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!

 

Caro

2 comments to Clock and stuff

  • Alexis Polti

    PnR is no black magic : it just needs a little practice. Like cooking or riding a bike 🙂
    Concerning your Hackster site, you should make it public now, don’t you think so ?

  • carreau

    It’s done 🙂