11/3/14 Update

11/3/14

This week I learned all about I2C protocol. I2C protocol, or inter-integrated circuit, uses a master/slave combination to talk to multiple sensors from one master. The master being a microcontroller for example. At first I tried to find a way to use sensors without I2C, however, as I looked I found that more and more sensors actually used I2C and that there were a lot of resources online for help. For example the air speed sensor I am using now uses I2C. And the altimeter from Eagle Tree (that is missing) also does.

I have not yet gotten the air speed sensor to work using I2C but I think that this is the right path since I keep finding more and more information on I2C. One problem I just ran into is that my “wire library” is outdated. I’m not exactly sure what that means or why it is outdated. But the wire library has to do with my code being complied and once I update my wire library (working on it) I should be able to start actually testing my code.

This week I would like to purchase some components (details and links at end). Including an altimeter, camera, and transmitter/receiver. The altimeter is small, using I2C, has a detailed datasheet, and example code with ardiunos.

The camera, Airy 3g Mini Camera, is only 3 grams. It is used by a lot of drone hobbyists and also recommends a transmitter/receiver combination (Boscam 5.8Ghz FPV System (TS352 TX + RX305 RX / 500mw)). The transmitter does need 11.1 V and is 55 g (0.12 lbs).

In terms of GPS components I am still looking. I’ve found that it is hard to pick one because they all have so many different specs. Finding one isn’t the problem, it is picking it. So far I am favoring the GP-635T because of its fast (1-5Hz) update times and its large amount of channels (fasting locate time). It is also really small and can be powered by a 3.3-5 V source with a 56 mA current draw.

I have also looked at on board data storage for the microcontroller. I believe that it has 128k of SRAM data memory which can be used for storing the sensor data on the board. I am concerned about the GPS data requirements. From what I have read it seems that the GPS could quickly use up the storage space within the SRAM so that is something to continue researching.

All in all I think I2C is the way to go for programming the board and the related sensors. I’m not sure how the GPS connects to the board. The GP-635T says something about TTL connection.

My goals for this week are to fix this weird wire library issue and then get the air speed sensor running. Once it is running I’ll know I can use the I2C protocol and can order the altimeter.

Altimeter $9.95
Camera $69.90
Transmitter/Receiver $139.90
Total $219.75
Total +15% (Shipping/Tax Estimate) $252

 

GPS $39.95

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