I use ADE7880. On my design, i need to monitor harmonics. Datasheet suggested using HREADY signal. As i understand in datasheet, the signal is normally on high, when registers uptade, the signals turn low during 10us, after that turn high again. But, i examine to the signal reversed. Normally low, when registers update, it turn high during 10usec.
I added my scope image. I measure signal direct output of ade7880, there is nothing between probe and ade7880.
I try all options about HCONFIG register. CF2DIS bit in CONFIG register is 1.
I hope that i misunderstand HREADY polarity :)
In datasheet Rev C, page 66,
"The default state of this signal is high. Every time the harmonic registers are updated based on HRATE bits in HCONFIG register, the signal HREADY goes low for approx-imately 10 μs and then goes back high."
Yes you are correct I will add this to the change list for the datasheet.
The HREADY goes high for 58.9us at the periodic rate set by HRATE.
I have verified using the eval board and eval software. The high time is constant over all update rates.
Thanks for your reply.
Yes this is my understanding
I have a one more question about harmonics,
In the datasheet, Harmonic engine settle time is described as 750ms.
I want to monitorize all harmonics up to 50th. As i understand, this is impossible to do the task within a reasonable time. Each time, i can monitorize 1 phase's 3 harmonic, after this, i need wait for 750ms. Reading all harmonics takes more than 20second. Can you fix me, if i am wrong? Does Analog Devices have solution for this problem?(maybe other ADE versions)
You are correct . The ADE7880 can only read 3 harmonics at a time on a selected phase. You would have to repeat the harmonic sequence for each phase. The other option you have is waveform samples and do the FFT and calculate the measurements you design. The ADE9000/ADE9078 has a waveform buffer and re-sampling to capture 128/64 points per cycle. All the ADC inputs are captured simultaneously in the buffer making comparisons between phases over the same period of time possible. This is only waveform data and all calculations will have to be done in the microcontroller.