This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

External control of PGA411-Q1 via SPI on EVM?

Other Parts Discussed in Thread: PGA411-Q1

Hello,

I'm not sure if this is the right forum, but there is an MSP430 on the PGA411-Q1 EVM, so let's start here.

Is it possible to control the PGA411-Q1 chip from an external MCU via the SPI bus, instead of using the on-board MSP430? I.e. once we checkout the resolver operation using the supplied GUI and MSP430 firmware, we would like to use the same board, but drive the resolver chip from our own microcontroller via the SPI bus.

Thanks,

Chuck

  • Hello Chuck,

    It's a cruel idea to post on the MSP Forum about removing the MSP430 from another TI solution! I would of course recommend attempting to keep the MSP430 in the design, we can try working with you regarding any doubts or concerns you might have about the current solution.

    The MSP430 is described on this EVM as "used for controlling the PGA411-Q1 device through the I/O pins and a SPI port in addition to receiving digital data in different formats" so it appears to be necessary for much more than SPI communication. However the note below Figure 12 does mention that "The EVM can support faster data capture by omitting the USB-to-SPI circuit (using MSP430)" so it might be possible to omit the SPI peripheral on the MSP430 and still use the GUI to view PGA411-Q1 data. If you plan to remove the MSP430 from the system entirely then you will lose GUI functionality and must take on all of the SPI/data pins with the new MCU, but it is still possible. Since I know very little about this design I've moved this post to the Automotive Forum to rely on their expertise.

    Regards,
    Ryan
  • Thank you for the initial response Ryan!  I will follow-up with notes about the PGA411-Q1 EVM.

    J11 on the EVM provides a header to access most of the digital pins on the PGA411-Q1.  You could use this to access the ORD pins (for the parallel output) or the OUTA/B/Z pins (for the emulated encoder output) on a different MCU while still using the MSP430 and GUI to set the register settings.

    To not use the MSP430 on the EVM, simply don't connect the USB cable.  The MSP430 portion of the circuit is powered off of VBUS from USB, including the level translators used on the digital IOs between the PGA411 and the MSP430.  At that point, use header J11 to connect the needed signals to your controller board.

    -Clancy

  • Thank you Clancy - that is great news.

    And Ryan, don't feel bad, yes we are planning to get rid of the MSP430, but we will be controlling the PGA411 with a TMS570.

    Chuck

  • Hi Clancy, just to verify, if we just wanted to use the SPI pins on J11, to talk to the PGA411 with USB unplugged, would that work?

    Thanks,

    Chuck
  • Yes, that should work. Have you tried this on the EVM yet?
  • I just got the SPI interface up and running (with the USB unplugged). I can see data coming back from the PGA411, so that's a good sign. I don't have the motor spinning, so I'm not expecting to see much of any meaning from the angle and velocity readings. Is there an easy way I can verify I am reading good data...a register with a known value perhaps?

    Thanks
  • Never mind - I see the CRC on the Rx.
  • FYI - we did get the SPI interface up and running on the EVM with the USB unplugged. We are reading the Resolver over SPI from the TMS570LS12 control card in a DRV-8301 kit (we did have to make a mod to the DRV board to allow the TMS570 to be the SPI Master). So far we are reading the Resolver Angle with pretty good results. The Resolver velocity on the other hand seems very noisy. Fortunately for us, the position is much more important. Thanks for the support!