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Topic: (Solved)Arduino Uno only 1.5 volts from digital outputs instead of 5 volts (Read 4 times) previous topic - next topic

wikitjuggla

i am trying to use my arduino with a rc receiver without pwm and a motor shield. i set my output speed pins to HIGH. i have 4 digital inputs for the receiver which just inputs 5 volts to the inputs and then is supposed to output to the corresponding motor shield pins and 6 digital outputs for the motor shield. i am using the if statement in my code telling the arduino to put HIGH power to the motor shield pins if it receives the high signal from the input pins but my arduino won't put out a steady 5 volts on the outputs, it only puts out 1.5 volts and sometimes it will vary on its own up to the 5 volts. when i run the motor shield demo sketch my arduino works just fine but i have tried 3 different sketches to make my set up work and can not seem to get it to work and have tried many different tests and determined it seems to be a problem with my arduino itself. Is it possible that this sketch is too much for the arduino to process? here is a copy of my primary code if someone thinks it is a sketch  problem. help would be greatly appreciated.

Code: [Select]
// Arduino code
// pins for r/c receiver
const int left = 2;
const int right = 3;
const int forword = 4;
const int reverse = 5;

// motor shield pins
const int pinI1=8;//define I1 interface
const int pinI2=11;//define I2 interface
const int speedpinA=9;//enable motor A
const int pinI3=12;//define I3 interface
const int pinI4=13;//define I4 interface
const int speedpinB=10;//enable motor B


void setup()
{
 pinMode(pinI1,OUTPUT);
 pinMode(pinI2,OUTPUT);
 pinMode(speedpinA,OUTPUT);
 pinMode(pinI3,OUTPUT);
 pinMode(pinI4,OUTPUT);
 pinMode(speedpinB,OUTPUT);
 pinMode(left,INPUT); //my rc reciever input pins
 pinMode(right,INPUT); //which are not pwm compatable
 pinMode(forword,INPUT); //they put out what ever voltage
 pinMode(reverse,INPUT); //that is powering the reciever

}

void loop() {

 if (digitalRead(left) == HIGH)  {
   motor1_reverse();  // move left motor (motor1) reverse
   motor2_forward();  // move right motor (motor2) forward - this should make the robot turn left
 } else {
   motor1_stop();  //otherwise, stop both motors
   motor2_stop();
 }
 
 if (digitalRead(right) == HIGH) {
   motor1_forward(); // move left motor (motor1) forward
   motor2_reverse(); // move right motor (motor2) reverse - this should make the robot turn left
 } else {
   motor1_stop();
   motor2_stop();
 }
 
 if (digitalRead(forword) == HIGH) {
   motor1_forward();  // move motor1 forward
   motor2_forward();  // move motor2 forward
 } else {
   motor1_stop();
   motor2_stop();
 }
 
 if (digitalRead(reverse) == HIGH) {
   motor1_reverse(); // move motor1 reverse
   motor2_reverse(); // move motor2 reverse
 } else {
   motor1_stop();
   motor2_stop();
 }
}

// These functions make it easier to define the direction of each motor and the appropriate digitalWrite commands, so you can just call motor1_forward();
// You can change the code or names of any of these functions if your motors do not go the direction that they should.
void motor1_forward(){
 digitalWrite(pinI1, HIGH);
 digitalWrite(pinI2, LOW);
 digitalWrite(speedpinA, HIGH);
}

void motor1_reverse(){
 digitalWrite(pinI2, HIGH);
 digitalWrite(pinI1, LOW);
 digitalWrite(speedpinA, HIGH);
}

void motor1_stop(){
 digitalWrite(pinI1, LOW);
 digitalWrite(pinI2, LOW);
 digitalWrite(speedpinA, LOW);
}

void motor2_forward(){
 digitalWrite(pinI3, HIGH);
 digitalWrite(pinI4, LOW);
 digitalWrite(speedpinB, HIGH);
}

void motor2_reverse(){
 digitalWrite(pinI4, HIGH);
 digitalWrite(pinI3, LOW);
 digitalWrite(speedpinB, HIGH);
}

void motor2_stop(){
 digitalWrite(pinI3, LOW);
 digitalWrite(pinI4, LOW);
 digitalWrite(speedpinB, LOW);
}  

spcomputing

You need to put your code in a "Code Block" (The pound (#) icon).

Anyhow, check out this thread:
http://arduino.cc/forum/index.php/topic,122825.0.html

Sounds like it might have the tips you are looking for.

Grumpy_Mike

Quote
Is it possible that this sketch is too much for the arduino to process?

No, a sketche's complexity has no effect on the digital output pins.
From your description it sounds like you are not setting the pins to be an output, however that code shows you are. The other thing is that you might be overloading the outputs, that is drawing too much current from the.
A schematic of what you have would be good.

fungus


i am trying to use my arduino with a rc receiver without pwm and a motor shield. i am using the if statement in my code telling the arduino to put HIGH power to the motor shield pins if it receives the high signal from the input pins but my arduino won't put out a steady 5 volts on the outputs, it only puts out 1.5 volts and sometimes it will vary on its own up to the 5 volts.


You're trying to drive motors directly from the Arduino pins? It won't work, motors draw too many amps. That's why you need a motor shield.

Don't continue without one. You can damage your Arduino.
No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

MarkT

We are told there is a motor shield, the output pins are driving that.

We are also told the motor demo works.

My suspicion is something to do with the supply voltage or common grounding is awry - a schematic of the wiring might be useful, but I'd suggest checking that all the supply voltages are correct during operation and all grounds are common.
[ I won't respond to messages, use the forum please ]

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