This is just simple voltage logger which writes up to 8 voltages to the text file on a micro SD card. The logger is an ideal solution for applications where small, cheap and simple device is needed to record voltages without any additional hardware. Examples of possible applications are: recording the temperatures using thermocouple amplifiers, measuring a battery voltage for charge and discharge curves, logging weight as voltage from the load cell signal conditioner, etc.

Features

• Easy to use: only one start/stop button and all the settings are stored in configuration text file on the SD card.
• The recorded data is stored in comma separated text file (CSV) and each entry (measurement) has a time stamp in milliseconds.
• Configurable calibration coefficients (gain and zero offset) and moving average filter for each channel.
• Three LEDs for indication of logger state.
• ESD protection of analog inputs.

Specification:

• Power supply voltage: 5V-20V
• Current consumption: 70mA at 5V input
• Number of channels: 8
• Channel input type: Singe-ended
• Input voltage range: 0 … +3.3V
• Sample time: 0.5 ms … 5000 ms (5 sec), 0.2 Hz … 2 kHz
• Measurement accuracy (3-sigma): 3.3 mV (0.1% of full scale) with default 4th order moving average filter
• Input impedance (max): 50 kOhm
• Microcontroller: STM32F405RGT6 (Cortex M4 core)
• PCB size: 48.26 mm x 27.0 mm (1.9 in x 1.063 in)
• Support for up to 32GB micro-SD cards (FAT32), for best results the UHS Speed Class 1 (U1) SD card recommended.

Documentation and download:

• User manual
• Schematic diagram
• Firmware source code (based on ChibiOS 2.6.7 RTOS)
• An example of a log file
• An example of configuration file: 0.5 ms sampling time, all channels enabled and calibrated for voltage recording.
• The Use Case: recording temperature from AD8495 thermocouple amplifier module simultaneously with Extech SDL200 temperature logger, the difference bound is 1°C, here is XLS data

Don't forget to select "With SD card and calibrated" option to get 16Gb SD card with all calibration coefficients for your logger.