I have been recently using Microchip’s PIC32MZ as PIC32MX is scarcely available for my high-end projects. Apart from performance, it’s Analog To Digital Converter section is marvelous. I have managed to successfully store 200000 data points from 6 channels (3 Phase Voltage and Current) at a sampling speed of 10µsec.
PIC32MZ’s 12-bit interleaved ADC with 6 Digital Comparators was a perfect choice for the application. The comparators were used to trigger the event of overvoltage and overcurrent on any one phase. The application also recorded pre and post trigger data so that one can analyze the nature of faults occuring.
The application results at site gave us in-depth understanding of electrical fault characteristics.
Speed matters! 12,00,000 data sets or 24,00,000 data size is a lot. So we used external RAM using PIC32MZ’s PMP module, which I shall take up on another topic. This project is an outcome of enormous brain-storming for find the optimal solution to the problem. It has been a great journey from design to implementation.
From Microchip’s AN2785 –
The PIC32MZ and PIC32MK device families have an advanced Class_1 12-bit ADC with features that
enable them to be interleaved such that the composite ADC through-put rate can far exceed any individual ADC through-put rate. This is possible because each family has anywhere from 5-6 separate Class_1 ADC’s that have independent trigger sources. By interleaving, (i.e. staggering), the trigger events and connecting the target analog signal to multiple interleaved ADC inputs in parallel, it’s possible to achieve the rates listed below in the respective product family tables. Complete lists of ADC selectable high speed throughput rates.
