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MSP430F67791A: Modifying the source code

Prafulla Salunke
Intellectual 660 points
Part Number: MSP430F67791A
Other Parts Discussed in Thread: MSP430F6779, TIDM-AUX-MODULE

Hii,

    I am facing issue while configuring interrupt generation for free running timer. I am using 3 phase EVM with online code available (EVM430-F6779. But i am not able to trace out settings in source code (http://www.ti.com/lit/zip/slaa577. 

    Kindly suggest me the steps to find so.

  • 0
    TI__Mastermind 49692 points
    Hello Praful,

    Which timer are you wanting to use? I suspect that you're trying to configure a module that's already being used. In IAR, I'd recommend using the search feature to look through the project files for the timer that you want to use. Take a look at the 'emeter-setup.c' and 'emeter-structs.h' files as well.

    Regards,

    James

    MSP Customer Applications
  • 0
    TI__Mastermind 49692 points
    Hello Praful,

    Were you able to figure out the issue?

    Regards,

    James

    MSP Customer Applications
  • 0 in reply to James Evans
    Intellectual 660 points

    Hello ,

    I have some queries as on working on MSP430F67791A

    1.  I have refered the EVM code   . It uses 32khz crystal and  has a fsystem of  16MHz  obtained by using FLL ratio of 512. Whether the inaccuracy  of the clock remains same over the Temperature range.

    2. I need to use Hardware multiplier ,but whats the case if  during multiplication Interrupt occurs which further has used the Hardware multiplier block. Will the previous multiplication resume

    3. If i would use ADC with internal reference will be the accuracy over the temperature range be maintained .

  • 0 in reply to Prafulla Salunke
    TI__Mastermind 49692 points

    Hello Praful,

    praful salunke said:
    1.  I have refered the EVM code   . It uses 32khz crystal and  has a fsystem of  16MHz  obtained by using FLL ratio of 512. Whether the inaccuracy  of the clock remains same over the Temperature range.

    By default, the external crystal XT1 is used for the FLL. You'd have to check the specifications and performance information provided by the crystal manufacturer you've selected. For the internal DCO, Table 5-5 specifies that the DCO frequency temperature drift is typically 0.1%/C. Using the FLL to stabilize the DCO will help reduce influences on the frequency of operation due to temperature and voltage variations.

    praful salunke said:
    2. I need to use Hardware multiplier ,but whats the case if  during multiplication Interrupt occurs which further has used the Hardware multiplier block. Will the previous multiplication resume

    For guidance about using interrupts with the MPY32 module, please refer to Section 25.2.7 in the MSP430x5xx/MSP430x6xx User's Guide.

    Regards,

    James

    MSP Customer Applications

  • 0 in reply to Prafulla Salunke
    TI__Mastermind 49692 points

    praful salunke said:
    3. If i would use ADC with internal reference will be the accuracy over the temperature range be maintained .

    Assuming you're referring to the SD24 ADC, you can find Gain and Offset error in Table 5-42 in the datasheet. For the Gain error temperature coefficient, the units are in ppm/C where ppm is a ten thousandth of one percent of error per degrees Celsius (C). It appears that an external reference achieves lower error than the internal reference (but this would require more components obviously). It's important to calibrate the SD24, and you may need to implement temperature compensation on the conversions depending on your requirements.

    Regards,

    James

    MSP Customer Applications

  • 0 in reply to James Evans
    Intellectual 660 points
    Hello James,
    I am very much thankful t you for your reply. I have already started working as per your instructions. As to work with this chip is totally new for me, can i get software support from TI on following fronts of driver layers:
    1. Fsystem : 16MHz using crystal of 32kHz ( External Crystal oscillator)
    2. Configuration of A free running timer of 1 msec.
    3. UART configured to operate at a Baud rate from 300 bps to 115.2 kbps , 8 bit data , Parity : odd/Even ,Stop bit : 1,2 (external crystal of 32 kHz)
    4. SD24 ADC : Need Continuous ADC interrupt at fixed interval of 100usec .On the ADC interrupt ,all channel reading should be ready
    5. I2C configured at @40kbps
    6. Hardware multiplier considerations
    7. RTC _B configured
    8. Watchdog configured at 100msec
    9. Need details on Brownout (as not clearly mentioned in user manual)
  • 0 in reply to Prafulla Salunke
    TI__Mastermind 49692 points

    Hello Praful,

    praful salunke said:
    I am very much thankful t you for your reply. I have already started working as per your instructions. As to work with this chip is totally new for me, can i get software support from TI on following fronts of driver layers:

    Our MSP430F6779(A)-based reference designs will be the best reference and resource. While their configurations may vary from your requirements, a lot of the architecture is already there and just needs changed. Honestly, I've found it to be the most helpful to open up the projects in IAR and search the entire code using the "Find" feature looking for specific modules and their configurations. Keep in mind that if any changes are made to the source code, you'll need to rebuild all projects in the correct order (starting with the project on the bottom of the project overview window on the left in IAR).

    praful salunke said:
    1. Fsystem : 16MHz using crystal of 32kHz ( External Crystal oscillator)

    Most of our designs run at 16MHz already. Some run at 25MHz. The 32kHz crystal is used by the FLL by default.

    praful salunke said:
    2. Configuration of A free running timer of 1 msec.

    Again, you'd have to search the code to see which timer modules are used. I believe the existing code uses a flag to process data every one second, which depends on the number of samples. If you're sampling at 8192Hz, this would mean that around 1msec has passed when 8 samples have been captured.

    praful salunke said:
    3. UART configured to operate at a Baud rate from 300 bps to 115.2 kbps , 8 bit data , Parity : odd/Even ,Stop bit : 1,2 (external crystal of 32 kHz)

    For most of our designs, UART is implemented at a baud rate of 9600 with 8 bit data, no parity, no stop bit. Keep in mind that an external 32kHz crystal wouldn't be able to provide a baud rate of 115200.

    praful salunke said:
    4. SD24 ADC : Need Continuous ADC interrupt at fixed interval of 100usec .On the ADC interrupt ,all channel reading should be ready

    This interval would require a sampling frequency of around 10kHz. It should be possible, but you may have to decrease your OSR which will reduce the SNR performance. You can use the Group bit (read about it in the User's Guide) to group all the SD24 channels together for a single interrupt.

    praful salunke said:
    5. I2C configured at @40kbps

    Some designs may have I2C, but UART is used primarily. Please refer to our non-metering code examples for I2C sample code.

    praful salunke said:
    6. Hardware multiplier considerations

    The hardware multiplier is used in many of our MSP430F6779(A)-based reference designs.

    praful salunke said:
    7. RTC _B configured

    I've seen code relating to this, but not very familiar with it. Again, I'd recommend looking through the code and reading the User's Guide.

    praful salunke said:
    8. Watchdog configured at 100msec

    This is typically 1 second in our reference designs, but can be changed.

    praful salunke said:
    9. Need details on Brownout (as not clearly mentioned in user manual)

    Please refer to the User's Guide where I'd recommend searching for "brownout". After a quick search, I found several sections that discuss the Brownout Reset (BOR) functionality.

    Regards,

    James

    MSP Customer Applications

  • 0 in reply to James Evans
    Intellectual 660 points
    Dear James,
    Thank you for your reply. For this project, i want to use UART to be configured for baud rate of 300 to 115 kbps. Along with this, i want to use internal RTC only. In case power failure occurs, then coin cell battery will power only AUXVCC3 pin of MSP430F67791A.
    As you mentioned, 32kHz crytal can not be used to support 115kbps Baudrate. Please suggest me on selection of external crystal value that can be used with this application.
  • 0 in reply to Prafulla Salunke
    TI__Mastermind 49692 points
    Hello Praful,

    For RTC and AUXVCCx configurations, please refer to our TIDM-AUX-MODULE TI Design. There are nearly twenty different configurations with code examples along with some very good recommendations on how to use these modules.

    Regarding the 115200 baud rate, I would not recommend using an external crystal for this. You'll want to use the internal DCO for this. If you're planning to use any low power modes (LPMx), keep in mind that the wakeup times for the CPU vary and if too slow, the CPU won't wake up in time to catch the data at higher baud rates like 115200. In general, when sleeping and for clocking the RTC, an external crystal works well.

    Regards,

    James

    MSP Customer Applications

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