The Parts<\/strong><\/p>\n The Ethernet shield connected to the Arduino,and an FSR connects to analog input 0 using a voltage divider circuit:<\/p>\n Here are some photos of the module under the test bed, thanks to Diego: <\/a> Before coding, I had to learn a little about Pachube. \u00a0Their tutorials<\/a> are very good, so all I needed was the Quickstart Guide.<\/a> I set up a feed that’s a manual feed type, meaning I upload data when I want to. My feed has just one value, for the sensor.<\/p>\n From there, I learned that if I have my feed’s address, I can to make an HTTP PUT call with the sensor value as the content (comma-separated if there’s more than one value) that looks like this:<\/p>\n The content-length field is a count of every character in the content, which is the line at the very end. \u00a0Content always comes after two newlines, at the end a HTTP PUT request<\/a>, as shown above. If I was planning to send only one sensor, my PUT statement would look more like this:<\/p>\n Using the Ethernet shield, that kind of a call is trivial. It’s just a series of print statements, like so:<\/p>\n My Arduino program starts with the usual including of the libraries I need (in this case the Ethernet library) and setting global variables. I have one to hold the instance of the Ethernet library, one to keep track of the last connection time, and one to keep track of whether I was connected last time through the main loop:<\/p>\n The setup just initializes the Ethernet client and the serial library:<\/p>\n The main loop starts by reading the sensor. Then it checks for any incoming bytes from the server, and printing them out. I used this for debugging only. Once the code is working, you don’t need to see the server’s response.<\/p>\n Next, I check to see if the server’s dropped the connection since the last time the main loop ran. if so, I stop the client:<\/p>\n Pachube’s quickstart guide makes it clear that you can’t upload data more than once every five seconds, so I wrote a main loop that keeps track of when the last time it connected was, and only connects if it’s not currently connected, and if more than ten seconds have passed, like so:<\/p>\n That’s it for the main loop. The only other method I needed was a routine to calculate the content length. The sensor’s value is the content length, and it’s sent ASCII-encoded, for example:<\/p>\n This means that there’s one ASCII character for every digit. So to get the content length, I just count the digits like so:<\/p>\n That’s the whole program. Here’s a link to the whole thing in its entirety<\/a>.<\/p>\n Here’s what the Pachube live feed<\/a> looks like:<\/p>\n\n
The Circuit<\/h3>\n
![\"\"](\"https:\/\/tigoe.com\/pcomp\/code\/wp-content\/uploads\/2010\/03\/analogIn_bb-297x300.png\" "\\"analogIn_bb\\"")
<\/a>![\"\"](\"https:\/\/tigoe.com\/pcomp\/code\/wp-content\/uploads\/2010\/03\/analogIn_schem-247x300.png\" "\\"analogIn_schem\\"")
<\/a><\/p>\n
\n![\"\"](\"https:\/\/tigoe.com\/pcomp\/code\/wp-content\/uploads\/2010\/03\/IMG_8567-150x150.jpg\" "\\"IMG_8567\\"")
<\/a>![\"\"](\"https:\/\/tigoe.com\/pcomp\/code\/wp-content\/uploads\/2010\/03\/IMG_8564-150x150.jpg\" "\\"IMG_8564\\"")
<\/a><\/p>\n![\"\"](\"https:\/\/tigoe.com\/pcomp\/code\/wp-content\/uploads\/2010\/03\/IMG_85481-150x150.jpg\" "\\"IMG_8548\\"")
<\/a>![\"\"](\"https:\/\/tigoe.com\/pcomp\/code\/wp-content\/uploads\/2010\/03\/IMG_8548-150x150.jpg\" "\\"IMG_8548\\"")
<\/a><\/p>\nThe Data<\/h3>\n
PUT \/api\/76.csv HTTP\/1.1\r\nHost:\u00a0www.pachube.com<\/a>\r\nX-PachubeApiKey: ENTER_YOUR_PACHUBE_API_KEY_HERE\r\nContent-Length: 19\r\nConnection: close\r\n\r\n12,14,66,23.03,text<\/pre>\n
PUT \/api\/76.csv HTTP\/1.1\r\nHost:\u00a0www.pachube.com<\/a>\r\nX-PachubeApiKey: ENTER_YOUR_PACHUBE_API_KEY_HERE\r\nContent-Length: 3\r\nConnection: close\r\n\r\n126<\/pre>\n
The Code<\/h3>\n
\r\n[include file=\"..\/..\/code\/Arduino\/pachube_client\/pachube_client.pde\" start=\"78\" end=\"109\" clean=\"true\"]\r\n<\/pre>\n
[include file=\"..\/..\/code\/Arduino\/pachube_client\/pachube_client.pde\" start=\"20\" end=\"38\" clean=\"true\"]<\/pre>\n
[include file=\"..\/..\/code\/Arduino\/pachube_client\/pachube_client.pde\" start=\"40\" end=\"46\" clean=\"true\"]<\/pre>\n
[include file=\"..\/..\/code\/Arduino\/pachube_client\/pachube_client.pde\" start=\"48\" end=\"58\" clean=\"true\"]<\/pre>\n
[include file=\"..\/..\/code\/Arduino\/pachube_client\/pachube_client.pde\" start=\"62\" end=\"66\" clean=\"true\"]<\/pre>\n
[include file=\"..\/..\/code\/Arduino\/pachube_client\/pachube_client.pde\" start=\"70\" end=\"76\" clean=\"true\"]<\/pre>\n
1003<\/pre>\n
[include file=\"..\/..\/code\/Arduino\/pachube_client\/pachube_client.pde\" start=\"117\" end=\"130\" clean=\"true\"]<\/pre>\n
\n
![<\/a>](\"https:\/\/tigoe.com\/pcomp\/code\/wp-content\/uploads\/2010\/03\/IMG_8564.jpg\"){kind=link}