Week 08 : Embedded programming

Individual assignment

For this Assignment we first worked with the Arduino and the whole assignment was for the Arduino the datasheet reading, the features, etc.. and after finishing the whole Assignment, and since we already milled our Hello boards we had to redo everything.

Read a microcontroller datasheet:The Attiny24/44/84

What's more challenging was "reading" the datasheet! And I got to say, it's totally not that easy to read it.

The Atmel® ATtiny24/44/84 is a low-power CMOS 8-bit microcontroller based on the AVR enhanced RISC architecture. By executing powerful instructions in a single clock cycle, the Atmel ATtiny24/44/84 achieves throughputs approaching 1MIPS per MHz allowing the system designer to optimize power consumption versus processing speed.

ATtiny24/44/84 DATASHEET

ATtiny24/44/84 Features

The Atmel ATtiny24/44/84 provides the following features:

2/4/8K bytes of in-system programmable flash

128/256/512 bytes EEPROM

128/256/512 bytes SRAM

12 general purpose I/O lines

32 general purpose working registers

an 8-bit Timer/Counter with two PWM channels

a 16-bit Timer/Counter with two PWM channels

internal and external interrupts

an 8-channel 10-bit ADC

programmable gain stage (1x, 20x) for 12 differential ADC channel pairs

a programmable watchdog timer with internal oscillator

internal calibrated oscillator

and three software selectable power saving modes.

Pinout Schematic

Through DATASHEETs we get to know more about the functions associated with the pins. It has to be known in order to be used wisely.

• VCC is a digital voltage supply.
• GND denotes Ground and it has a 0V.
• GND denotes Ground and it has a 0V.
• RESET
• Port B (PB3...PB0) Port B also serves the functions of various special features of the Atmel ATtiny24/44/84.
• Port A Port A has an alternate function as analog input for the ADC, analog comparator, Timer/Counter, SPI and pin change interrupt.

The Architecture

The ATTINY44 runs with the RISC Architecture. RISC or reduced instruction set computer is a computer which only uses simple commands that can be divided into several instructions which achieve low-level operation within a single CLK cycle, as its name proposes “Reduced Instruction Set”. It's performance is optimized with more focus on software. RISC mainly Used in Microcontroller.
The Block Diagram for the ATTINY44, according to the datasheet has four main sections:

Block diagram shows the internal circuitry and the programflow

The Atmel ATtiny24/44/84 Memory

The Atmel ATtiny24/44/84 contains 2/4/8K bytes of on-chip, in-system, reprogrammable flash memory for program storage. Since all AVR instructions are 16 or 32 bits wide, the flash memory is organized as 1024/2048/4096 x 16.

Using the Arduino App to Program our boards

Arduino is a single-board microcontroller meant to make the application more accessible which are interactive objects and its surroundings. The hardware features with an open-source hardware board designed around an 8-bit Atmel AVR microcontroller or a 32-bit Atmel ARM. Current models consists a USB interface, 6 analog input pins and 14 digital I/O pins that allows the user to attach various extension boards.

The Arduino Uno board is a microcontroller based on the ATmega328.

Getting started

You can download the Arduino software and get started with it.

Since I'm new to this, I just followed online instructions

Here's some instructions on what to do after downloading the Arduino software!
• Then comes the ‘print’ option and ‘preferences’. When you will click on ‘Preference’ option:


This window will open and it will be showing sketckbook location, the language used here, the size of witing, etc..

• The icon numbered a ‘1’ is of ‘verify’.
• The icon numbered as ‘2’ is to upload the sketch into your micro controller.
• The icon numbered as ‘3’ is of ‘New’.
• The icon numbered as ‘4’ is of ‘open’.
• The icon numbered as ‘5’ is of ‘save’.

After downloading the software now it's time for uploading the code by clicking on the icon '2'.

For the wiring I did the same thing as in the 6th week except for that, the arduino code is so simple, it's to make the LED of the board to blink every 5 seconds.

int buttonState = 0;
void setup() {
  // initialize digital pin LED_BUILTIN as an output.
  pinMode(7, OUTPUT);
}

// the loop function runs over and over again forever
void loop() {
  digitalWrite(7, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(5000);                       // wait for a 5 seconds
  digitalWrite(7, LOW);    // turn the LED off by making the voltage LOW
  delay(5000);                       // wait for a 5 seconds
}

And this is how it turned out

I tried another code to control the blinking of the led with the pushbutton
For this part, I used another programmer from a previous WEEK: my FabISP

// constants to define where led and button are connected:
const int BUTTON_PIN = 3; // the pushbutton pin
const int LED_PIN = 7; //  the LED pin
// variables will change:
int buttonState = 0; // variable for reading the pushbutton status
void setup() {
// initialize the LED pin as an output:
pinMode(LED_PIN, OUTPUT);
// initialize the pushbutton pin as an pull-up input:
// the pull-up input pin will be HIGH when the switch is open and LOW when the switch is closed.
pinMode(BUTTON_PIN, INPUT_PULLUP);
}
void loop() {
// read the state of the pushbutton value:
buttonState = digitalRead(BUTTON_PIN);// control LED according to the state of button
if(buttonState == LOW) // If button is pressing
digitalWrite(LED_PIN, HIGH); // turn on LED
else // otherwise, button is not pressing
digitalWrite(LED_PIN, LOW); // turn off LED
}

To have a quick understanding of the port manipulation in the C code check this

Note: "1" represents output. "0x" represents hexadecimal value & "0b" represents binary value

To set all pins of PORT A as input we should write : DDRA =0x00 or DDRA =0b00000000 "0" represents input.

To set PA7 as output & PA3 as input we should write : DDRA =0x80 or DDRA =0b10000000

To set a particular pin high or low, we use PORT command.

Few examples for using PORT command are given below:

To make pin 7 of PORT A high (i.e. 1) we should write : PORTA |= (1<<7) or PORTA |= (0b10000000)

Note: "|" represents boolean OR operator. "<<" represents left shift operator. So the 7the digit of the port will become 1 and all other pins will remain the same. It's because if we boolean OR something with 1 the result will be 1 and if we boolear OR something with 0 the result will be the same thing.

To make pin 7 of PORT A low (i.e. 0) we should write : &= ~(1<<7) or PORTA &= ~(0b10000000)

Note: "&" represents boolean AND operator. "~" represents negation operator. Here the 7the digit of the port a will become 0 and all other pins will remain the same. This is because if we boolean AND something with 0 the result will be 0 and if we boolear AND something with 1 the result will be the same thing.
Note: (1<<3) means 1(i.e 0b00000001) will be rotated three times towards left.
For more Infos, check this one
For this code it's the direct translation of the Arduino code, so in short is going to make the LED blinks every 3 seconds!

#include <ArduinoJson.h>
#include <avr/io.h>
#include <util/delay.h>
#define F_CPU 8000000  //Define clcok speed as 1Mhz

int main(void)
{
  DDRA = 0b10000000;  //set PA7as output & all other pins as input  
    while (1) //Repeat the below actions continuously
    {
    PORTA |= (1<<7);// Set PA7 high (Make LED ON)
    _delay_ms(3000);//delay of 3 sec
    PORTA &= ~(1<<7);// Set PA7 low (Make LED OFF)
    _delay_ms(3000);//delay of 3 sec
  }
}

Using ARDUINO UNO as a Programmer


Using FabISP as a Programmer

Group Assignment

For this part of , here's the direct linkfor the assignment

For this Assignment we've been told to campare the performance and developement workflows for other architectures