Paul

Hi there,
i have a question for a project that bugs me for some time now, because i dont know which sensor to use.

If i want to measure the angle a camera is flipped to the front (lets call it x-axis so the lens is looking to the ground) and to the side (lets call it y-axis so the camera would make a portrait instead of a landscape photo) which kind of sensor would i have to use?

Do i have to use a accelerometer oder do i have to use a gyro?

Just a note on using a gyro. All of the solid state gyros, MEMS gyros, that are readily available be they one, two, or three axis measure the angular rate, i.e. velocity, of rotation about each axis. You will see the the gyro's range listed as degrees/sec, e.g. 100 degrees/sec. This is the maximum angular rate the gyro can report. It is output as an analog voltage, there are some digital output MEMS gyros available. The analog voltage ouput is generally a range from 0 to a few hundred millivolts. For most gyros the "at rest," i.e. no movement, voltage is a positive voltage in the middle of the output voltage range. A clockwise rotation of the gyro on a given axis will generate a positive voltage, which will be reflected as a voltage higher than the at rest voltage and a counter clockwise rotation of the gyro will generate a negative voltage which will be reflected as a voltage lower than the at rest voltage. Through A/D conversion and application of the proper scaling factors the output voltage of the gyro is converted to the angular rate of the gyro.

The important thing to note here is that the gyro is not reporting the angle it has rotated through. It is reporting the angular rate of the rotation it has undergone. To obtain the actual angle the gyro has passed through requires integration of the the angular rate over the elapsed time of the rotation - a nontrivial exercise.

This weekend I will be adding a two axis MEMS gyro to a Netduino based project and will be posting the results of calibrating it, measuring angluar velocity and hopefully an algorithm for integrating over time to get the angle of rotation.

Paul

Hari - I tried your recommendation last night and everything worked fine. Again, thanks for your initial post of the SerialInputClass and follow up. Corey - Your evaluation and recommendations regarding the SerialInputClass are most welcome. The class was originally created by another forum member and provided a great starting point for me to work with serial I/O on the Netduino. While I've been in IT more years than I'm willing to admit, let's just say the state of the art PC when I started in the business was based on the Intel 8008, it has been a very long time since programming was my primary job responsibility. As such my C# is not the best and one can learn only so much by reading books and Googling for ideas. Trying stuff out and getting feedback such as yours is what I like most about this forum and I will try out your suggestions this evening. Again, thanks for the feedback and I look forward to more of your posts. Paul

Hari, Thanks for the feedback. Your SerialPortLearn post has taught me a lot and has proven very useful. In fact, the first project I did with it was to construct a calcualtor which used the computer keyboard as input and displayed the calculation being input as well as the results on an LCD display. I look forward to implementing you recommendation tonight. Paul

Ignore this post. I had my question answered by rereading the "fast few facts" at the top of this thread. Paul

I'm looking for a good LiPo battery charger. Something semi universal as I need it to at least be able to charge 2 and 3 cell batteries from 300mAh up to 3Ah or 4Ah. At the moment, all of my batteries are 7.4v. I've looked around quite a bit and keep finding chargers that seem very sketchy after reading their descriptions and reviews. The one that sparkfun suggests has been out of stock for a while.

Can anyone suggest one that they've used and are happy with?

Thanks.

Check out "Hobby King," http://www.hobbyking...re/uh_index.asp
Very highly rated for price and customer service. I did a quick check and under the battery listings there are seven pages of charger products.

Paul