wk8: 2016/03/16

The assignments for wk8 were as below;

1. Read a microcontroller data sheet
2. Program your board to do something, with as many different programming languages and programming environments as possible

This week, Prof. Niel directed us to read Datasheet: Microcontroller ATtiny44A to deepen the understanding on electrical production and embeded programming. I tried to understand the overview and major abbreviations on it since it had too many pages to read, 286pages of PDF!.

Datasheet: Microcontroller ATtiny44A

Overview

The one of most important information on datasheet is pin configurations, which shows below.

PIN configurations of ATtiny44A

To understand how I can handle the microcontroller and what its function is, I quickly summarize the definition of Abbreviation as below.

Abbreviation	explanation
VCC	Supply voltage.
GND	Ground
RESET	Reset input. A low level on this pin for longer than the minimum pulse length will generate a reset.
Port A	a 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit).
Port B	a 4-bit bi-directional I/O port with internal pull-up resistors (selected for each bit)
ADC	Analog to Digital Converter
AREF	External Analog Reference for ADC.
PCINT	Pin Change Interrupt source
AIN	Analog Comparator Positive Input.
T	Timer/Counter, counter source
USCK	Three-wire mode Universal Serial Interface Clock.
SCL	Two-wire mode Serial Clock for USI Two-wire mode.
DO	Data Output in USI Three-wire mode.
MISO	Master Data input, Slave Data output pin for SPI(Serial Peripheral Interface) channel.
OC	Output Compare Match output
XTAL	Chip Clock Oscillator
CLKI	Clock Input from an external clock source,
dW	debugWIRE
INT	External Interrupt Request
CKOUT	System Clock Output
ICP	Input Capture Pin
SDA	Two-wire mode Serial Interface Data.
MOSI	Master Data output, Slave Data input for SPI channel.
DI	Data Input in USI Three-wire mode.

Setting programming environments

Before starting programming, I had to prepare the environments of embeded programming. I had alredy installed Arduino IDE, so I installed FTDI driver, and added Attiny to Arduino IDE.

• Install Arduino IDE 1.6.5
• Add the Attiny to your board list in Arduino IDE
• Install the FTDI drivers

Checking the connection between the programmer and the board

Next, we have to check the conection between the programmer, this case USBtiny, and the board, this case "hello echo board". We can initialize the USBtiny, using the Linux commnad:
avrdude -c usbtiny -p t44
If the message is shown as below, you initialize the AVR device successfully and the connection is right. So now I finished preparation to write any programs to the board.

Initializing the usbtiny

Of course, you have to change the part of the commmand, especially t44, which is the part indicating the microcontroller, ATtiny44. You can refer the commands for otehr microcontrollers from this AVR Tutorial page.

Command list of each microcontrollers

Burning bootloader

We also had to run the "Burn Bootlooder", following Add the Attiny to your board list in Arduino IDE. To understand the Bootloader development, the website below was very useful.

• Arduino: Bootloader Development

For burning bootloder, the exact setting is as below;
This setting is really important if you use wrong setting, it will not work.

• Board: "ATtiny"
• Processor: "ATtiny44"
• Clock: "20MHz (external)"
• Programmer: "USBtinyISP"

Setting for burning bootlooder

Then, I run the bootloader on Arduino, and succeeded to run it as the screenshot below. According to Emma, our electrical instructor, we can run bootloader only once without mistakes, so I was seriously relieved when I can check the result.

Burning Bootlooder

Learning C language

Also, pure C is main programming language of Arduino, I quickly learned how to write C language using Dot Install: C Basic course, which is Japanese freemium programming learning support site because this is first time for me to write C though I used Ruby on my programming work.

Dot Install (for Japanese only)

Here I add the list of major codes on Arduino below;

C Code	explanation
int	Show the working tree status
byte	Show the working tree status
print	Show the working tree status
serial	Show the working tree status

Blinking test

First, I tried very simple blinking test, which was the simplest one from Arduino library, to see correct correspondence between pin number of Arduino and those of hello echo board.

To identify the correspondings, the web page below was very useful.

• Fab Academy Tutorial: ATtiny Embedded Programming with the Arduino IDE

There is a table of correspondings, so that I could quickly identify it as the table below.

ATtiny 44A vs. Arduino Pin-Out Numbering

Then, I referred the schematic of hello-echo board, and found that the pin connected to LED was pin7 on Arduio.

Schematic of hello-echo board

The code as below is the first test one, which is very simple blinking program.

20160317_blink_test.ino

int pin_number = 7;

void setup() {
  pinMode(pin_number, OUTPUT);
}

void loop() {
  digitalWrite(pin_number, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);              // wait for a second
  digitalWrite(pin_number, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);              // wait for a second
}

Next, I would like to test the attribute of PWM, then I wrote the code as below. Regarding the PWM, Arduino: PWM is very easy to udnerstand.

20160317_blink_test_v2.ino

int pin_number = 7;

void setup() {
  pinMode(pin_number, OUTPUT);
}

void loop() {
  analogWrite(pin_number, 255);   // turn the LED on (HIGH is the voltage level)
  delay(500);              // wait for a second
  analogWrite(pin_number, 200);    // turn the LED off by making the voltage LOW
  delay(500);              // wait for a second
  analogWrite(pin_number, 150);    // turn the LED off by making the voltage LOW
  delay(500);              // wait for a second
  analogWrite(pin_number, 100);    // turn the LED off by making the voltage LOW
  delay(500);              // wait for a second
  analogWrite(pin_number, 50);    // turn the LED off by making the voltage LOW
  delay(500);              // wait for a second  
}

Then, you can see the result of implementation from the video below.

Blinking test

Next, I would like to try simle if sentense on Arduino, so I wrote the simple code reading the status of switch and turing light on/off accordingly.

20160317_blink_test_v3.ino

int led_pin = 7;
int sw_pin = 3;

int sw = 1;

void setup() {
  pinMode(led_pin, OUTPUT);
  pinMode(sw_pin, INPUT);  
}

void loop() {
  sw = digitalRead(sw_pin);

  if (sw == HIGH) {
    digitalWrite(led_pin, HIGH);
  }
  else {
    digitalWrite(led_pin, LOW);
  }
}

Hello World Test

Next, I tried serial connection using FTDI cable, which I bought with other menbers. Regarding the difference between serial communication and parallel communication, I learned from this page: sparkfun - Serial Communication.

Pin configurations of FTDI cable

I wrote the code below and successfully run the program in the end though at first I was struggling to try run the serial communication with FabTinyISP connected to my laptop...

Hello-echo board connected by FTDI cable

20160317_hello_world.ino

#include 
#define pin_rx 0
#define pin_tx 1

SoftwareSerial serial(pin_rx, pin_tx);

int sw_pin = 3;
int sw_value = 0;

void setup() {
 serial.begin(9600);
 pinMode(sw_pin, INPUT);
}

void loop() {
 sw_value = digitalRead(sw_pin);
 serial.println("hello World");
 delay(1000);
}

Though I would like to try the other programming languages and environments, and further complex programming, the time was up. The result of hello world programming is as the video below.

"Hello world" on serial communication