Tim Bruening - Fab Academy 2016

Week #8 - Embedded Electronics

In the eighth week we explore Embedded Programming.  We will take the PCBs we created in week #4 and program them to do something.  

The sample program I used can turn on the LED and set the on time and off time.  I will also experiment with  a program that enables the PCB to have an LED light when a pushbutton is pressed.

Here is a list of tasks as I see them for the eighth week.

• Read and explore the ATtiny44a data sheet.
  
• Research 'C' programming and methods.
  
• Download compiler and library programs to Ubuntu.
  
• Edit sample programs.
• Download sample programs and run on ATtiny44a controller.
• Edit second program and test it.
• Document the process and list any problems encountered.
• Include my code files in report.

Read and explore the ATtiny44a data sheet.

I downloaded the ATtiny4a data sheet and scanned through a lot of it.  Page #2, the pinout configuration of the ATtiny44a was helpful. 

Pages 66 & 67 which showed the register description also helped. I needed the pinouts to find pin PA7.

I used the register description for DDRA to control the blinking lights and the pushbutton circuit.

Research "C" programming methods.

I spent quite a bit of time trying to understand some of the codes used in "C" programming. I found a basic description in Wikipedia. Dennis Ritchie and Bell labs developed the code in the early 70's. 

The article also included some descriptions of codes used in programming, mostly operators. I found I needed much more information than was found in the Wiki. I then looked into tuturials for help. 

I scanned the one by Alex Allain. It was helpful to some extent. One other need I had was to refresh my comand of "Bash" commands. I found an "A to Z" index of bash commands at http://ss64.com/bash/

Download compiler and library files to Ubuntu.

My next attempt was to download some recommended compilers and librarys. The command I used was "sudo apt-get install avrdude". 

I then used the same command to load; "avr-libc", binutils-avr", and "gcc-avr". I now had the files I needed to play with some samples.

Edit sample programs.

I had two programs to play with. test.c and button.c At first I just tried substituting some of the values to see how they would affect the programming. 

I was not having much luck. After some counseling and some more experimentation I was able understand the process. 

I created a little flow chart that helps me to remember the steps I need. I know I am only substituting a few codes but I feel a liitle better about it.

Here is the flow chart I came up with.

• Copy an existing program
• Paste and rename it "newname.c"
• Make edits in new program
• Save program
• Copy a "make" program
• Paste and rename it "newname.c.make
• Edit newname.c.make - add correct project name and save
• run "make -f newname.c.make" - compiles the file
• run "sudo make -f newname.c.make program-usbtiny"
• Tryout new program on ATtiny controller

Download sample programs and run on ATtiny44a mini-controller.

Here is a screen image of some of the files I downloaded.

I choose to edit a program with a delay in it. Note the red colored text in "test.c". The delay is currently 50 ms.

test.c

 
#include <avr/io.h>    // this includes the infromation about the avr atmel micros

#include <util/delay.h>  //  delay header

int main()  // main function must have

{// this bracket opens main

                //DDRB = 0x04;

                DDRA = 0x80;  // sets the data direction register for port a or PA7 it is bitwise set

                while (1) // starts a while loop in this case it is a forever loop

                {// anything between here and the other bracket is in the loop.

                                PORTA = 0x80; // turns on one pin

                                _delay_ms(50);// waits

                                PORTA = 0x00;// turns off all of porta

                                _delay_ms(50);//waits

                }

                return 0;// need this becuase of int main

}  // this bracket closes main

Edit second program and test it.

Here the red text in "test1.c" chows the change from 50 ms to 1000 ms.

test1.c

 
#include <avr/io.h>    // this includes the infromation about the avr atmel micros

#include <util/delay.h>  //  delay header

int main()  // main function must have

{// this bracket opens main

                //DDRB = 0x04;

                DDRA = 0x80;  // sets the data dirction register for port a or PA7 it is bitwise set

                CLKPR = (1 << CLKPCE);

   CLKPR = (0 << CLKPS3) | (0 << CLKPS2) | (0 << CLKPS1) | (0 << CLKPS0);

                while (1) // starts a while loop in this case it is a forever loop

                {// anything between here and the other bracket is in the loop.

                                PORTA = 0x80; // turns on one pin

                                _delay_ms(1000);// waits

                                PORTA = 0x00;// turns off all of porta

                                _delay_ms(1000);//waits

                }

                return 0;// need this becuase of int main

}  // this bracket closes main

Here is an image of the PCB boards connected.

Here is a screen shot sending test1.c to the attiny44a.

Here is a screen shot of the circuit working.

Here is a screen shot sending timbutton.c to the attiny44a.

Here is a picture showing the push button working.

Document the process and list any problems encountered.

I definitely had to work hard to complete this assignment.  I am still quite the rookie when it comes to "C" programming.

My biggest problem was rememberig the sequences I needed to take to edit the file, compile the file, then run the file to see the delay.

Include my code files in report.

Tim's files for Week #8.

*.c, *.hex and *.make files.