Blinkentree

UNDER CONSTRUCTION

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Blinkentree
Meetings:	none
Type:	hardware
Status:	running
Members:
Contact Person:	slopjong (mail), prometheus (mail)
Tools
QrCode:

Introduction

What is this flashing green fir tree about?

As creative hackers, we thought it would be necessary to support the Christmas market of the commune of Strassen with something tiny, but creative. Result? The Blinkentree. Obviously it represents a green fir tree that is dorned with flashing LEDs which should represent the baubles of a 'real' tree.

A big thanks to all of you folks who purchsed a Blinkentree and thus supporting syn2cat Hackerspace.

Hacky Christmas!

Assembling the kit

If you purchased a non-assembled kit you have to put the devices on the board as on the picture.

How to program it on your own?

We designed our Blinkentree in a way you can customize it by yourself. You can define your own flashing patterns using the C language that you can transfer to your chip using the USBasp programmer.

Installing and confguring the tools

This section describes what you need to program the chip. First you need the toolchain with the compiler which translates your program text into bits and bytes that the controller can execute. We are using the GCC compiler which is part of the WinAVR (Windows) and CrossPack-AVR (Mac).

If you use Windows download WinAVR and follow the installtion guide. When the installer asks to make an entry in the PATH variable be sure this is checked.

For a mac you have to download CrossPack AVR. The toolchain is installed into /usr/local/CrossPack-AVR . Have a look if the installer did add an entry to the PATH variable by typing the following line in your shell (Terminal):

echo $PATH

If it doesn't contain /usr/local/CrossPack-AVR/bin, execute this in your shell:

echo -e " \n \n export PATH=/usr/local/CrossPack-AVR/bin:$PATH" >> ~/.profile

For both Windows and Mac chose a good editor like Notepad++ or Programmers Notepad for Windows and TextWrangler for Mac.

Coding

Programming new flashing patterns for your Blinkentree is very easy. Here is a sample code:

1. #include <avr/io.h> 

2. #include <util/delay.h>

4. int main(void) { 

6.     // configure the ports as outputs 

7.     DDRD = 0b11111111;

8.     DDRB = 0b11111111;

10.     while(1)

11.     {

12.             PORTB = 255;

13.             PORTD = 0;

15.             _delay_ms(400);

17.             PORTB = 0;

18.             PORTD = 255;

20.             _delay_ms(400);

21.     }

23. }

Save this code in the file main.c because this filename will be used in next sections.

In the first two lines you include one library for input/output (I/O) operations and one library for delay operations. In line 4 you define the main function that the Blinkentree jumps to when you switch it on. The DDRD and DDRB functions are used to configure the ports D and B. They're set to 0b11111111 which are binary numbers where each 1 stands for one pin of the port which has 8 pins. 1 means that the pin is set as an output wheras a 0 would be used to configure the pin as an input.

By setting the port B to high (255 = 0b11111111) in line 12 we turn on all the LEDs of that port. If you want to turn on only certain LEDs you have to set other values from the range 0 to 255 (0b00000000 to 0b11111111). You can use the decimal-binary converter to convert decimal numbers in binary numbers.

The while loop is used to execute the flashing pattern repeatedly. Otherwise the microcontroller would stop at the end of the main function. In other words the flashing pattern would be executed only one time.

On Suhas's blog you find more information about the I/O operations. If we have some time we will update this site to provide you with a mini coding tutorial for AVR microcontrollers.

Compiling and linking

After you're done with the programming, the code must be translated into machine code that can be executed by the microcontroller. Open your command line and change into the directory where your code file is.

There you you type in:

avr-gcc -Wall -Os -std=c99 -DF_CPU=1000000 -mmcu=attiny2313 -c main.c -o main.o 
avr-gcc -Wall -Os -std=c99 -DF_CPU=1000000 -mmcu=attiny2313 -o main.elf main.o 
avr-objcopy -O ihex -R .eeprom main.elf main.hex 

These commands are the same for Mac and Windows.

After that you have main.hex which is the translated code that will be loaded into the chip later.

Flashing the microcontroller

To flash the controller you need a programmer like the USBasp. On that homepage you find all information you need to build your own programmer but I'd recommend to come tu auer hackerspace in Strassen where you get help and support. We have the equipment like an etching machine to make electronic stuff in a professional way. If you have questions about our space just write an email to electronics[at]hackerspace.lu (please replace [at] by @).

TODO: Driver installation for f***ing Windoze.

With the programmer you are able to flash your controller. On Windows you execute

avrdude -c USBasp -p t2313 -U flash:w:main.hex -v -F

and on Mac

sudo avrdude -c USBasp -p t2313 -U flash:w:main.hex -v -F

Note

If you replaced the chip by a new one you have to configure it first before you can flash with the last command.

Then you have to execute

avrdude -cUSBasp -p t2313 -U lfuse:w:0x64:m -U hfuse:w:0xdf:m -U efuse:w:0xff:m 

on Windoze

and

sudo avrdude -cUSBasp -p t2313 -U lfuse:w:0x64:m -U hfuse:w:0xdf:m -U efuse:w:0xff:m 

on a Mac.