Quozl's PIC 16F877 Uptime

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A program for a PIC 16F877 microcontroller with a 2x16 line LCD panel that shows the number of days, hours, minutes and seconds since reset.

The program continues the work on the FSR data stack architecture, providing functions for LCD panel, vectored execution and base conversion and then placing them into a working example.

Program Outline

uses TMR0 at 1:256 prescale at 4MHz with interrupts as the source of the 1Hz time source,
interrupt service routine increments time and sets a flag which is monitored by a main function,
main function waits for flag to be set, fetches the counter with an interlock, and then displays it on the LCD.

Design Goals

minimal use of file registers,
execution speed not an issue,
construction of reusable peripheral modules,

Program Source

uptime.asm main program,
stack.inc data stack macros,
stack.asm data stack functions,
table.asm table handling and vector execution functions,
lcd.asm LCD panel functions
bcd.asm decimal conversion functions
hex.asm hexadecimal conversion functions
p16f877.inc processor register definitions

Hardware

This project was built on a Dontronics DT106A PCB, using a PIC 16F877 and a 4MHz crystal. I didn't make a schematic diagram, but worked to Don's schematic. If you wish to recreate this device, see Don's page for the DT106, at http://dontronics.com/dt106.html, he has schematics and assembly instructions. I made no significant modifications to his hardware.

Change Log

Date	Change
2002-04-17	Add hardware section due to popular demand.
2001-03-05	Initial page.

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