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Original question:

PGA411-Q1: fault Dignosed

PGA411-Q1: Faulit Dignosed

Gavin Cloud
Prodigy 70 points
Part Number: PGA411-Q1

Hi,

      Recently in debugging fault diagnosis of PGA411-Q1. Sinusoidal and cosine open circuit faults and short circuit faults cannot be read from the register. Meanwhile,  SFAULT is always set to 1, and the states of

SOUTA and SOUTB always jump constantly  in DEV_STAT4, but the function is normal, I can read the Angle correctly. I can't  find the way to slove this issule.

    Thanks for the support !

  • 0
    TI__Mastermind 23810 points
    First, please note that most of the fault bits are clear on read. If you only see SFAULT, then you must have accidentally already cleared the actual fault bit. You can use FAULTRES to clear faults and try again.

    To get the short circuit and open faults to work, you will need to tighten the thresholds for those diagnostics. For the open fault on the EVM, try changing the SIN/COS gain to 2.25 in addition to tightening the thresholds.

    SOUTA and SOUTB bits are not faults. They are indicators for the current state of the OUTA/OUTB pins, so it is normal for them to be changing when the angle output is changing.
  • 0 in reply to Clancy Soehren
    Prodigy 70 points
    Hi Clancy,
    I feel grateful for your help . I have some trouble in the use of PGA411, like this :

    1)When make the excitation + /excitation- open load , the FOSHORT is set to 1 . At the same time the SFAULT is set to 1.

    2)When make the SIN/COS input open load ，the FLOOPE is set to 1; But the Open load state FOCOSOPL/FOSINOPL/FOCOSOPH/FOSINOPH is 0 . At the same time the SFAULT is set to 1.

    3)When make the COS+ and COS- connect each other , SIN+ and SIN- connect each other, the FOSHORT is set to 1. At the same time the SFAULT is set to 1.But make the COS and SIN connect each other , the FOSHORT is 0 , At the same time the SFAULT is 0.

    4)When make the COS/SIN short to GND , Or short to VCC , Only the SFAULT is set to 1 , the FOSHORT is 0.


    Thanks for the support !
  • 0 in reply to Gavin Cloud
    TI__Mastermind 23810 points
    1) This is expected. In an open exciter condition, the fault will be detected on the SIN/COS side, and it will look like a mutual short condition.
    2) This means that OCOS/OSIN is not crossing the OOPENTH/L threshold. You can fix this by changing the threshold, changing the AFE resistors, or increasing the COSGAIN/SINGAIN.
    3) Cos and sin connected to each-other is difficult to detect. This might be something that needs to be detected in the MCU based on the angle output in such a condition.
    4) When SFAULT is set, another fault bit should always have been triggered. The fault status registers are clear on read, so it is possible to accidentally miss it if you are reading registers multiple times. Also, short to GND is typically detected by the FIZHx and FIZLx fault flags, not FOSHORT.
  • 0 in reply to Clancy Soehren
    Prodigy 70 points
    Hi Clancy,
    Thank you for your help, But there are two questiones that confuse me.

    1) The second issue that i asked you last time , I have increased the the COSGAIN / SINGAIN, But When i make the SIN/COS input open load ， the Open load state FOCOSOPL/FOSINOPL/FOCOSOPH/FOSINOPH is 0 . My register is seted : DEV_AFE_CFG_Reg = 0x0005(GAINCOS:1 ; GAINSIN:1), When i set DEV_AFE_CFG_Reg = 0x000A(GAINCOS:2.25 ; GAINSIN:2.25), PGA411-Q1 is not normal work. Even if I change the OOPENTHL\OOPENTHH , Problems remain.

    2)When make the COS/SIN short to GND, FIZLx of SIN- and SIN+ is same ， FIZLx of COS- and COS+ is same. Even if I change the OVIZL\OVIZH , Problems remain. But When make the COS/SIN short to VCC, FIZHx of of SIN- \ SIN+ \COS- \ COS+ is different.

    Looking forward to your reply !