For my smart watch project I decided to experiment with sensors for reading pulse. Looking around I stumbled upon a sensor made by Maxim – MAX30100. For my surprise once I got my development board and delved into the sensor’s datasheet I discovered it’s not as simple as just wiring up the sensor to a microcontroller and reading the data. A lot of work you have to do yourself. In this tutorial, I’ll try to explain what I’ve learned about pulse oximeter and how to make sense of their data.
nRF51 Makefile with Qt Creator
Recently I assembled a PCB I designed with the latest revision of nRF51822AC, and for my surprise the code I wrote on BLE400 development board just doesn’t work on the new platform. My main concern is that I never really figured out have to use Qt’s QBS to separate compilation of C files with GCC and CPP files with G++.In addition because I don’t properly compile the application, it seems that the G++ screws with the memory addresses regarding C code. Long story short, I realised that Qt Creator can also make use of Makefile directly in the IDE. Best part, it is extremely simple to setup, even with debugging. In this article I will go through what I changed in the nRF51 makefile to be able to compile CPP files and have two versions of release and debug for Qt Creator to compile. If you’re a hardcore compiler and makefile guru, this article probably is not for you.
MEMS (Part 2) – Guide to using gyroscope L3G4200D
For most of the people probably the next step in the world of MEMS is to interface gyroscope. Most likely use gyroscope data to fuse with accelerometer data. If you have implanted acc before, you’ll know that acc is very responsive and noisy when it comes to measuring pitch and roll. It is possible to smooth out the data via sensor fusion. In this tutorial I will explain what data we will be getting from gyroscope, how to use the data to calculate pitch, roll and yaw and finally how to fuse sensor data with complimentary filter.
MEMS (Part 1) - Guide to using accelerometer ADXL345
Recently I’ve been playing with cheap GY-80 module, more precisely 10DOF module with accelerometer, gyroscope, magnetometer and barometer. Eventually I’ll write how to use all four of them. I’ll start with accelerometer (accel). This guide could potentially be used for interfacing most of the MEMS accels, and definitely as a guide how to interpret data coming from the accel, not only from MEMS but also how to use the data coming from Smartphone, wiimote etc. They are basically the same thing. However, I won’t be describing features as tap sensing and double tap sensing, this will be only an introduction about the raw accelerometer.
Programming micro-controller (Arduino) with cheap HC-06 Bluetooth
I and my friend Zenios Agapiou thought of constructing a simple two wheel balancer robot. At the beginning we thought we will just program our Atmega88pa micro-controller through standard JTAG. However, we quickly realized we have Bluetooth connected to the RX/TX device, so we thought whether we can upload Arduino bootloader to the atmega and program it wirelessly. However it wasn’t that simple as we initially anticipated.