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Week 9 - Output Devices

Assignments | Week 9 | Output Devices

Group assignment

  • Measure the power consumption of an output device.
  • Document your work on the group work page and reflect on your individual page what you learned.

Individual assignment

  • Add an output device to a microcontroller board you’ve designed and program it to do something.

Learning outcomes

  • Demonstrate workflows used in controlling an output device(s) with MCU board you have designed.

Introduction

In this documentation I will show the programming processes for an output device. I’ll be using the PCB that I made in the previous weeks:

Hero Shot

Programming an output device

What do I have to achieve?

My output board contains:

  • A Button Omron B3SN
  • An RGB light chip : Adafruit’s Neopixel - aka WS2812B (also WS2811/WS2812/WS2813, also supported in lo-speed mode) - a 3 wire addressable LED chipset

I’m going to program a little memory game, using the Serial output as interface and the board as an input (Button) + output (RGB LED) device.

What did I do?

Materials:

  • My PCB
  • ArduinoIDE for coding
  • Google Chrome, a web browser for research and datasheet
  • KICAD to have access to the PCB’s design and pinout

In KICAD I opened my PCB design

I tried to find a way to export the pinout of the pcb in KICAD. But I didn’t find it. So I just modified the F.Silkscreen layer in KICAD’s PCB editor. I double click an electronic component and changed

This board works with a programmer. I’ll be using this Serial-UPDI programmer, designed and made by my instructor Stephane: https://gitlabsu.sorbonne-universite.fr/mullerst/serialupdi-programmer

I used an existing code to test if my button work

#define BUTTON_PIN 4
int counter=0;

void setup()
{
  Serial.begin(9600);
  pinMode(BUTTON_PIN, INPUT_PULLUP);

}

void loop()
{
  byte buttonState = digitalRead(BUTTON_PIN);

  if (buttonState == LOW) {
      counter++;    
      Serial.print("Button is pressed ");
      Serial.print(counter);
      Serial.println("times"); 
  }
  delay(10);
}

But the ArduinoIDE printed an error as follow:

Sketch uses 1666 bytes (46%) of program storage space. Maximum is 3584 bytes.
Global variables use 61 bytes (23%) of dynamic memory, leaving 195 bytes for local variables. Maximum is 256 bytes.
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x30
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0x20
avrdude: stk500_getsync() attempt 3 of 10: not in sync: resp=0x30
avrdude: stk500_getsync() attempt 4 of 10: not in sync: resp=0x20
avrdude: stk500_getsync() attempt 5 of 10: not in sync: resp=0x30
avrdude: stk500_getsync() attempt 6 of 10: not in sync: resp=0x20
avrdude: stk500_getsync() attempt 7 of 10: not in sync: resp=0x30
avrdude: stk500_getsync() attempt 8 of 10: not in sync: resp=0x20
avrdude: stk500_getsync() attempt 9 of 10: not in sync: resp=0x30
avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0x20
Failed uploading: uploading error: exit status 1

Then I checked the USB connection, and make sure I chose the right board name of the microcontroller. Then I found what was wrong, I didn’t select the programmer. So I clicked on Tool > Programmer > SerialUPDI - SLOW:57600 baud

The upload went smoothly, and the copy/paste program worked (which is a good sign!)

The program works as I press the buttun on my board!

Now I would like to make the RGB led

I searched on internet: how to program WS2812B. I found a website, and the most important library to this chip.

I found a documentation by RishabhL on Instructables.com : https://www.instructables.com/Basic-of-FastLED/

I followed the documentation by installing the FastLed library and added the basic instructions to write an led: https://github.com/FastLED/FastLED/wiki/Basic-usage

#include <FastLED.h>

#define BUTTON_PIN 2 // Analog/Digital Pin num
#define NUM_LEDS 1 // Number of led that are being used
#define DATA_PIN 3 // Analog/Digital Pin number of the rgb led
int counter=0;

CRGB leds[NUM_LEDS];

void setup()
{
  Serial.begin(9600);
  FastLED.addLeds<WS2812B, DATA_PIN>(leds, NUM_LEDS);
  pinMode(BUTTON_PIN, INPUT_PULLUP);
}

void loop()
{
  byte buttonState = digitalRead(BUTTON_PIN);

  if (buttonState == LOW) {
      leds[0] = CRGB::Red; 
      FastLED.show();
      counter++;  
      Serial.print("Button is pressed ");
      Serial.print(counter);
      Serial.println("times"); 
  }
  delay(100);
}

The first test failed.

warning: #warning "No pin/port mappings found, pin access will be slightly slower. See fastpin.h for info." [-Wcpp]
 #warning "No pin/port mappings found, pin access will be slightly slower. See fastpin.h for info.

note: #pragma message: No hardware SPI pins defined.  All SPI access will default to bitbanged output
 #      pragma message "No hardware SPI pins defined.  All SPI access will default to bitbanged output"

In file included from c:\Users\lauri\Documents\Arduino\libraries\FastLED\src/FastLED.h:62:0,
                 from C:\Users\lauri\Documents\Arduino\output_rgb\output_rgb.ino:1:
c:\Users\lauri\Documents\Arduino\libraries\FastLED\src/fastpin.h: In instantiation of 'class FastPin<3>':
c:\Users\lauri\Documents\Arduino\libraries\FastLED\src/platforms/avr/clockless_trinket.h:107:49:   required from 'class ClocklessController<3, 5, 13, 8, (EOrder)66, 0, false, 10>'
c:\Users\lauri\Documents\Arduino\libraries\FastLED\src/chipsets.h:740:7:   required from 'class WS2812Controller800Khz<3, (EOrder)66>'
c:\Users\lauri\Documents\Arduino\libraries\FastLED\src/FastLED.h:139:52:   required from 'class WS2812B<3, (EOrder)66>'
c:\Users\lauri\Documents\Arduino\libraries\FastLED\src/FastLED.h:368:39:   required from 'static CLEDController& CFastLED::addLeds(CRGB*, int, int) [with CHIPSET = WS2812B; unsigned char DATA_PIN = 3; EOrder RGB_ORDER = (EOrder)66]'
C:\Users\lauri\Documents\Arduino\output_rgb\output_rgb.ino:9:56:   required from here
c:\Users\lauri\Documents\Arduino\libraries\FastLED\src/fastpin.h:261:2: error: static assertion failed: Invalid pin specified
  static_assert(validpin(), "Invalid pin specified");
  ^~~~~~~~~~~~~

exit status 1

Compilation error: exit status 1

To debug this, I checked several times the PIN number

With desperation, I closed and reopened ArduinoIDE, I tried to replace the PIN number by 1, 2, 3, 4, 5, 6, 7, 8. The error remains the same. Now I can be sure that the problem does not come from the code, neither ArduinoIDE. I’ll seek help from my instructor when I’ll be in the lab.

Meanwhile, I found an github issue online, someone has faced the same problem as me. https://github.com/FastLED/FastLED/issues/973

The answer to this issue : “Thanks for opening this issue. Probably it’s a small piece of work if you’d like to try adding the port/pin mappings yourself. If that’s not something you’re familiar with, perhaps someone else can help out here.”

I browsed the datasheet of ATtiny412

My instructor took a look on the code and checked with me if the microcontroller I’m using is supported by the library. The answer: No.

He reccomanded a library : tinyNeoPixel

I was quite confused by the basic code of the official documentation, because then I found a documentation page of a Fab’Academy 2020 student (William from Charlotte)

I copy-paste the code and modified the pin number. 

#include <tinyNeoPixel.h>

#define PIN 3

// Creating a tinyNeoPixel object: Parameters in the constructor are (# of LEDS, PIN, Color System)
tinyNeoPixel strip = tinyNeoPixel(5, PIN, NEO_GRB + NEO_KHZ800); 

void setup() {
  strip.begin();
  strip.show(); 
}

void loop() {
  strip.setPixelColor(0, strip.Color(0,0,255)); 
  strip.show();
  delay(50);
}

Thanks to Stéphane!