10. Output Devices – Group Kuriyama¶
This is group assignment page of Output Devices (Kuriyama Student) :
Group assignment¶
-
Stepper Motor
-
Neo Pixel
What we’ve done this week¶
Stepper Motor¶
Current limiting
The maximum current flowing to the stepper motor must be limited so that it does not exceed the rated current, so use the potentiometer on the driver to adjust as follows
In this method I am going to set the current limit by measuring the voltage (Vref) on the “ref” pin.
-
Take a look at the datasheet for your stepper motor. Note down it’s rated current. In this case using NEMA 17 200steps/rev, 12V 350mA.
-
Put the driver into full-step mode by leaving the three microstep selection pins disconnected.
-
Hold the motor at a fixed position by not clocking the STEP input.
-
Measure the voltage (Vref) on the metal trimmer pot itself while you adjust it.
-
Adjust the Vref voltage using the formula
Current Limit = Vref x 2
Nema 17 Stepping motor is rated for 350mA, you would adjust the reference voltage to 175mV.
Reference: Drv8825 Stepper Motor Driver Arduino Tutorial
NeoPixel LED tape¶
Output NeoPixel LED tape (60 lights) with 5V
Programming from Mac PC
You need to install “Fast LED” from Sketch > Include Library > Manage Libraries
#include <FastLED.h>
#define NUM_LEDS 60 // Number of LED light
#define DATA_PIN 10
CRGB leds[NUM_LEDS];
void setup() {
FastLED.addLeds<NEOPIXEL, DATA_PIN>(leds, NUM_LEDS);
}
void loop() {
// i = i + 1
for(int i = 0; i<NUM_LEDS; i++){
// Change the color here
leds[i] = CRGB( 255, 255, 255);
FastLED.show();
}
}
Current is 0.06A when a light is on.
Current is 0.08A when 3 lights are on.
Current is 1.44A when 60 lights are on with Yellow.
Current is 2.08A when 60 lights are on with White.
Links to Files and Code¶
Appendix¶
Drv8825 Stepper Motor Driver Arduino Tutorial