Implementation around the IMU

now that the TP is over we will focus only on the project. Yesterday I have been writing the code for the IMU, defining the mask for the registers’s names and the configuration parameters. I have also wrote the functions to communicate on an I2C bus with this IMU, chibiOS saved me a lot of time with that.
I can’t still test the whole thing as we don’t have our PCB but I think it will be possible on Friday at least.
I am also studying how to implement the algorithm, we will use a circular buffer for our calculation so we don’t have to keep all the results in RAM and a mailbox (from chibiOS’s structures, il works like an asynchronous FIFO) between the IMU’s data and the DTW implementation, that way it will be possible to run the calculation on live, without waiting for the end of the measure.
That’s all for now.

long time no seen

I haven’t posted for a while so here is what I dis this past week : along with the team I did the PCB, or rather the routing and it was quite hard work. In the process we changed our micro-controller for a smaller one (we had chosen a stm32f427 and eventually sided for a f405) as our constraints on the size of the prototype are really important. We also run some test on IR receptors and made some progress on using ChibiOS.
All of this while following some classes during the Athens week. By the way, I had to implement an algorithm that might be useful for our implementation of the DTW algorithm : we are bound to use a circular buffer to save memory and that’s part of what i did, so not very complex but at least done.

Choosing the components and Starting the Schematics

Hi everyone,

This is a team post for Expelliarose as we thought that for now, since we are all doing more or less the same task, a single post would be better than repeating five time the same stuff.

So today we chose most of our components,  the processor will be a STM32F427VG because we still don’t know how much power we will need to run the recognition algorithm quickly and therefore this one seems quite convenient with its 180 MHz. We still need to determine cleanly the global consumption to choose the regulators.

Quite important also, we made a more precise design for our wand as it matters a lot since we will have several components quite close from one another at the far end of the wand (a RGB LED, an IR emitter and an IR receiver).

We also started the schematics on ExpeditionPCB, giving a look to every datasheet, and mainly the processor’s one, to see which pin to connect the devices on.

Choosing the components

Today we choose the components we will use for the project. We also took a look at how the DTW algorithm works as if it’s implemented trying to keep all the data, it takes a lot of place ,in our case as we will make comparison on 6 dimensions, we would need 1 Mb, fortunately we can reduce this number to a few Kb. We decided to use a Cortex-M4 processor with a FPU, we also made a choice for a lithium battery and thought about the design this would imply (along with other components for the sensors and the leds) .Last but not least, we made the list of the PSSCs and discussed a bit about how to have a well-organized team work.



we have made some evolution on the project. After considering HMM algorithm and the DTW algorithm, we chosed this last one as it is simple, both in number of instructions and in mathematical complexity and it still gives good results according to some docs we found on the net. We still have to decide were all the calculation will be made as sending all the data given by the IMU through BLE might not be convenient, this will help us determine exactly which components we will use.

In the same time, I have made some progress on installing Arch Linux but it still won’t work because it can’t find (though I can see it) the file vmlinuz-linux when booting.

[Expelliarose] Let’s go

So this it, we are starting our project. For now we must find how we will plan our work and therefore find the PSSC. Also, as there is not much time before the PCB’s deadline, we begun looking at how to make it and which components to use. Meanwhile, I am trying to install arch-linux in dual boot with windows 8 and it doesn’t work at all.


Coming at last


ok I know I am a bit late for a first post but here I am so let’s get started !

So, I am working on the LED tutorial as it is impossible to think about a embedded device that would not include some of those, I currently am searching for info about led drivers.

I spent also some time reading the slides about bus and communication, and tutorials for installin Arch Linux.