PGA411Q1EVM: OUTA and OUTB outputs

Manuel Ahumada

Part Number: PGA411Q1EVM
Other Parts Discussed in Thread: PGA411-Q1

Hi,

I got the PGA411-Q1 EVM connected for encoder emulation, and it appears to me that the outputs on OUTA and OUTB may be incorrect. If you notice the attached picture from an oscilloscope, you will notice that the pulses are not consistent (OUTA on the top channel, OUTB on the bottom). For some reason, there seems to be a consistent high pulse every so-often. If you could please advice, I would appreciate it.

Thanks!

over 7 years ago

0 Clancy Soehren over 7 years ago

TI__Mastermind 23810 points

Manuel,

Is the motor rotating at a constant speed, or is this at a stationary angle?

The OUTA/B/Z outputs are a direct output of the PGA411's digital tracking loop, updated at a rate of 10MHz. There is no post processing done to ensure that each step size is exactly even. If you were to look at the parallel or SPI angle output, you would see that they all line up with these OUTA/B/Z signals.

0 Manuel Ahumada over 7 years ago in reply to Clancy Soehren

Prodigy 80 points

Clancy,

Yes, the motor is running at a constant speed.

Hmmm, am I wrong by thinking that the output should look like figure 81 specified in the datasheet (screenshot of figure 81 attached)?

0 Clancy Soehren over 7 years ago in reply to Manuel Ahumada

TI__Mastermind 23810 points

Manuel,

Yes, you should be seeing something closer to that figure. Can you also capture the waveform at AOUT in your setup?

0 Manuel Ahumada over 7 years ago in reply to Clancy Soehren

Prodigy 80 points

That's strange, there isn't much coming out of AOUT. Simply a 3V line..

0 Manuel Ahumada over 7 years ago in reply to Manuel Ahumada

Prodigy 80 points

Clancy,

Well, this is embarrassing, but it turns out that the resolver leads were incorrectly labeled, thus I had them connected to the board incorrectly. Once that got figured out, I was able to recreate figure 81. Sorry about that, but thanks for helping me walk through it.

- Manuel

0 Clancy Soehren over 7 years ago in reply to Manuel Ahumada

TI__Mastermind 23810 points

No problem, I'm glad that you were able to fix the problem!

-Clancy

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PGA411Q1EVM: OUTA and OUTB outputs