LEDzep – PCB sent in prod

With the great help of Alexis, the PCB was inflatable games finished this afternoon. From now on I’ll be doing software. I’ll have a look at what we can do with the ADMP Micro that we put on the PCB, and then assist Nicolas with the BLE.

I just want to present a quick summary of hüpfburg kinder what’s on the LEDZep PCB, to close that chapter definitely. So I made that visual presentation about the content inflatable slide and the connections of the LEDZep PCB.

PCB summary

LEDzep – Progress on Android


I have made some progress on BLE and Android. At first, I tried to exchange simple values like  the battery level between the LEDzep’s Android app and the nRF81822. It helped me to understand how the Android API works with BLE.

Then, I decided that we should establish all the services we are going to need to exchange data between the balloons and the operator.
After some thinking, I came up with this first draft:

  • Battery Service : to exchange the battery level
  • Generic Access : to exchange balloon’s name and some other useful information
  • Link Loss : to be alerted if we lose radio link with a balloon
  • Immediate Alert : to be alerted if a balloon collides with something
  • Tx Power Level : to exchange data about the Tx power level

Those services are the standard services defined by the Bluetooth SIG (see We also have to add some services because they are not standard:

  • Command service: to exchange command data for motors and servomotor
  • Altitude service: to exchange data provided by the altimeter
  • Compass service: to exchange data provided by the compass

As I said, this is an early draft and it is very likely that we have to change it a bit.
Thanks to Alexis’s mail, I was able to set up a BLE sniffer. It’s going to be really useful for the upcoming work on Android and nRF51822.

More to come soon!

LEDzep – Board and BLE

Today I took a little rest and only worked the afternoon.

As Thomas routed the new PCB version (a ‘little’ updated by Alexis) I checked the pinout while I created the project board.h. It was longer and more boring than I expected, but we should be able to use this one as soon as we receive out boards. I also tried to configure the peripherals of our future board, but after an hour of doing so I realized that it was rather useless as I wouldn’t be able to use it and would probably have to rewrite it completely…

So I started to work with Benjamin on the BLE, he welcomed my arrival rather warmly as he was working alone on it for a week. After creating a clean repository, he introduced me to sole of the BLE subtleties and we managed to tackle a bug that troubled him this afternoon.

We also established a roadmap of features we will need for our different projects which will help us to work smarter and together 😀

Next step : Trying to implement data streaming from the BLE chip (if it’s possible in connected mode), implement communication between the nrf51 and the stm an then call functions remotely on the stm.


LEDzep – finishing PCB, working on actuators


These days we worked a lot on our PCB. We have fixed a lot of connections that were missing in the latest version. We also determine the other components we needed to complete the architecture. We added two voltage regulators in order to provide the Vcc and the actuator power. We went to the communication and antenna department of Telecom in order to determine our needs, but they afferm that, seeing our short timing, it would have been inappropriate to create our own antenna, we would have spent to many time with waves simulators and it would have been to risky. So we prefered to take an antenna already done, it is saffer. We finished a first Routed version. We will send it to the production line as soon as possible.

In parallel, knowing all the connections, I made the routing table in order to start working on actuators commands with the right PINs.
Today, I made functions that command the two motors through H-bridges with PWM input interface. We can now set their speed, their rotation mode and put them in low power energy. I Worked also on servo comand, we can now enslave it with with a degree accuracy. I just notified that they can consume a lot: 200mA maximum. But it appears only when we apply an important negative moment. No problem therefore for our ballon.

Next days we will implement the other devices and work on the BLE structure.

Good evening,


LEDzep – Long live the PCB

These last days I worked on the LEDs (after I was done with the bit banging i had to use SPI with DMA).

We also worked a lot with Thomas and Daniel on the PCB, the schematics were finished yesterday and we drew the PCB this night (for me) and this morning (for the others). Unfortunately my nightly version wasn’t selected (thus the title of the post), fortunately we worked all together this afternoon and were able to pick the best of both versions in order to have the BEST PCB EVER ! (should Alexis say it’s ok).

From now on we will be able to focus more on the software part of the project (at least until we receive the soldered PCBs), which makes me rather happy as I am eager to code 🙂

LEDzep – PCB

So today, as well as last week inflatable water slides end, it was all about the PCB.

We now have a first version of the electrical schematic to propose. It still has several flaws, and we have to add the voltage regulator, aufblasbares zelt indication leds, several missing inflatable tent capacitors, and to change the nRF clock which is not the right one.

Cf the post of my collegue Daniel for the pic.


LEDzep – PCB


After a tiring Athens week in Madrid, I worked today with designView in order to create a first version of our PCB. We choosed all our components so we can now work on connections. We tried to understand all the PIN specifications and how we will use all the devices.
Here is an overview of our work:
Some points are still not finished on this PCB:
– We must meet an expert in order to determine precisely how to make our antenna. In fact, we need a large scope for our balloons, so it will be better to make our own antenna on the PCB rather than taking an already made.
– We will, certainly tomorow, add voltage regulators in order to provide a safe voltage to the STM32.

Than, next step: Expedition PCB!


LEDzep – BLE and Android


This week, I mostly worked with my team on selecting the right components, eg. the microphone, the battery, the altimeter, the BLE chip… Thomas did a great schematic to sum it up. We are now focusing on the PCB design to be able to send the PCB to production as soon as possible.

This weekend, I worked on my nRF51822 evaluation kit. I was able to flash a proximity app example. I can connect to it using my Android smartphone (Samsung Galaxy SIII / Android 4.3) and the app nRF Toolbox from the Google Play Store. I can light up a LED on the board from the phone or ring the phone from the board, all using Bluetooth Low Energy. It works really great!

I also started to work on the Android app. More to come very soon!


LEDzep – Global structure (FIXED)

So today I finished my Athens class on biomecanic inflatable obstacle course at Art & Métier Paristech. I also sent the confidentiality papers for Parrot, at last.

We are settled on almost every components aufblasbarer wasserpark in the system, and are just inflatable water park hesitating on the battery current, the battery reducer and protection system and a few other things.

Here is a global schematics of the system :

Screenshot from 2014-03-22 18:28:22

And this weekend, PCB design !

LEDzep – Working on the BOM

Yesterday i worked a little on the LED stripe, the results were rather great and we were convinced by the LED model (WS2812b) so we will use this one on the balloons. I’ll let you judge :

Today I tried to advance on the choice of the components to use for our PCB, I managed to choose the one we are going to use : the DRV8837

Tomorrow we will choose the IMU, power regulators, battery and mic so that we can start to work on the PCB as soon as possible (tomorrow night or Saturday).