LEDzep – TWI, LEDs, nRF, refactoring and presentation

Well it’s been a while, but I haven’t been inactive !

This Week-End I mostly (and only) worked on the final presentation as I was busy at a hackathon Saturday (which served as a great day off with lau and former ROSE students).

Since then I read some other application notes on the nrf51822 (and managed to remember the full name of the chip doing so ^^). Thanks to that I’ll (hopefully) be orders of magnitude more efficient writing code for it.

Later we planned to work with Thomas on using the Digital Motion Processor of the mpu9150 (which we overlooked at first), which could do all the angles calculations and tap detection, and thus saving us a lot of time. To do so Alexis and Sam lent us two TWIs (a great board made by drix !) which already has a nRF51822, a mpu9150 and a serial port : all we needed to get to know the DMP. Unfortunately we haven’t managed yet to find a way to lower the voltage of our JLINK probes, as the nrf has to be flashed with a 1.8 voltage and our probes are configured to give 3.3V. We tried quite a long time (about a day) different tricks to find how to do so, eventually we will have to write a jlink script to reflash our probes (we hoped to find an option to do so in command line, but no success so far).

Today, I remembered that we had a PSSC to fill : having a balloon structure with LEDs, so I ‘improved’ Thomas great structure by putting LEDs on it. So I had to spend a while soldering, but the result is rather nice, as you can see 🙂

Capture d'écran de 2014-04-10 02:42:11 IMG_20140410_003917 IMG_20140410_003929  IMG_20140410_004220 IMG_20140410_004439


EDIT : as Alexis asked, here is a little video


Félix Raimundo


7 comments to LEDzep – TWI, LEDs, nRF, refactoring and presentation

  • Seriously, you have my email so ask me if you have any problem with TWI, we can skype/hangout too.

  • Félix Raimundo

    Don’t worry, the problem comes from our probes, not from the TWI 😉
    (It’s just that I’m a bit late to post in the Logbook, but we realized this issue 2 hours after contacting you). What’s more where would be the fun without some troubles 😉

  • Félix Raimundo

    Plus, having to program the voltage of the probe will be an issue for every one, as no one thought of checking this issue while designing the PCB. We might as well be the first one to work on it 😉

  • You won’t have the issue as you’re using the internal LDO if I remeber well.

    But as I told you by email, connect the voltage input (3Vi) to the voltage output reference (1.8Vo), and use a 3V power supply.
    It works with nordic/segger programmer, that’s what my friends are using (I still assume that’s the one you’re using as my email questions didn’t get any answer).

    Good luck ;p

  • Félix Raimundo

    Actually, the problem we had is that there were some varnish on the battery connector so at first it couldn’t work. Then we try a lot of thing to flash it, and doing so we managed to burn the TWI, which explained why it didn’t work after ^^.
    I’m restarting now with an unburnt one, hopefully it should work at first try (now that we have removed the varnish).

  • Any video of the LED lightning or are you keeping the surprise for the final defense ? 🙂

  • Félix Raimundo

    Yup, I just forgot to post it, I’ll edit the post right now 😉