PSI - Issue 43

Dagmar Faktorová et al. / Procedia Structural Integrity 43 (2023) 288–293 Author name / Structural Integrity Procedia 00 (2022) 000 – 000

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Fig. 2. Block diagram of the impedance converter in a two-electrode arrangement (analog parts are marked by red color).

If there is the need to measure the impedance at the zero potential, the analyzer must be supplemented with additional auxiliary circuits, e.g. see Faktorová et al. (2016), because the analyze r circuit in this basic form does not allow control the output voltage DC component. The current consumption of the circuit during the measurement is up to 25 mA. 3 Impedance analyzer based on the STM32 microcontroller For distributed data collection and environmental monitoring in IoT applications and for specific applications it is appropriate to implement the impedance analyzer directly on the chip of a modern universal microcontroller (MCU). Such a solution containing a complete system of measurement and data processing, together with communication circuits in a miniature design allows the use of the analyzer in outdoor and in-situ data collection in the monitored environment directly. The microcontroller not only controls the entire measurement process, but also process the data, controls other peripherals, stores data on a medium and also communicates with the parent system. For the reference implementation of the impedance analyzer, the ARM STM32 L4 Series platform, which enables the construction of the devices with very low power consumption was chosen. 3.1 Signal generator A known direct digital synthesis (DDS) algorithm was used to implement the tunable harmonic signal generator, see Symons (2013). Block diagram of DDS implementation on microcontroller is shown in Fig. 3.

Fig. 3. Block diagram of DDS generator on microcontroller chip.