DHT22 + Arduino

I recently purchased a DHT22 (Also known as RHT03 on Sparkfun) from Proto-Pic temp and humidity sensor with the aim of using it as an outdoor sensor in the garden. Although there are several DHT22 libraries on github I couldn't get the nethoncho one (or the patched forks) to return anything other than checksum error.

However the combined dht11/22 one I found linked on arduino.cc seems to work just fine. Need to test with -ve temps next but an overnight plot on the bench seems reasonable

Despite many forums saying that it needs 5v I've managed to get it working OK with the 3.3v pin on my nanode, next step is to test on a jeenode and send the output via RF. Oh, and then get a solar panel to run the thing...

Teleinfo update

I''ve been using a teleinfo shield on a nanode to try and datalog our electricity usage, but the logging to the CSV file kept truncating as if the arduino had locked up. There have been discussions elsewhere that this may be related to the code in arduino 1.0 so I decided to rewrite a step at a time to try and debug the problem.

Some observations on the way:

1) having to flip a jumper over on the shield between programming and run is *very* annoying in a cold garage, so I'm going to rewire it slightly to use SoftwareSerial on a spare input (leave JP1 open and wire from one side of it to a spare pin) - I already have a link since the shield tries to use DIG6 by default which is used by the red LED on a nanode.

2) the arduino IDE doesn't like anything other than 8N! on the serial monitor. close it and use kermit. if you can't read serial with kermit, then it's *very* broken :-)

3q) our usage is going UP not down :-( -- lowest figure I managed to get the baseline to was 340VA

With a very simple logger

    Serial.print(char(meter.read()));

I can stream the output to a kermit session log as

^B
ADCO 040222048573 <
OPTARIF BASE 0
ISOUSC 30 9
BASE 040912359 ,
PTEC TH.. $
IINST 002 Y
IMAX 029 J
PAPP 00340 (
MOTDETAT 000000 B^C

next trick is to try and get the processing organised into blocks and validate the checksum, but my code doesn't seem to detect the stx/etx properly

void loop() {
if(meter.available()>0) {
  if((c = meter.read()) == 02) {     // start of block
    Serial.println("DEBUG: Start Loop");
    while((c = meter.read()) != 03) {      // Loop until end of block
      Serial.print(char(c));
    }
    digitalWrite(LED, LOW); // Flash LED
    delay(50);
    digitalWrite(LED, HIGH);
  }
}
}

so mode debugging called for. Once thats done, then I'll send the values to an emon style display over rfm12b

They're following me!

As you know, I've been 'tweeting' the Status of the LHC from the 'Page1 comments' field. Decided to knock up a quick script to plot the number of followers over time, and lo: