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RM42L432: Using N2HET to measure 60Hz zero crossings

Jake Lester
Prodigy 20 points
Part Number: RM42L432
Other Parts Discussed in Thread: HALCOGEN

Hello,

I am very new to the Hercules platform. I am in the middle of trying out the Hercules for a prototype which involves measuring 60Hz zero crossings. I have done this before with slower 8-bit controllers with no problem but I'm having a problem figuring out how to do it with this chip. Is there a way that I can get the N2HET timing system to go slow enough that the Loop Resolution will be about 10ms? If I understand correctly, that would be how I would have to do this. On 60Hz, pulses would come at every zero, so they are ~9 ms apart from one another, and the timer system would need to see two pulses within the same loop time for it to know the difference between them, correct? 

Sorry if this is a dumb question. I'm trying to figure it out with HALCoGen, but the interface is all distorted on my computer and it makes it hard to see what is really there and what isn't. 

Thanks

  • 0
    TI__Guru**** 186196 points

    Hello Jake,

    HALCoGen has this architecture limitation and can only be used with 100% font size.

    The NHET can be used to capture the input pulses. There are several timing requirements for input signals in order to be captured correctly by N2HET. The period of the input signal should be less than <2^25*hr*lr*t(vclk2). There is no problem to measure 60Hz signal. The event can be rising edge or falling edge, but the zero crossing.