Switching processor and the missing LEDs

Forget what I’ve said in my last post.

Finally, we’re not overclocking.

We’re not even using a stm32f427.

We’re switching processor for a stm32f405, which runs at 168MHz but which is smaller.

So, with Lélio we sprent the afternoon updating our routing tables, schematics, etc.


And tonight, we’re working in the A406. Hugues, Lélio and I are :

-re-doing the rooting from scratch, (our first aptempt was a mess)

– tring to test our IR receipter without the IR emitter (we’ve lost them !). We found some remote controller that uses IR but we are not sure of their frequency (it could be 36kHz, 38KHz, 50kHz, …) and Lélio is having a hard time…


But tomorow will be a brigther day! (I hope)

See you !


Clock and stuff

So… I haven’t post here recently. But I worked on a lot of things !

First of all, I took a look at the different PLL and clock in our stm32f427. But, there is something strange : if you want to use the USB(you’ll need a clock at 48MHz), you definitly can’t use your cpu at its maximum speed (180MHz)! So, two choice: either we only run at 168MHz – but as we choosed this CPU just because it was a little faster (for our recognition algorithms), this idea make me sad – or we can overclock the CPU at 192 MHz – and Alexis allowed us to do so !

Ok… I’m happy mostly because, after this few weeks of reading dozens of datasheet, I can finally say “F**K THIS DATASHEET! I will do my way and not with your strange specification that I take hours to understand!”

But it will be fun – even if we discover at the end that this overclock was useless.


I looked at the other PLL and clocks that we need. For example, in order to modulate our IR emission at 38kHz (usefull to avoid problems with other electric lights), we needed a timer ;  also we had to create a clock for our I2S connection (for the micro).


I also changed and verify the pins connection, in order to prepare a little the routing step: I wanted to have the connection with IR emmitter/receiver to be on the top of the procesor but the connection with the pins of the bottom. But, luckily, our pins choice was already more or less good!


With Hugues, the other day, we changed some resistor because they didn’t dissip enough power.


And this week-end, Iworked (a little) on the PCB with Hugues and Lélio. But as Lélio said, it’s pretty hard. Very hard. Black magic.


And last news: we finnaly post something on our Hackster !

I’ll try to post quicker next time!



Chapter 7: The Sorting Hat

Sorting Hat: Not Slytherin, eh? Are you sure? You could be great, you know. It’s all here in your head. And Slytherin will help you on the way to greatness, there’s no doubt about that. No?
Harry: Please, please. Anything but Slytherin, anything but Slytherin.
Sorting Hat: Well if you’re sure, better be… GRYFFINDOR!
Harry Potter and the Sorcerer’s Stone (2001)

Hugues forgot to say that we worked on the design of the wand today – and that Aïmen wants us to be in Slytherin (he wants us to put a snake on our wand !):


At the end of the wand, we will use:
1 IR transimitter at the very end of the wand
3 IR receptor on the green ring + 1 behind the transmitter
A very cool decoration with a snake and a RGB LED in its mouth

We have other schematics of the entire wand and the future emplacement of the componant, but as I forgot my notebook in the school, I can’t show it to you for the moment…


See you soon !


Motion recognition

So we’re looking at motion recognition algorithms for our magic wand.

Basicaly, we found two mains algorithms : the HMM (Hidden Markov Method) and the DTW (Dynamic Time Warp) . We only need to analyse the mouvement once it is done, and the DTW algorithm seems to be a good solution but we are still wondering about the size of the data we will get from the IMU and how much of it should be processed on the wand’s microcontroller or the smartphone.

Chapter One: The computer who boots

Voldemort: Don’t you turn your back on me, Harry Potter! I want you to look at me when I kill you! I want to see the light leave your eyes! 
Harry: Have it your way!
Voldemort, Harry: Avada Kedavarose!/Expelliarose!
Harry Potter and The Gobelet of Fire (2005)

Everyone knows how powerfull an Expelliarose spell can be… I hope my team will be powerfull and relentless too!
I hope we’re going to create a good game… and that we’ll be able to play it in two months!

Today, I finished the installation of Arch on my laptop (I used to have problems with internet connection) and I installed Arch on one our PC at school… and as 16nek, I had problems with UEFI! I still have some little problems with the Xserver but… I’ll manage to fix it.

Today was also the first Sam’s lesson about real time OS and with my fresh-usable laptop, I can finally began the work on the STM32… or maybe just installing the tools that I need.

Our group took a little time to talk about our problems (specially the detection and recognition of an opponent – see lelio’s post), to divides the task and to look up at some specific composant.

And since I haven’t post in a long date, here are some old news:

  • I’ve finished and send my tutorial about LEDs… I enjoyed the part about colorimetry because I have a few notions in photography and so a different point of view on the thing
  • I worked a little my signal integrity lesson but it’s still very very very hard
  • I installed Arch on my laptop (though I finished my networkconfiguration today…)
  • I realised that it was hard to write in english (so, excuse me for bad english!)


See you !

Here we are !

Today – the 2nd day of ROSE – seemed a little harder than the first one. Maybe because we had more than 4 intensive hour of lecture about bus and very detailed protocol (Too much information for my little brain! I scramble up the names… I think I’ll have to re-re-read it in a day or two).

Gladly, tonight I’ve made something funnier: a brainstorming on my two favorite subjects – Sorcery and Battle Royal.
– I tend to agree with lerela on Sorcery and I hope I will play to this game, even if I don’t create it.
– For Battle Royal, the problem was that the game had no real purpose :
the original idea was some people are wearing a very dangerous necklace and a master gives them orders and controls them through this necklace. If they don’t follow the order, something happens to the slaves (explosions or even worse ! ). The game world is interesting, but… something is missing.
I had an idea of game play that gives everybody a purpose : everybody is wearing a necklace and you are the master if you’ve got a very specific object in your possession. So the slaves are trying to steal this object in order to become the master ; and the master is hiding because he doesn’t want to become a slave again.
Maybe we’ve got something.

Also, for my tutorial – which is about LED display – I tried to remember what I learned about LEDs in the project I’ve made last year with Alexis&&Sam. I also began to collect informations about charlieplexage, etc.