My Father loves clocks and anything that reports the temperature (and other weather related info). So for Xmas 2010 I built this little piece to add to his collection.
It uses a DS1307 with backup battery to track time, and a LM35 for recording the temperature. The LCD displays time, date, current temperature and min and max recorded temperatures (which are backed up in EEPROM). The button at the bottom of the board is used to reset the min/max values. Also I included a serial connection so the sketch can be updated, and also a little serial protocol so the time can be adjusted if required. I used an iPod power supply for nice clean 5V supply - which I modded to use a 2-pin connector to attach to the board.
I also added a bunch of canned messages for specific dates, Xmas, NY, birthdays etc.
Finally presented it to him along with a laminated version of the schematic I created. He loved it!
Conn Funct Arduino ATmega328 Arduino Funct Conn
+-----\/----+
Reset 1| PC6 PC5 |28 D19 A5 SCL DS1307 SCL
FTDI Rx D0 2| PD0 PC4 |27 D18 A4 SDA DS1307 SDA
FTDI Tx D1 3| PD1 PC3 |26 D17 A3 LCD_RS
SQW Int0 D2 4| PD2 PC2 |25 D16 A2 LCD_E
Int1 D3 5| PD3 PC1 |24 D15 A1 LM35 GND REF
D4 6| PD4 PC0 |23 D14 A0 LM35 VO
7| VCC GND |22
8| GND AREF |21
Xtal 9| PB6 AVCC |20
Xtal 10| PB7 PB5 |19 D13 SCK RESET MIN/MAX
OC0B D5 11| PD5 PB4 |18 D12 MISO LCD_D4
OC0A D6 12| PD6 PB3 |17 D11 MOSI LCD_D5
D7 13| PD7 PB2 |16 D10 LCD_D6
D8 14| PB0 PB1 |15 D9 LCD_D7
+-----------+
DS1307 ATMega
+-----\/----+
Xtal 1| X1 VCC |8 VCC
Xtal 2| X2 SQW |7 D2/Int0
3V Bat 3| VBAT SCL |6 D19/SCL
GND 4| GND SDA |5 D18/SDA
+-----------+
FTDI 6-Pin Connector from top of board:
*-- RTS (GRN) --> 0.1uF cap --> PC6 (RESET)
*-- RX (YEL) --> TX
*-- TX (ORG) --> RX
*-- VCC (RED) --> VCC
*-- CTS (BRN) --> GND
*-- GND (BLK) --> GND
