AVR245: Code Lock with 4x4 Keypad and I2C(TM) LCD Documentation

Atmel AVR Application Note

Introduction

This documents functions, variables, typedefs, enumerations, enumerator and defines in the software for application note AVR245. This is a Code lock application, which uses a 4x4 keypad matrix, piezoelectric buzzer and I2C LCD..

Compilation Info

This software was written for IAR Embedded Workbench, 4.11A.
To make project: Add the .c files to project (main.c, KPD.c, LCD.c and USI_TWI_Master.c) and use project settings: device tiny24, enable bit definitions in I/O include files, output format: ubrof8 for Debug and intel_extended for Release.
Please also note that iotiny24.h included with EWAVR 4.11A has wrong address for TIMSK0; it is 39 not 3A. The timer interrupt names may also change in the next version of EWAVR.

Add to Release target: Linker - Extra Options - Use the following command line options:
-y(CODE)
-Ointel-extended,(XDATA)=$PROJ_DIR$\Release\Exe\$PROJ_FNAME$_eeprom.hex
This generates a separate file for the eeprom data to overcome limitations in the intel extended format.

Older versions than IAR Embedded Workbench 4.11A doesn't natively support ATtiny24.

Device Info

This example is written for the ATtiny24, but can be easily migrated to other AVRs.
Device settings: 1 MHz clock (internal RC).

Code Size:

1607 bytes (IAR 4.11A, maximum optimization).

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