PMU-001 : USB Phasor measurement unit June 2026 project update
We are currently evaluating NXP’s i.MXRT1060 CPU based MCUs as the core of our PMU-001 device.
This product is advantageous as it one of the most capable MCU in terms of raw processing power, while also featuring a FPU.
Additionally, the presence of an Ethernet module with IEEE1588 ptp functionality, gives access to an adjustable free running nanoseconds timer counter with 1 sec rollover. A robust hardware on the fly correction capability allows disciplining the counter using a pps GPS signal or an ethernet based LAN ptp clock.
As for disciplined sampling periods, the periodic interrupt timer (PIT) period can be precisely controlled with a period correction resolution of either 1/24 Mhz or 1/150 Mhz, using the LDVAL register that affects the next period, not the current period, ensuring consistent sampling.
Our analysis shows a 7 sample frame jitter of no more than ±40ns (nominal frame interval being 140 000 ns), thanks to the additional processing power which has the effect of reducing IRQ contention, and the improved disciplining features and overall timing tick resolution.
We are also evaluating an additional high precision temperature probe positioned right under the XTAL to provide ppm correction during GPS holdover intervals, with an intended goal of < 1ppm deviation during GPS holdover intervals. Such a fixture, besides providing TCXO capability without the need of replacing the onboard XTAL, also improve robustness of GPS pps signal outlier filtering, by providing ppm deviation prediction based on temperature slew, provided the temperature measurement is itself low noise. This would help identify the very infrequent but possible GPS pps glitches.
Such level of discipline precision is adequate a field microPMU, which is our intended market segment,
Discarding the requirement for an external OCXO or TCXO driven MCU or sampling timer would drastically lower R&D production, and time to market delays.
At this point in time AD7606 interfacing has been done on the new MCU platform with satisfying results.
Thus, We are now moving our development efforts towards PCB design.
For more information about i.MX-RT1060 and i.MX-RT1060 based MCUs :
https://www.nxp.com/products/i.MX-RT1060
https://www.pjrc.com/store/teensy41.html
Stay tuned !