Embedded Bike Lights + ATTiny = More Flashiness

I have been slowly working towards a mobile bike light show. The most recent step in that project has been to create a small PCB that I can place inside the wheel with an MCU that will be able to control the flashing of the lights.

I have already done several prototypes of such a board. Here is video of the different modes I have programmed in. Sorry that LEDs dont glow very brightly. I was VERY conservative with the current limiting resistor because I didn't want to risk blowing any (they would be a pain to replace). The power supply is putting out around 200mA but it could be closer to 400mA.

CS50 - Introduction to computer science atStanford

While I was cruising youtube for tutorials on programming I stumbled across some videos for an introductory computer science class at Stanford University. It turned out that the entire course is available online for free.

The Course is stanfords flagship unt for their faculty of computer sciences. And, because of the high status of the course and importance to Stanford as a marketing tool, you can see that they have put a lot of effort into the course (they have their own merch).

Course is available at CS50.net
https://www.cs50.net/

The lecturers are really entertaining I watched all 24 one and a half hour lectures in a few weeks. Although, I still havent got through the tutorials :D

I will be sure to [ost my solutions when/if I do them.

The New Boston C++ Tutorials (moved)

I have just completed working through a 70+ video series on the basics of C++. Bucky is a young programmer-educator-blogger that offers video courses in many computer languages. He also offers Biology classes and a Bear-Grylis-style survival course among other things. Check it out.
http://thenewboston.org/

VU Meter using Adafruits LED strip

I have made a VU meter using an ISP addressable LED strip. The project is made based on the project done by Jeremy Blum. See the video tutorial here. The rest of the his arduino series is excellent.

The electronics I have used are the same. This is a basic amplifier circuit that keeps only the peaks of the sinusoidal audio signal.

The code his tutorial produces gives a piece of code that has the LED change colour depending on the level of the audio output. The colour then moves down the LED strip at a fixed rate.

My code takes the signal level from the audio and converts it into a certain number of illuminated LEDs. Giving a VU meter effect. The code I used, which was barbarically adapted from Jeremy´s is below:

//Basic VU meter by Cameron Stewart http://hackingismakingisengineering.blogspot.com/2012/09/vu-meter-using-adafruits-led-strip.html
//Based on Jeremy Blum´s Design available at http://www.jeremyblum.com/2011/12/25/tutorial-14-for-arduino-holiday-lights-and-sounds/
//SPI Library
#include "SPI.h"
//Include Library for LED strip using Ada fruit´s library
#include
//Analog Audio Input Pins - from OPamp circuit.
int left_channel = 0;
int right_channel = 1;
//Light Control Pins
int light_data = 2;
int light_clk = 3;
//Setup Strip Constants
const int length = 32;
const int half = length;
//Creat strip object from Object Library
LPD8806 strip = LPD8806(length, light_data, light_clk);
//Initialise strip array.
uint32_t strip_array[length];
void setup()
{
  //Start serial for debugging
  Serial.begin(9600);
  //Fill pixel arrays with zeros
  for(int i=0; i  {
    strip_array[i] = 0;
  }
  //Initialize Strip
  strip.begin();
  strip.show();
}
void loop()
{
  //Uncomment this section to open the serial window for debugging
  //Serial.print("left:    ");
  //Serial.print(analogRead(left_channel));
  // Serial.print("right:    ");
  // Serial.println(analogRead(right_channel));
  //Determine power level
  int power = map(analogRead(right_channel), 0, 800, 0, 32);
  Serial.println(power);
  //Original Strand test function that came with the LED strip
  //colorChase(strip.Color(127, 127, 127), 10); // White

  //My new VU function
  uvMeter(strip.Color(127, 127, 127), power); // White
  //Display the new values
  strip.show();
  delay(0);
}
void uvMeter(uint32_t c, int pow) {
  int i;
  // Start by turning all pixels off:
  for(i=0; i // turn on all pixels below the peak level
  for(i=0; i<=pow; i++) strip.setPixelColor(i, c);

  // Display LEDs
  strip.show();
}
void colorChase(uint32_t c, uint8_t wait) {
  int i;
  // Start by turning all pixels off:
  for(i=0; i  // Then display one pixel at a time:
  for(i=0; i    strip.setPixelColor(i, c); // Set new pixel 'on'
    strip.show();              // Refresh LED states
    strip.setPixelColor(i, 0); // Erase pixel, but don't refresh!
    delay(wait);
  }
  strip.show(); // Refresh to turn off last pixel
}

After the first iteration I plan to add a few more features to the code to make the effect a little more tidy. Future improvmentes:

• Dynamic ranging - to make use of the full LED strip.
• Double/Triple sampling - to clean up the signal a bit
• A top cap bar - similar to the effect in modern stereo VU meters
• Stereo support 
• Frequency filtering.