Le Blog

...yes it's in English !


BLE transfers using MIT App Inventor for Android

MIT’s App Inventor I have recently discovered MIT App Inventor 2 for building Android apps and I must say I’m quite impressed. Before that, I had learnt some basics of Java and taken on learning Android and the Android Studio IDE — with some success,... read more

Monitoring the LiPo battery

In this post we’ll be looking at the behaviour of the battery as it discharges, and how measuring the voltage provided by the LiPo can be used as a gauge — i.e. an estimate of its fullness level. When dealing with LiPo battery, it’s important to have... read more

LimiFrog + GPS

Some time ago I did some tests connecting a GPS module to LimiFrog. I thought I would write a few words about what I did. Here they are…   The GPS module I acquired the “Ultimate GPS Breakout” board from Adafruit (full description here).... read more

Catching Up !

Christmas already ! Been so busy since the launch of the kickstarter campaign that this blog didn’t get much update. Anyway, a quick run-down on what happened since : LimiFrog got a Twitter (@LimiFrog) and a Facebook account — check out the... read more

Android Smartphone Connection Demo

This clip shows an Android smartphone running a simple App developed to communicate with LimiFrog over BlueTooth Smart. The App connects to LimiFrog and gets sensor data from it. Based on the magnetic field information it receives, it estimates the orientation of the... read more

Teaser #2

A second teaser based on footage shot for the upcoming kickstarter video. Focus on technical features this time. Image and sound not fully calibrated yet, but that gives you a taste of the... read more

Hand-tracking robot demo

Here’s another clip that demonstrates some LimiFrog features using that small robot I built. The robot moves forward or backwards depending on the distance to the object that’s in front of it (my hand in this case). Distance detection is performed using... read more


I’ve just uploaded a teaser built from images shot for the LimiFrog kickstarter video — mostly a sequence where LimiFrog is used to remote control a small robot.     A few words about the robot demo in this sequence – The objective is to... read more

If you read some French…

Still time to catch the summer  issue of magazine “Programmez!”… lighter than usual for the holidays, with maker-oriented articles about boards, 3D-printing, RPi-based systems — and a full article on LimiFrog (formerly La BlueFrog, the name... read more

An overview of the STM32-L4

At the early days of the project, the choice of the micro-controller for LimiFrog was guided by the following main criteria:  respectable processing power — significantly higher than any 8-bit or entry-level 32-bit micro-controller, very low energy consumption,... read more

La BlueFrog changes name !

That’s right ! La BlueFrog becomes LimiFrog. Not an easy decision, because I rather liked that name and people were getting used to it. But there were a number of issues. First, from an internet search optimization point of view, it you typed BlueFrog in one... read more

“Maker of Merit” at MFP2015 !

Last Saturday and Sunday,   La BlueFrog’s was holding its first significant exhibition, at Maker Faire Paris 2015. For its second edition, it had significantly grown in size with close to 200 Exhibitors and, reportedly, 35,000 visitors over the 2 days. And, of... read more


Some enclosures for La BlueFrog, all 3D-printed, one kind to accomodate the OLED display, one kind for applications that don’t need a display. Also tried different colors… The opening in the bottom left corner is for the VL6080X ambient light sensor and... read more

BlueTooth 4.1 in action

Too busy with full board validation lately…  Just a quick snapshot of La BlueFrog exchanging with an iPad, using BlueTooth Smart wireless transmission (also known as BlueTooth Low-Energy, a.k.a BTLE, a.k.a BlueTooth 4.x …anyone’s got an idea for more... read more

Testing the Proximity Detector

Here’s a short clip showing one of the unitary tests carried out to validate La BlueFrog V2. It’s a test of the VL6180X ambient light sensor and proximity/distance detector, based on ST’s “FlightSense” technology. The VL6180X is the small... read more

At last !

I received the first samples of La BlueFrog V2 about a week ago ! (sorry, no time to blog about it earlier :-). Perhaps unsurprisingly, it took longer to obtain than anticipated. PCB fabrication had started slowly because the PCB fab shop was closed for several days... read more

Around the Cube

If you want to use La BlueFrog the easy way, it’ll come with an API (Application Programming Interface) that will free you from having to initialize the board (like configuring the GPIOs of the STM32 or configuring the on-chip I2C engine) and will allow you to... read more

La BlueFrog in the making

Hey, I’ve got some nice pictures of La BlueFrog being fabricated ! They’re photos of the board at some strategic manufacturing steps. I thought I’d include them within a quick rundown on the PCB fabrication process. Note it’s a simplified... read more


What can we wish you for 2015 ?  How about this: Great fun with old and new friends.   New experiences and discoveries.   Lots of creativity.   Taking the first steps to make your dreams come true and never regret it. La BlueFrog wishes you a fantastic year 2015 !... read more

Selecting the chips

So, how were the chips used in La BlueFrog selected ? Well, basically it’s been a combination of the following criteria: > minimum footprint (i.e., board real estate consumed), > simple, digital interfacing – for sensors, I2C preferred (as all I2C... read more

Go !

Done! After long days and a few short nights to finalize and check and fix and re-check the design, La BlueFrog V2 was released to PCB shop for fabrication a few days ago. There are almost 100 components on the board in total — from the very basic (resistors,... read more

What the …cap ?!?

Hey, I’ve been away from the blog for too long ! (…so busy finishing up the layout and verifications of La BlueFrog V2). Anyway — a quick (very) techy one. Promised, next post is lighter — it’s some good news too, and it’ll be there... read more

VL6180X – at light speed !

A recent evolution of the specifications for La BlueFrog was the replacement of the Ambient Light Sensor by the VL6180X from ST. What’s this guy ? It’s a Proximity and Distance Detector — and it also embeds the ambient light sensing function, by the way.... read more

La BlueFrog in Paris

On October 29th I was lucky enough to get invited to the “Embedded Day” at Epitech Paris — along with some slightly more well-known names such as ST Micro and Intel (!), plus a couple of other companies. Epitech is a school that specializes in... read more