6 Application Implementation

The application firmware is developed on a AVR128DA48 microcontroller, generated using:

The MCU peripherals, TIMERs, SPI, USART, ADC, and ZCDs are used to implement the functionalities of the phase sequence detection using a three-phase power supply.

The Timer/Counter type A instance 1 (TCA1) is used for scheduling the tasks every 500 µs; it is configured to generate an interrupt for every 500 µs.

Timer/Counter type A instance 0 (TCA0) is configured to generate an overflow interrupt for every 20 ms. It is used for measuring the time in-between two ZCD interrupts, thereby calculating the phase-shift between the phases of three-phase input.

The SPI is used to integrate the waveform click for generating the three-phase emulated signal; it is configured in Master mode with a 6 MHz SPI clock (SPI_CLK) and a SPI data mode two.

The USART is used for communication between the host computer and application setup; it is configured with a 230400 baud rate.

The ADC is used for reproducing the input signal on the data visualizer (for demonstration) and also for three-phase RMS voltage measurement; it is configured with a 2 MHz ADC_CLK (ADC clock) and 126.3 kHz (0.79 µs) sampling rate.

The two ZCD instances are used for detecting the zero cross of the three-phase input signal; they are configured with interrupt on the rising edge signal.