https://github.com/mytechnotalent/atmega328p_io_driver
An ATmega328P IO driver written entirely in Assembler.
https://github.com/mytechnotalent/atmega328p_io_driver
arduino arduino-nano arduino-platform arduino-programming arduino-project assembler assembly atmega328p avr avr-programming avrdude input-output
Last synced: 9 days ago
JSON representation
An ATmega328P IO driver written entirely in Assembler.
- Host: GitHub
- URL: https://github.com/mytechnotalent/atmega328p_io_driver
- Owner: mytechnotalent
- License: apache-2.0
- Created: 2025-01-15T00:28:04.000Z (6 months ago)
- Default Branch: main
- Last Pushed: 2025-06-08T21:36:13.000Z (about 1 month ago)
- Last Synced: 2025-06-08T22:20:55.877Z (about 1 month ago)
- Topics: arduino, arduino-nano, arduino-platform, arduino-programming, arduino-project, assembler, assembly, atmega328p, avr, avr-programming, avrdude, input-output
- Language: Assembly
- Homepage:
- Size: 1.71 MB
- Stars: 2
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
## FREE Reverse Engineering Self-Study Course [HERE](https://github.com/mytechnotalent/Reverse-Engineering-Tutorial)
# ATmega328P IO Driver
An ATmega328P IO driver written entirely in Assembler.
# Code
```assembler
; ===================================================================
; Project: ATmega328P IO Driver
; ===================================================================
; Author: Kevin Thomas
; E-Mail: [email protected]
; Version: 1.0
; Date: 12/27/24
; Target Device: ATmega328P (Arduino Nano)
; Clock Frequency: 16 MHz
; Toolchain: AVR-AS, AVRDUDE
; License: Apache License 2.0
; Description: This program is a simple I/O to which when a button
; connected to PD2 is pressed, an external LED connected
; to PD4 will illuminate, otherwise it will be off.
; ===================================================================
; ===================================================================
; SYMBOLIC DEFINITIONS
; ===================================================================
.equ DDRD, 0x0A ; Data Direction Register for PORTD
.equ PORTD, 0x0B ; PORTD Data Register
.equ PIND, 0x09 ; Input Pins Address for PORTD
.equ PD2, 2 ; Pin 2 of PORTD (D2 on Nano)
.equ PD4, 4 ; Pin 4 of PORTD (D4 on Nano)
; ===================================================================
; PROGRAM ENTRY POINT
; ===================================================================
.global program ; global label; make avail external
.section .text ; start of the .text (code) section
; ===================================================================
; PROGRAM LOOP
; ===================================================================
; Description: Main program loop which executes all subroutines and
; then repeads indefinately.
; -------------------------------------------------------------------
; Instructions: AVR Instruction Set Manual
; 6.87 RCALL – Relative Call to Subroutine
; 6.90 RJMP – Relative Jump
; ===================================================================
program:
RCALL Config_Pins ; config pins
program_loop:
RCALL Check_Button ; check button state; control LED
RJMP program_loop ; infinite loop
; ===================================================================
; SUBROUTINE: Config_Pins
; ===================================================================
; Description: Main configuration of pins on the ATmega128P Arduino
; Nano.
; -------------------------------------------------------------------
; Instructions: AVR Instruction Set Manual
; 6.33 CBI – Clear Bit in I/O Register
; 6.95 SBI – Set Bit in I/O Register
; 6.88 RET – Return from Subroutine
; ===================================================================
Config_Pins:
CBI DDRD, PD2 ; set PD2 as input (button pin)
SBI PORTD, PD2 ; enable pull-up resistor on PD2
SBI DDRD, PD4 ; set PD4 as output (LED pin)
RET ; return from subroutine
; ===================================================================
; SUBROUTINE: Check_Button
; ===================================================================
; Description: Checks if PD2 is pressed and if so, drive LED high,
; otherwise drive LED low.
; -------------------------------------------------------------------
; Instructions: AVR Instruction Set Manual
; 6.97 SBIS – Skip if Bit in I/O Register is Set
; 6.96 SBIC – Skip if Bit in I/O Register is Cleared
; 6.88 RET – Return from Subroutine
; ===================================================================
Check_Button:
SBIS PIND, PD2 ; skip next inst if PD2 is high
RCALL LED_On ; if PD2 is low; BTN pressed
SBIC PIND, PD2 ; skip next inst if PD2 is low
RCALL LED_Off ; if PD2 is high; BTN not pressed
RET ; return from subroutine
; ===================================================================
; SUBROUTINE: LED_On
; ===================================================================
; Description: Sets PB5 high to turn on the LED.
; -------------------------------------------------------------------
; Instructions: AVR Instruction Set Manual
; 6.95 SBI – Set Bit in I/O Register
; 6.88 RET – Return from Subroutine
; ===================================================================
Led_On:
SBI PORTD, PD4 ; set PD4 high
RET ; return from subroutine
; ===================================================================
; SUBROUTINE: LED_Off
; ===================================================================
; Description: Clears PB5 to turn off the LED.
; -------------------------------------------------------------------
; Instructions: AVR Instruction Set Manual
; 6.33 CBI – Clear Bit in I/O Register
; 6.88 RET – Return from Subroutine
; ===================================================================
Led_Off:
CBI PORTD, PD4 ; set PD4 low
RET ; return from subroutine
```
## License
[Apache License 2.0](https://github.com/mytechnotalent/ATmega328P_IO_Driver/blob/main/LICENSE)