Data lgger shield kit

[carbazole]

Hi- I'm not exactly new to electronic kit building but I am new to arduino and recently bought the data logger shield kit to go with an uno I have. My son and I are going on a week-long BSA camping expedition and though that a mini-weather station would be neat to bring with us (and play with the data later). So, with that in mind, a few questions:

1) The kit comes with temperature and light sensors. I have purchased with it your AM2302 (wired DHT22) temperature-humidity sensor and your BMP085 Barometric Pressure/Temperature/Altitude Sensor- 5V ready. How hard would it be to either add these sensors to the kit, or replace the temperature sensor with the temp/humidity sensor and replace the light sensor with the barometric pressure sensor? Please also note that I'm not all that familiar with coding, so a description of how the code for that would be altered would be helpful as well.

2) Considering the baterry life, the size of the data card, and the relative sampling rates of the sensors, what do you recomend for data point aquisition intervals? 1/min, 1/10 min, 1/hour?

3) Finally, I will definitely use fresh batteries, but was considering bringing my solar USB device charger:

http://www.amazon.com/gp/product/B004GV ... 06_s00_i02

Can I hook it up to the USB input of the arduino during the day and save the battery box for night with out much data loss/errors created by the switch over? Better yet, can I build a simple device that will switch automatically?

Thanks in advance for your help,

Steve

[adafruit_support_rick]

1) The kit comes with temperature and light sensors. I have purchased with it your AM2302 (wired DHT22) temperature-humidity sensor and your BMP085 Barometric Pressure/Temperature/Altitude Sensor- 5V ready. How hard would it be to either add these sensors to the kit, or replace the temperature sensor with the temp/humidity sensor and replace the light sensor with the barometric pressure sensor? Please also note that I'm not all that familiar with coding, so a description of how the code for that would be altered would be helpful as well.

The BMP085 is an I2C device - you would connect it to Analog Pins 4 and 5, which double as I2C clock and data lines. The AM2302 is a digital-data device, and requires a free data pin for communication.

Both of these should happily coexist with the temp and light sensors in the kit. See the tutorials and libraries for sample sketches. Essentially, you would have to download the library for each new device, include them in your sketch, and declare an object variable for each. Poll the new devices in the same places you currently poll the temp and light, and extend your log record to include the new information. It should be quite straightforward to take the relevant initialization and polling code out of the example sketches and integrate it into your logger sketch.

2) Considering the baterry life, the size of the data card, and the relative sampling rates of the sensors, what do you recomend for data point aquisition intervals? 1/min, 1/10 min, 1/hour?

Sampling the sensors and writing the card will not appreciably alter the power consumption. The main factor is the time that the arduino is powered up. There is a discussion over on the Arduino site about power-saving techniques.

3) Finally, I will definitely use fresh batteries, but was considering bringing my solar USB device charger:

http://www.amazon.com/gp/product/B004GV ... 06_s00_i02

Can I hook it up to the USB input of the arduino during the day and save the battery box for night with out much data loss/errors created by the switch over? Better yet, can I build a simple device that will switch automatically?

I don't know if the charger provides enough current to operate the Arduino directly. I see that the charger also has a built-in battery - it's possible that it could provide 24-hour power for your kit. Your best bet is to try it and see.

In terms of switching power, if your sketch always makes sure that the data file on the SD card is closed and saved after each update, you should be able to switch power supplies without any data loss. If you prefer to buffer your file data and only update the file periodically, you might arrange to have the arduino's LED light up whenever it is not safe to power down, or something like that.

There is another arduino discussion on power supplies here. If you scroll down to the bottom of the page, there is a section called "Et Cetera: The things that don't "fit" elsewhere!" that talks about switching between power supplies.

Good luck!

[carbazole]

Thanks, will give it a try and post back if there are any problems