•  read a microcontroller data sheet
•  program your board to do something,
  with as many different programming languages
  and programming environments as possible

• They are based on modified Harvard Architecture.
• They use the RISC instruction set, which allows lower CPU cycles per instruction.
• They have 8-bit memory addresses. (In the likes of Intel 808)
• They have flash on memory rather than EEPROM / one-time programmable / EPROM

• tinyAVR (ATtiny)
• megaAVR (ATmega)
• Xmega (ATxmega)

1. Embedded C
In my Hello World Board, I have connected LED to PIN6 i.e. PA7. So first step is to define PA7 as digital Output. We modify to the data direction register (DDR) for this.
The ATtiny 44 has 2 sets of these (PA and PB). For port A (PA0-PA7) we use the DDRA command.
To set all pins of PORT A as output we should write : DDRA =0xFF or DDRA =0b11111111. Where:
• "1" represents output.
• "0x" represents hexadecimal value
• "0b" represents binary value
To set any port as high we write PORTA |= (1<<7) or PORTA |= (0b10000000)
To set any port as low we write PORTA |= PORTA &= ~(1<<7) or PORTA &= ~(0b10000000)

/*
* led_blink.c
*
* Rohan Rege
*
*/

#define F_CPU 20000000 //Define clcok speed as 20Mhz
#include <avr/io.h> //Import header file required for AVR microcontrollers
#include <util/delay.h> //Import header flie required for delay function
int main(void)
{
DDRA = 0b10000000; //set PA7 as output
while (1) //Infinite Loop
{
PORTA |= (1<<7); // Set PA7 high (Make LED ON)
_delay_ms(5000); //delay of 5 sec
PORTA &= ~(1<<7); // Set PA7 low (Make LED OFF)
_delay_ms(5000); //delay of 5 sec
}
}



---


To flash this program, I've used Atmel Studio on windows.
Download and install atmel studio the go to file -> New -> Project



Then select the second option in GCC Executable Project C/C++



Then select the IC



Then copy the above program in the file



Save the file and click on build project
The output of the build should look like this



To program by the USB tiny we need to set it up.
To do that add it to the external devices of the atmel



Then build the again go to external tools and select the TINYUSB



This output looks like this:







---



2. Assembly

Assembly is a lower level language than Python and Embedded C.
Assembly language is an alphanumeric representation of machine code. Below is an example of a AVR assembly code written in assembly language. Each line of the code is an instruction telling the micro controller to carry out a task.


            ADD     R16, R17       ; Add value in R16 to value in R17
            DEC     R17            ; Minus 1 from the value contained in R17
            MOV     R18, R16       ; Copy the value in R16 to R18
END:        JMP     END            ; Jump to the label END



I have used the cbi and sbi to directly modify the registers.
The code is sourced from here

.device attiny44

.org 0
sbi DDRA,0

loop:
    sbi PORTA,0
    cbi PORTA,0
rjmp loop

I was going to try and follow the tutorial by Steven Chew to program IC in assembly.
But the it proved too challenging for me.
Also I could not justify the time required to program in assembly.

I'll not do anything that I don't understand hence I will not program this.



---



3. Arduino based C/C++

The arduino language is really great for beginners, but have some limitations (e.g. you must have all your files in the same folder). And it is basically a simplification of C/C++ (you can practically copy & paste arduino code to a C/C++ file, and it will work). Also it makes sense that you can go and use a full well known IDE as eclipse if you are experienced

/*

led_blink.ino

Rohan Rege

*/

void setup() {
 pinMode(PA7, OUTPUT);
}
void loop() {
 digitalWrite(PA7, HIGH);
 delay(300);
 digitalWrite(PA7, LOW);
 delay(300);
}


• Open the preferences dialog in the Arduino software.
• Find the “Additional Boards Manager URLs” field near the bottom of the dialog.
  
  
  
  
• Paste the following URL into the field (use a comma to separate it from any URLs you’ve already added):
  
  https://raw.githubusercontent.com/damellis/attiny/ide-1.6.x-boards-manager/package_damellis_attiny_index.json
  
  
• Click the OK button to save your updated preferences.
• Open the boards manager in the “Tools > Board” menu.
  
  
  
  
• Scroll to the bottom of the list; you should see an entry for “ATtiny”.
• Click on the ATtiny entry. An install button should appear. Click the install button.
• The word “installed” should now appear next to the title of the ATtiny entry.
  
  
  
  
• Close the boards manager. You should now see an entry for ATtiny in the “Tools > Board” menu.
  
  
  
  

• Arduino Pin 10: RESET
• Arduino Pin 11: MOSI
• Arduino Pin 12: MISO
• Arduino Pin 13: SCK

Put an LED (with resistor) on the following pins, its not necessary but helps to debug errors

• Arduino Pin 9: Heartbeat - shows the programmer is running
• Arduino Pin 8: Error - Lights up if something goes wrong (use red if that makes sense)
• Arduino Pin 7: Programming - In communication with the slave

Group Assignment:

• ARM11 has the ARMv6 Architecture, while ATtiny has AVR (modified Harvard architecture)
• ARM11 is more powerful when compared to AVR
• ARM11 is 32bit RISC, AVR is 8bit RISC
• The max memory that ARM11 can support is 4GB, it may less due to addressing. The max memory that AVR can support is 256KB
• Arm is more useful for microprocessing. AVR is more useful in microcontrolling
• In ARM, Flash, EEPROM, and SRAM might integrated onto a single chip, additional external memory can be added. In AVR, Flash, EEPROM, and SRAM are all integrated onto a single chip, removing the need for external memory in most applications
• Both can be programmed via Assembly language