Email clock

Email Clock - Version 2

For the second version of the email clock, I wanted to simplify the networking aspect of it. I also wanted to make a prettier clock. So I changed technologies. For the controller, I used an Arduino module, which is an open source microcontroller module based on Atmel's ATmega8 microcontroller. For the net connection, I used a Lantronix Xport serial-to-ethernet module. And for the mail client, I wrote a perl script.

The wiring between the Arduino module and the Xport was simple: Arduino serial receive connects to the Xport's serial send, and vice versa. I also connected LEDs to some of the Arduino pins to use as indicators for debugging. You can see in the code below when I was using LEDs to figure things out.

To connect the Xport to the Arduino module, I designed an Ardduino shield printed circuit board (PCB). I designed it in Eagle, a great shareware schematic and board layout program. Cadsoft have a great tutorial on the site, if you've never made a PCB. Here's the board schematic:

And here's a picture of the board layout:

And here's a link to the Eagle files. To get the board manufactured, I recommend sending the gerber files to Advanced Circuits or Sparkfun. Advanced Circuits is a bit more expensive, but they've got a good circuit checking service online, FreeDFM. Sparkfun's a bit slower, but their rates are lower, and they're great people.

Here's a parts list for the board:

Part	Value	Part No.	Comments
C1	10uF	Digikey P828-ND	Any polarized 10uF capacitor will do.
C2	1.0uF	Digikey 478-1836-ND	Any polarized 1.0uF capacitor will do.
C3	1.0uF	Digikey 478-1836-ND	Any polarized 1.0uF capacitor will do.
D6	1N5817	Newark 48F6702 Digikey,1N5817DICT-ND	This keeps the 3.3V regulator from overheating. DO-41 package
IC1	MIC2915033-BU	Newark 83F5900	Make sure to use the the BU model, which is a surface-mount (TO-263) package. The two different packages help differentiate the 5V regulator from the 3.3V regulator.
ICSP	Pin Headers	Digikey 929974-01-08-ND	These are female headers, straight. I use male headers to hold them to the Arduino's female headers, with the male headers sandwiched in between the two boards.
J1	Pin Headers	Digikey 929974-01-08-ND	These are female headers, straight. I use male headers to hold them to the Arduino's female headers, with the male headers sandwiched in between the two boards.
J2	Pin Headers	Digikey 929974-01-0-ND	These are female headers, straight. I use male headers to hold them to the Arduino's female headers, with the male headers sandwiched in between the two boards.
J3	Pin Headers	Digikey 929974-01-08-ND	These are female headers, straight. I use male headers to hold them to the Arduino's female headers, with the male headers sandwiched in between the two boards.
LED1	LED	Digikey 160-1144-ND	Green LED
LED2	LED	Digikey 160-1144-ND	Green LED
LED3	LED	Digikey 160-1144-ND	Green LED
LED4	LED	Digikey 160-1144-ND	Green LED
LED5	LED	Digikey 160-1144-ND	Green LED
LED6	LED	Digikey 160-1144-ND	Green LED
R1	10K	Newark 84N2322 Digikey 10KQBK-ND	Goes with the reset switch. 0207/10 package
R2	220 Ohm	Digikey 220QBK-ND	Goes with LED. 0207/10 package
R3	220 Ohm	Digikey 220QBK-ND	Goes with LED. 0207/10 package
R4	220 Ohm	Digikey 220QBK-ND	Goes with LED. 0207/10 package
R5	220 Ohm	Digikey 220QBK-ND	Goes with LED. 0207/10 package
R6	220 Ohm	Digikey 220QBK-ND	Goes with LED. 0207/10 package
R7	1.0K	Digikey 1.0KQBK-ND	Goes with reset switch. 0207/10 package.
R8	220 Ohm	Digikey 220QBK-ND	Goes with LED. 0207/10 package
S1	Reset switch	Digikey SW400-ND	Reset switch
CON1	X-PORT	Symmetry XP1002000-03	I get mine from Symmetry, but you can also get them from GridConnect (thanks to Jeff Gray for the link)

The system works like this: The Arduino opens a TCP socket to port 80 on the CGI server every few seconds. It makes a HTTP call for the CGI script. The script checks all my mail accounts, and returns the number of kilobytes. The clock then ticks forward one tick for every kilobyte of mail.

Here's the Arduino code for the microcontroller, and here's the CGI script.