DS1307 Utility Copyright (C) 2005 by Donald R. Blake donblake at worldnet.att.net This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. This project demonstrates the use of the Dallas Semiconductor DS1307 64x8 Serial Real Time Clock. Address and data information are transferred to the DS1307 via a Two-wire Serial Interface (TWI). This project provides the means for controlling and viewing the DS1307 settings via an RS232 interface. The data sheet for the DS1307 is available here: http://pdfserv.maxim-ic.com/en/ds/DS1307.pdf I'm using a DS1307 module from Spark Fun Electronics. Go to the Spark Fun web page at: http://www.sparkfun.com and search for Comp-RTC. This project runs on an ATmega32 using a 7.3728 MHz crystal. It has also been tested on an ATmega8. It will probably compile and work for any AVR that has TWI and a hardware UART. You may need to change MCU and F_CPU in the makefile. Connect the AVR UART to a PC serial port through a device like the MAX232, ST232, etc. I run Tera Term (Pro) on the PC side. You can obtain Tera Term (Pro) from: http://hp.vector.co.jp/authors/VA002416/teraterm.html The program responds to ASCII commands typed by the user. Here is the list of commands: ? Show time, date and day of week. thh:mm:ss Set time to HH:MM:SS in 24-hour mode. thh:mm:ssa Set time to HH:MM:SS AM in 12-hour mode. thh:mm:ssp Set time to HH:MM:SS PM in 12-hour mode. dyy-mm-dd Set date to YY-MM-DD. YY is the year (0..99), MM is the month (1..12) and DD is the day (0..31, depending on the month). yd Set day of week to D (1..7). o0 or o1 Set the SQW/OUT pin to a logic 0 or logic 1 level. s0, s1, s2 or s3 Set the SQW/OUT pin to a squarewave output. The SQW/OUT frequency is: 1 Hz for s0, 4.096kHz for s1, 8.192kHz for s2 and 32.768kHz for s3. h Help - show list of commands. Enter just the command character with no parameters for usage.