Back in Q1 of 2013 I posted a sample application which called an Azure Service Bus end point just to confirm that the certificate configuration etc. was good.
Since I published that sample the Azure Root certificate has been migrated so I have created a new project which uses the Baltimore Cyber Trust Root certificate.
The sample Azure ServiceBus client uses a wired LAN connection (original one used wifi module) and to run it locally you will have to update the Date information around line 24.
One of my co-workers is involved with a group that run “code clubs” at local schools teaching high school students how to code.
We got talking about projects which would appeal to the students and I suggested making a mobile phone. This is my prototype
It’s more Nokia 5110 than Nokia Lumia 820
If you want to build your own (the parts list will grow as I add GPS, accelerometer, compass, screen etc..)
For V0.1 of code one button sends and SMS to my mobile, the other button initiates a voice call to my mobile. The initial version of the code was based on the SeeedStudio GSM Shield Netduino driver on codeplex.
The later versions are based on the CodeFreakout Seeedstudio GPRS Shield drivers which are available via NuGet. I have added some functionality for dialling and hanging up voice calls which I will post for others to use once I have tested it some more.
So according to cuno and co NetMF is a viable processing platform for a quadcopter. I was worried about the GC and it looks like as long as I’m really careful about allocating memory (strings, buffers etc.) I should be okay. It will be like writing code for embedded micro controllers (V25 & HC11) in C not long after I left university,
Have also been reading up about proportional-integral-derivative controllers (PID controller) here and building a basic C# implementation.
Next step some PWM code for interfacing to my Turnigy Multistar 10 Amp ESCs. I wonder if my larger scale quadcopter will cause any issues?
The quadcopter will need to determine it’s orientation then update the thrust to be delivered by each motor many times a second. So I was interested to see how fast my Nedtduino plus 2 could read data from the MPU 6050 accelerometer & gyroscope. I stumbled across this blog and it appears that they are building a Quadcopter as well(Google translation was hard work to read).
There was also some very useful C# NetMF code which I used as the basis for my performance test harness.
10,000 readings of 16bit values from the Accelerometer (X,Y,Z) Gyroscope (X,Y,Z) and temperature sensor. The initial run didn’t look to positive
21.78, 21.77, 21.77, 21.77, 21.77, 21.77, 21.77,21.77,21.77,21.77 sec Avg 21.77
Which is roughly 460/sec
I then had a look at the I2C interface code and noticed that the bus speed was set to 100KHz so I increased it to 400KHz
10.33, 10.23, 10.23,10.23,10.23,10.23,10.23,10.23,10.72,10.23 Avg 10.29
Which is roughly 970/sec
I then had a look at the I2C interface code and changed the way that the register values were read so the array of registers to read didn’t have to be loaded.
8.55,8.57,8.55,8.57,8.55,8.57,8.57,8.57,8.55,8.57 Avg 8.56
I think 1170/sec should be sufficient, but I’m going to have a look at the Digital Motion Processor (DMP) capabilities of the MPU6050. This will require significant effort as there currently (June 2013) doesn’t appear to be any NetMF support for this approach.
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