Motor Shield works with Leonardo, but not with Uno R4 Wifi

Projects Programming
1

I got Arduino Motor Shield Rev 3 and when I tested it with Arduino Leonardo it worked without issues in both directions and breaking, but when I bought Arduino UNO R4 Wifi, so that it could have Bluetooth without additional space it doesn't work at all, LEDs from motor pins don't even light up. Is there any code difference between these boards, considering that on Uno R4 Wifi website it does say that motor shield is supported? Here's my code (serial prints without issues):

int directionPinA = 12;
int pwmPinA = 3;
int brakePinA = 9;

int directionPinB = 13;
int pwmPinB = 11;
int brakePinB = 8;

void setup() {
  // put your setup code here, to run once:
  pinMode(directionPinA, OUTPUT);
  pinMode(pwmPinA, OUTPUT);
  pinMode(brakePinA, OUTPUT);
  pinMode(directionPinB, OUTPUT);
  pinMode(pwmPinB, OUTPUT);
  pinMode(brakePinB, OUTPUT);

  Serial.begin(9600);
}

void loop() {
  Serial.println("Forward");
  forward();
  delay(2000);
}


void forward() {

  digitalWrite(directionPinA, LOW);
  digitalWrite(directionPinB, LOW);

  digitalWrite(brakePinA, LOW);
  digitalWrite(brakePinB, LOW);

  analogWrite(pwmPinA, 500);
  analogWrite(pwmPinB, 500);
}
2

To check that it has been tested on the R4 see:-

Also note that while the library may be supported, the pin output capacity is only 8mA per pin compared with 20 to 30mA it is safe to run the R4 at. So it depends exactly on your schematic, which we need for a full answer.

3

But there's no library for the motor shield, at least docs don't say anything about one.

the pin output capacity is only 8mA per pin compared with 20 to 30mA it is safe to run the R4 at

Why would they then say that it's compatible here?

Also, here is the Motor Shield schematic:
arduino_MotorShield_Rev3-schematic.pdf (81,3 KB)

And the Uno R4 Wifi schematic:
UNO R4 WiFI - schematic.pdf (3,2 MB)

4

There seems little connect between what the marking team says and reality. Because the current capacity in my opinion is a vital incompatibility. I even started a thread about this about six months ago when the boards were first out.
Compatability Concern

5

I see, I guess I'll contact Arduino support and if there's no workaround I'll return both boards. Thanks a lot <3

7

I see that Arduino are now patting themselves on the back in their open source report, see Open Source Report

So they don't appear concerned about the quality of what they release.

8

After contacting support it looks like in the end, I made a mistake, because I didn't use an external power supply with only power coming from my laptop. I just assumed it would work without it since it did on Leonardo. Sorry for all the trouble and thanks for the help!

Also, I just really want to say here that Arduino has a lovely support considering how quickly they respond and how helpful they are!

9

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