# Registers

!!! Attention
     resistor[ruh_**zi**_str] : [electrical component that implements electrical resistance](https://en.wikipedia.org/wiki/Resistor#:~:text=A%20resistor%20is%20a%20passive,transmission%20lines%2C%20among%20other%20uses.)    
     register[**reh**_juh_str] : [a memory location within the actual processor that work at very fast speeds](https://computersciencewiki.org/index.php/Registers_within_the_CPU)

## n-ary numbers

- 1 byte = 8 bits = 2^8 = 256 = [7:0]
- 1 B = 8 b


    JP   | EN        | usable  |15       |255|255
    --   |---        |-- |--       |-- |--
    2進数 |Binary     |0,1|0b1111  |0b11111111|B11111111
    10進数|Decimal    |0,1,2,3,4,5,6,7,8,9|0d15　　　|0d255|255
    16進数|Hexadecimal|0,1,2,3,4,5,6,7,8,9,</br>A,B,C,D,E,F|0xf|0xff|$f

- Ref. [2進数、8進数、10進数、16進数相互変換ツール](https://hogehoge.tk/tool/number.html)


!!! Note
    1**k**B = 1 [kilo] byte = 1000 B  
    1**K**B = 1 [ke̞ː] byte = 1024 B = 2^10 B = 1KiB = 1 [kibi] byte  

    1 bps = 1 [bits per second]  


## pinout
![](../images/register/ATtiny_x14.gif)

## Datasheet

[ATtiny1614](http://ww1.microchip.com/downloads/en/DeviceDoc/ATtiny1614-16-17-DataSheet-DS40002204A.pdf)


5.　I/O Multiplexing and Considerations  
5.1 Multiplexed Signals  

![](../images/register/PORT_Function _Multiplexing .png)

> Pin names are of type Pxn, with x being the PORT instance (A, B) and n the pin number. T``


16 .  PORT - I/O Pin Configuration  
16.1 Features  
 General Purpose Input and Output Pins with Individual Configuration:    
 – Pull-up


16.2 Overview

> The I/O pins of the device are controlled by instances of the PORT peripheral registers. **Each PORT instance has up to eight I/O pins. The PORTs are named PORTA, PORTB, PORTC, etc.**
>  
> **Each PORT pin has a corresponding bit in the Data Direction (PORTx.DIR) and Data Output Value (PORTx.OUT)** registers to enable that pin as an output and to define the output state. For example, **pin PA3 is controlled by DIR[3]
and OUT[3] of the PORTA instance.**



16.4 Register Summary - PORTx
![](../images/register/Register_Summary-PORTx.png)

16.5.1 Data Direction

> Name: DIR  
> This bit field controls the output driver for each PORTx pin.

Value |Description
:--:|:--
0 |Pxn is configured as an input-only pin, and the output driver is disabled
1 |Pxn is configured as an output pin, and the output driver is enabled


16.5.5 Output Value

> Name: OUT  
> This bit field controls the output driver level for each PORTx pin.

Value |Description
:--:|:--
0 |The pin n (Pxn) output is driven low  
1 |The Pxn output is driven high

16.5.9 Input Value

> Name: IN  
> This bit field shows the state of the PORTx pins when the digital input buffer is enabled

Value |Description
:--:|:--
0 |The voltage level on Pxn is low
1 |The voltage level on Pxn is high



## Program

Arduio Sketch

```
void setup() {
  pinMode(8, OUTPUT);
}
void loop() {
  digitalWrite(8,HIGH);
  delay(500);
  digitalWrite(8,LOW);
  delay(500);
}
```
AVR 1-series (1614)
```
void setup() {
  PORTA.DIR |= 0b00000001;//ポートAの0番ピン(Arduinoの11番ピン)をOUTPUT
}
void loop() {
  PORTA.OUT |= 0b00000001;//ポートAの0番ピン(Arduinoの11番ピン)をHIGH
  delay(500);
  PORTA.OUT &= ~0b00000001;//ポートAの0番ピン(Arduinoの11番ピン)をLOW
  delay(500);
}
```

AVR
```
void setup() {
  DDRB |= 0b00000001;//ポートBの0番ピン(Arduinoのn番ピン)をOUTPUT
}
void loop() {
  PORTB |= 0b00000001;//ポートBの0番ピン(Arduinoのn番ピン)をHIGH
  delay(500);
  PORTB &= ~0b00000001;//ポートBの0番ピン(Arduinoのn番ピン)をLOW
  delay(500);
}
```

Ref. [Arduinoで入出力を高速化する方法](https://haizairenmei.com/2019/11/29/avr/)

!!! HINT

    **代入**  
    a = 0; //初期値 代入    
    b = a + 1; //代入   
    a = a + 1; //加算代入  
    a += a; //加算代入

    **OR**  
    PORTB.DIR = 0b00000001; //初期値  
    PORTB.DIR = PORTB.DIR | 0b00010000 //OR  
    PORTB.DIR **|=** 0b00010000 //OR  

<!-
    DDRB = 0b000000; //初期値  
    DDRB = DDRB | 0b00000001; //OR  
    DDRB |= 0b00000001; //OR  
->

## Bitwise Operators (bit演算子)

機能|演算子|使用例
--  |--    |--   
OR	|``|`` |指定bitのセット
AND |&	   |指定bitの取り出し, NOTと併用した指定bitのクリア
XOR |	^	   |bit反転
NOT |	~	   |bit反転, bitクリア
ビットシフト(右)|	>>	|ビットシフト
ビットシフト(左)|	<<	|ビットシフト

!!! Note
    operand: 被演算子


### OR  
```
0  0  1  1    operand1
0  1  0  1    operand2
----------
0  1  1  1    (operand1 | operand2) - returned result
```
1に指定したbitは、元が0でも1でも、1になる  -> 指定bitのセット  

### NOT  
```
0  1    operand1
-----
1  0   ~operand1
```
1に指定したbitは、0に反転する (0は1に反転する)

### AND  
```
0  0  1  1    operand1
0  1  0  1    operand2
----------
0  0  0  1    (operand1 & operand2) - returned result
```
NOTで反転した0に指定したbitは、元が0でも1でも、0になる  -> 指定bitのクリア  

ref. [Arduino Language Reference](https://www.arduino.cc/reference/en/)

## Example

```
void setup() {
  PORTA.DIR |= 0b00010001; //Set PA4 and PA0 to OUTPUT
}

void loop() {
  PORTA.OUT |= 0b00000001;  //Set PA0 to HIGH...(1)
  delay(500);
  PORTA.OUT |= 0b00010000;  //Set PA4 to HIGH...(2)
  delay(500);
  PORTA.OUT &= ~0b00000001; //Set PA0 to LOW....(3)
}
```
### What to work in (1)(2)(3)

```
(1) OR
0000 0000   operand1_1
0000 0001   operand1_2
---------
0000 0001   (operand1_1 | operand1_2) - returned result1

(2) OR
0000 0001   operand2_1 (returned result1)
0001 0000   operand2_2
---------
0001 0001   (operand2_1 | operand2_2) - returned result2

(3)
(3-1) NOT
0000 0001   operand3_1
---------
1111 1110   ~operand3_1

(3-2) AND
0001 0001   ~operand3_2 (returned result2)
1111 1110   operand3_1
---------
0001 0000   (~operand3_1 & operand3_2) - returned result3

```