AVRSpike/AVRNotes at master · mstaffeld/AVRSpike · GitHub

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Be Familiar With:
- Hexidecimal and Binary
- Logic Unary, (And, Or, Not, Xor)
- Registers
- ADC
- Baud Rates
- Timers
- .hex (The machine code the mircrocontroller will use.)
- PORT (Ports are usually groups of pins, sometimes 8 pins)
- bitwise shift operators (>> right shift, << left shift)
- bitwise or operator (| pipe)
- Resistors, bits
- Microcontroller architecture, memory layout, hardware layout
- assembly

Education Journey:

Learnings from AVR C Basics:
https://www.youtube.com/watch?v=024f0NX2FLs

| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |

myVariable = 0b00000001 << 2
myVariable becomes 0b00000100

Hexidecimal to binary
Binary to Hexidecimal

Hexidecimal: 0x01
Binary: 0000 0000 0000 0001

We will set PORTA by OR if there is an existing bit
This:
```
PORTA = PORTA | (0x01 << 2)
```
Becomes:
```
PORTA |= (0x01 << 2)
```

Resistors (have names, and bits have names):
Name: DDRA
Bits: DDA7 | DDA 6 | DDA 5 | DDA4 | DDA3 | DDA2 | DDA1 | DDA0

# Clearing a bit:
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| 1 | 0 | 1 | 0 | 1 | 0 | 1 | 0 |

Let's clear the bit at position 1 and keep existing other values.

PORTA is 10101010
Get a new (0x01) (0b00000001)
Shift the first bit to the left, once (0x01 << 1):
Result: (0b00000010)
Now invert the new shifted hex ~(0x01 << 1):
Result: (0b11111101)
Now, & the existing PORTA values with the new shifted hex PORTA &= ~(0x01 << 1)

PORTA &= ~(0x01<<1)

~ - is the bitwise not operator, bitwise invert operator
& - is the and operator, if 0 & 0 = 0, if 1 & 0 = 0, if 1 & 1 = 1

C-Code Time:
```

```

# Data Types

RAM Matters since there is only a little bit.
Be careful in defining data types.

Common Data Types:
- Unsigned char (8 bits, 1 byte, (2^8-1), 0 - 255 decimal)
    Meant to store ASCII characters
```
    unsigned char myLetter = 'A';
    unsigned char myNumber = 200;
    unsigned char myLetterHex = 0xFF;
    unsigned char myLetterBin = 0b00010001;

```
-

# Data Structures


# c printf
https://www.tutorialspoint.com/c_standard_library/c_function_printf.htm


Todo:

Instead of using the bit position, you can use the bit name.


# Need to still learn
- How to mock, drive the avr stuff without pushing to hardware
- How to debug even the basics
- Really understand Hexadecimal and binary conversion (write the conversion util)
- avc-gcc compiles c to assembly, then the hex file
- memory


DDRx is the data direction register - in or out
PORTx is the state of the pin - on or off

DDRB - B port
0000 0001

PORTB -
0000 0000 - off
0000 0001 - on