loop() {
delay(1000);
}
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- adafruit_support_bill
- Posts: 88152
- Joined: Sat Feb 07, 2009 10:11 am
Re: Motor Shield v2 not enough voltage?
That certainly does look like a blown chip. The reverse protection circuit protects against reversal of power to the motors. But you have the VIN jumper installed, which couples the motor supply to the Arduino supply. http://learn.adafruit.com/adafruit-moto ... ing-motors
The Arduino has no protection against reverse voltage on the VIN pin. So pumping -12v into the 5v regulator would cause serious damage to the Arduino and anything attached.
The logic on the motor shield draws power from the Arduino 5v regulator, so given the scenario you describe, I'd expect it is toast. And given the high current capabilities of SLA batteries, some smoke is to be expected.
If you mess with motors long enough, you are bound to blow something up sooner or later. Welcome to the world of motor control. I am awarding you this badge: http://www.adafruit.com/products/565
If you contact [email protected] with a link to this thread we can include one in your next order.
The Arduino has no protection against reverse voltage on the VIN pin. So pumping -12v into the 5v regulator would cause serious damage to the Arduino and anything attached.
The logic on the motor shield draws power from the Arduino 5v regulator, so given the scenario you describe, I'd expect it is toast. And given the high current capabilities of SLA batteries, some smoke is to be expected.
If you mess with motors long enough, you are bound to blow something up sooner or later. Welcome to the world of motor control. I am awarding you this badge: http://www.adafruit.com/products/565
If you contact [email protected] with a link to this thread we can include one in your next order.
-
- Posts: 21
- Joined: Fri Jan 31, 2014 11:09 am
Re: Motor Shield v2 not enough voltage?
The arduino and motor shield were working quite well although the magic smakoe was gone
(Except for the missing power of course)
So a new motor shield it is! (you don't ship to germany, do you?)
(Except for the missing power of course)
So a new motor shield it is! (you don't ship to germany, do you?)
- adafruit_support_bill
- Posts: 88152
- Joined: Sat Feb 07, 2009 10:11 am
Re: Motor Shield v2 not enough voltage?
We do ship worldwide: http://www.adafruit.com/shippinginfo/(you don't ship to germany, do you?)
Please be positive and constructive with your questions and comments.