Flash data logger then acquisition data system is designed for long time data acquisition and storage on the SD memory card formatted FAT 32. Acquisition data system may be used for long time data acquisition process parameters with time scale from any seconds to many hours, like chromatography, geophysical measuring, temperature measuring, any parameters monitoring and so on.

Acquisition data system consist from controller with internal ADC, LCD module resolution 128x64 pixels, RAM 32 kb, real time clock, and input amplifiers. Acquisition data system ensures following mode file recording:

To communicate with other electronics, provides a strobe output that accompanies the time of digitizing the input signal.
Input voltage range 0÷1.0 V
The number of multiplexed channels 4
Sampling frequency continuous recording 0,2 Hz ÷ 5 kHz
Sampling frequency mode acquisition/writing 38, 77, 154, 307 kHz
ADC resolution 10 bit
Supply voltage 8÷12 V
Consumption current 90 mA
Input Resistance 10 kOm
The absolute measurement error ±26 mV
Dimension 120x75x70 mm

Schematic diagram:

From the developer.

Flash recorder has been conceived as an alternative to the previously common electromechanical chart recorder. Flash recorder is writing the digitized data on the SD memory card, operating mode of the SPI interface. Developed software code facilitates the recording of data in the FAT32 format. Receiving the digitized data produced by an interrupt, the main loop program performs the search for free sectors on the memory card, the chaining of the clusters and the output of measurements on the screen of the device. Memory card has a built-in controller that executes commands read/write, the run time of one and the same command can vary from 3 to 40 mS. So data is not lost during periods of memory card dummy the device is equipped with a buffer memory of 32 kB. As experience has shown, data collection and recording in the memory card with no gaps works up to 5 kHz. Promising to improve performance, the priority is the communication protocol "SD bus".

Low-budget version of Flash logger is designed with 10-bit built in controller ADC. When the registrar was used with the high-voltage power source, it was found that during high-voltage impulse noise on the supply lines can go and stop real-time clock (RTC). Set the time again leads to the restoration of RTC. In case of the controller hang provides a Watchdog timer that is activated "Autostart mode". Screen with a resolution of 128x64 bits is selected as the low-cost solution, development of the system is represented with 24 bit δ-∑ ADC and TFT color screen.

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