The final target of this project is to have a simple to use ("press a button to start") data logging device, featuring both analog and digital readings. The analog reading will be low voltage (up to 400V) and the digital readings up to 24V.
I plan to offer a small LCD screen to basic data visualization (nokia 5110 display, for example) and a microSD card slot for saving data. The logging interval will be configurable, and I will try and see if I can get times down to 0,1 seconds.
I have decided to start designing the voltage analog inputs' circutry for the datalogger; I will not worry with current inputs or themocouple inputs for now, since I have not even validated the basic concept :) . That's work for the future.
I have selected 3 ranges of voltage input to begin working on: 5V, 50V and 400V (DC). Every range will have an opamp circuit (picture below) to adjust gains and voltage levels. The signal 'V1' in the very left is the input voltage and signal 'V7' is the voltage being applied to the controller (Teensy LC).
The first stage is an inverter and multiplier, which makes a 0-3.3V into a 0.165V-1.65, while the second stage transforms the prior voltage into a 0.3-3V for the Teensy LC analog input.
I will keep you posted on advances I make and new features I implement!.
So guys, welcome to the Teensy data logging project!
What I have done in the first hour (literally) of project is set up a basic sketch to read data from an analog input (A5, pin 19 of Teensy LC) and store it to a micro SD card (on a Catalex breakout board) and send the same data over Serial to the Arduino console (on my PC). No worries and no problems at all, so far.
You guys can check the (rather basic) code on my Github page, linked in the proper section of this hackaday entry.