week 10

output devices

Introduction

This week's assignment was to design and make a board and include at least one output device and program it. I chose to do charlieplexing with an attiny 45 and six leds.

BOM

component	quantity
Attiny 45	1
red leds	6
resistor 100 ohms	3
isp header	1
power header	1
jumper wire	1

Designing the board

I designed the board first using eagle. i started by placing my components on the schematic

I then connected the wires and nets to the respective pins

placing

routing

outcome

fab modules

below shows my fab modules settings for making the board

This board turned out to be too big so i set off to redesign it and make it smaller and compact

Redesigning the board

I set off to redesign the board and change the size of the board

placing the components

routing

final outcome

fabbed and stuffed board

Programming

To program the board i connected it to my fab isp programmer used the following command on command prompt

avrdude -c  usbtiny  -p t44 -u -U flash:w:charlie.c.hex:i

The code

#define F_CPU 8000000UL
#include 
#include 

void led1on()
{
  DDRB=0b00101000;
  PORTB=0b00100000;
}
void led2on()
{
  PORTB=0x00;
  DDRB=0x00;
  DDRB |=(1<<5)|(1<<3);
  //PORTB=0b1000;
  PORTB |=(1<<3);
  PORTB &=~(1<<5);

}
void led3on(){
  DDRB=0b00011000;
  PORTB=0b00001000;
}
void led4on(){
  DDRB=0b00011000;
  PORTB=0b00010000;
}
void led5on(){
  DDRB=0b00110000;
  PORTB=0b00100000;
}
void led6on(){
  DDRB=0b00110000;
  PORTB=0b00010000;
}
int main(){
  //led3on();
  while (1){
    led1on();
    _delay_ms(1000);
    led2on();
    _delay_ms(1000);
    led3on();
    _delay_ms(1000);
    led4on();
    _delay_ms(1000);
    led5on();
    _delay_ms(1000);
    led6on();
    _delay_ms(1000);

  }
}

In the above code i began by defining the different functions for putting the different leds on the code

void led1on()
{
  DDRB=0b00101000;
  PORTB=0b00100000;

defines the function for putting the first led on. The line DDRB=0b00101000; sets pin 3 and 5 in portB as outputs. The line PORTB=0b00100000 sets pin 5 of portB high hence putting on Led 1. In the main loop while 1() we call the different functions to turn on the desired led with a delay of 1 second.

Problems encountered and solutions

The board at first on programming issued no output . on checking the datasheet i realised one of the output pins used (pin 1) is the reset pin. I had to use the command rstdsbl command to turn the reset pin to an i/o pin. Even after getting output the leds did not blink in the desired sequence. i had to change their orientation several times.