Thomas Laubach

After engraving the traces and cutting the border, the finished board looked decent (see below image) with clearly separated traces. I also validated the electrical connections with a multimeter.

Soldering the components

With the script "bom.ULP" in EAGLE, I obtained a dialog window that allows to export a bill of materials for a project (see below image). You can export the data in either text format, HTML, or in CSV (comma separated values). I am now waiting for some electrical components to arrive. After that, I can go ahead with the soldering.

I have added the resistor by the name "USB VBUS R3" that serves as a "bridge". Its value should be 0 Ohm, therefore. The two components named "USB_Z1" and "USB_Z2" are varistors, although they resemble Zener diodes. Although one person recommended that, I am not sure whether I can replace the varistors by Zener diodes. I did some research in the World Wide Web. Obviously, most people use Zener diodes and varistors interchangeably. With the Arduino Micro, they are used to prevent over-voltage from the USB. I need to keep in mind that, due to their functioning as a current blocker up to a certain voltage, I must solder them "backwards" in comparison to normal diodes.

When you export the bill of materials in text format, you get something like the following:

        Stückliste exportiert aus /Users/tlaubach/Desktop/FabAcademy/kalirepo/fablabkamplintfort/students/125/week11_files/ShrunkenMicro/ShrunkenMicro_EAGLEschematic/Thomas_ArduinoMicro_270416.sch am 13.05.16 14:32

Part         Value         Device             Package             Description                          MF MPN OC_FARNELL OC_NEWARK
ANALOGIN                   M01PTH_LONGPAD     1X01_LONGPAD        Header 1                                                        
ARDUINO      ATMEGA32U4-AU ATMEGA32U4-AU      TQFP44                                                                              
AVCC2_C7     1uF           CAP-UNPOLARIZEDFAB C1206FAB                                                                            /Users/tlaubach/Desktop/FabAcademy/kalirepo/fablabkamplintfort/students/125/week11_files/images/billOfMaterials.jpg
CRYSTAL_C12  22pF          CAP-UNPOLARIZEDFAB C1206FAB                                                                            
CRYSTAL_C13  22pF          CAP-UNPOLARIZEDFAB C1206FAB                                                                            
J3           USB-MICRO!!!  MYCON2_USB-MINI-B  CON2_USB_MICRO_B_AT                                                                 
J4           3x2M          PINHD-2X3          2X03                PIN HEADER                                                      
JOYSTICK                   M08LONGPADS        1X08_LONGPADS       Header 8                                                        
PWR                        M02PTH3            1X02_LONGPADS       Standard 2-pin 0.1" header. Use with                            
Q1           16MHz KX-7    CSM-7X-DU          CSM-7X-DU           SMD CRYSTAL                                 unknown    unknown  
RESET_C10    100N          CAP-UNPOLARIZEDFAB C1206FAB                                                                            
RESET_C11    100N          CAP-UNPOLARIZEDFAB C1206FAB                                                                            
RESET_R1     10K           RESISTOR1206       1206                Resistor                                                        
UCAP_C2      1uF           CAP-UNPOLARIZEDFAB C1206FAB                                                                            
UGND_C6      100n          CAP-UNPOLARIZEDFAB C1206FAB                                                                            
USB_RP3A     22R           RESISTOR1206       1206                Resistor                                                        
USB_RP3B     22R           RESISTOR1206       1206                Resistor                                                        
USB_VBUS_C14 22u           CAP-US1206FAB      C1206FAB                                                                            
USB_VBUS_R3                RESISTOR1206       1206                Resistor                                                        
USB_VUSB_C9  100n          CAP-UNPOLARIZEDFAB C1206FAB                                                                            
USB_VUSB_R2  10K           RESISTOR1206       1206                Resistor                                                        
USB_Z1       CG0603MLC-05E ZENER_DIODESOD123  SOD123              zener diode                                                     
USB_Z2       CG0603MLC-05E ZENER_DIODESOD123  SOD123              zener diode      
    

Working joystick example with a Satshakit

May 23rd.: I have not yet managed to solder the shrunken Arduino Micro board. I will finish this assignment with a Satshakit I have made but would like to solder the Micro board when time permits.

I connected the Adafruit Arcade joystick shown above to my Satshakit. The joystick comprises of four independently usable switches with "Normally Open (NO)" characteristics. This means no current will flow through the joystick when it is not pushed in any of the eight directions. The black wire from the joystick needs to be connected to GND, the remaining four wires represent the UP, DOWN, LEFT, RIGHT (or NORTH, WEST, EAST, SOUTH) directions. I connected them to the Satshakit's digital pins 5 - 8. For the digital pins, I activated their internal pull-up resistors. I did not use a fire button for this demonstration. A fire button would be treated like the other switches. For programming, I have also attached an FTDI cable to the Satshakit (see below image).

On the software side, using the internal pull-up resistors has an interesting side effect: the scan logic for the joystick needs to be reversed. When the joystick is left alone, the voltage at the digital pin is HIGH, and LOW when the joystick is pushed in one of the four directions. If the joystick is pushed diagonally, the voltages at two digital pins are LOW.

I wrote below small Arduino sketch that demonstrates how an Arduino can accept and interpret input from the Adafruit Small Arcade joystick. There is a nice tutorial on how to use the joystick with an Arduino Leonardo here as a USB keyboard device. Although the Arduino Uno cannot mimic a USB keyboard without extra labor, it can query the joystick.

// This small program demonstrates how an Arduino Uno Sketch can read input from the Adafruit digital Arcade joystick
// (see https://www.adafruit.com/product/480 and https://brainy-bits.com/tutorials/leonardo-arcade-controller/)
// Author: Thomas Laubach

// Include libraries for adafruit matrix
#include    // Core graphics library
#include  // Hardware-specific library
#include  // Necessary to keep up data in program memory

// Setup Adafruit matrix
#define CLK 50
#define OE  51
#define LAT 10
#define A   A0
#define B   A1
#define C   A2
#define D   A3
//RGBmatrixPanel matrix(A, B, C, D, CLK, LAT, OE, false);

// Joystick 1
int joyUP = 8;
int joyDOWN = 7;
int joyLEFT = 5;
int joyRIGHT = 6;
int joyFIRE = 9;


void setup()
{
  // Initialize serial connection
  Serial.begin(9600);

  // Initialize random number generator
  randomSeed(analogRead(40));

  // Initialize joysticks and  buttons
  pinMode(joyLEFT, INPUT); // DOWN
  pinMode(joyRIGHT, INPUT); // UP
  pinMode(joyUP, INPUT); // LEFT
  pinMode(joyDOWN, INPUT); // RIGHT
  pinMode(joyFIRE, INPUT);

  // Activate internal pull-up resistors
  digitalWrite(joyLEFT, HIGH);
  digitalWrite(joyRIGHT, HIGH);
  digitalWrite(joyUP, HIGH);
  digitalWrite(joyDOWN, HIGH);
  digitalWrite(joyFIRE, HIGH);

  // Initialize matrix and define text mode
  //matrix.begin();
  //matrix.setTextSize(1);
  //matrix.setTextWrap(false);
}


void loop()
{
  if  (digitalRead(joyUP) == LOW) // NORTH
  {
    Serial.print("\nMove North");
    
    if  (digitalRead(joyRIGHT) == LOW)
    {
      Serial.print("\nMove Northeast");
    }
    else if (digitalRead(joyLEFT) == LOW)
    {
      Serial.print("\nMove Northwest");
    }
  }
  else if (digitalRead(joyDOWN) == LOW) // SOUTH
  {
    Serial.print("\nMove South");
    
    if  (digitalRead(joyRIGHT) == LOW)
    {
      Serial.print("\nMove Southeast");
    }
    else if (digitalRead(joyLEFT) == LOW)
    {
      Serial.print("\nMove Southwest");
    }
  }
  else if (digitalRead(joyLEFT) == LOW) // WEST
  {
    Serial.print("\nMove West");
  }
  else if (digitalRead(joyRIGHT) == LOW) // EAST
  {
    Serial.print("\nMove East");
  }
}

The sketch has specific code for using the Adafruit 32x32 RGB Matrix Panel. As soon as the libraries for the LED matrix panel are used which happens when the LED matrix gets initialized, the program stops working. Instead of printing to the serial port a message whenever one of the directional switches on the joystick are being operated, it permanently reports that the joystick has been pulled even if this is not the case. I can only speculate why this happens. It might be due to that no wires between LED matrix and Arduino were connected. This means the pins necessary for controlling the LED matrix were floating but read and used by the program. Incidentally, the computer reported that the USB port the Arduino was linked to consumed too much power.

Over the day, I tried to solve the incident using different strategies. One was to provide current to the circuit because I had and have trouble to understand what makes the joystick circuit work although no current was sent into the joystick. The result I got was basically the same. One colleague suggested to reverse the current flow. I fed 5V into the black wire of the joystick and attached the other wires to the digital pins of the Satshakit, always with the internal pull-up resistors activated to prevent overcurrent. It would have been more efficient to consistently measure the wiring as I was loosing time with guessing and trial and error.

The fact that the program did not work together with the LED matrix and its libraries bothers me. So far, I could only guess but not track down the cause for the faulty behavior of the circuit and the program.

My VGS Board with Joystick and LED RGB Matrix Panel

I have tested the joystick as an input device and the LED matrix panel as output device with the board that I have made for my final project. It works flawlessly. Please watch the movie below for some impressions.

Source files

Lessons learned

• I learned and enjoyed to use the Roland Mill.
• When dealing with electronics, guessing is not adequate. You need to either know or measure.