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MSP430F6779: Fixed or floating point

Part Number: MSP430F6779
Other Parts Discussed in Thread: MSPMATHLIB, EVM430-F6779, MSP430FR5994

Is MSP430F6779 fixed or floating-point based signal processing microcontroller?

Best regards,
Adi

  • Hello Adi,

    MSP430 is fixed point 16 Bit Microcontroller...

    Regards,

    Vikas Chola

  • Hi Vikas,

    What does mean that TI offers Floating Point Math Library for MSP430 series?
    I was looking at MSP430F6779, because energy metering is implemented with this model. In that regard, I wanted to know whether software code is implemented as fixed or floating point.

    Best regards,
    Adi
  • Vikas Chola said:

    MSP430 is fixed point 16 Bit Microcontroller...

    MSP430F6xx is with 20-bit CPUXv2.

  • The first paragraph of SLAU499 (link F6779 product page -> MSPMATHLIB product page) describes the Floating Point Math Library as an improved coding of 12 functions already available in the Standard C Library.

    The Abstract of SLAA577G (from the EVM430-F6779 page) has a link to the source for TI's example Energy Metering application; you can download that and see for yourself what it does.
  • Hello Adi,
    Soli is right..MSP430F6xx is with 20-bit CPUXv2 but majorly mathematical operation executes on 16 bit. MSP430F677x doesn't have hardware floating point support. It has 32 bit multiplier peripheral which helps in fast execution of mathematical functions like for metering RMS calculation and few DSP functions. Regarding floating point library, it is an improved version of software code written for MSP430.

    Regards,
    Vikas Chola
  • Hi Vikas,

    Can I adapt example code from energy metering (implemented by using MSP430F6779) to MSP430FR5994 (LEA)?

    Best regards,
    Adi
  • Hello Adi,
    MSP430F6779 have only 32 Bit Hardware multiplier while MSP430FR5994 has Hardware Multiplier +LEA. You can implement all algorithm of MSP430F6779 and it might be overkill depend on your application requirement. However MSP430F6779 has 24 bit Sigma Delta ADC while MSP430FR5994 has 12 bit ADC so ADC accuracy is much better in MSP430F6779 series. I have seen your other post which might be linked with same application where you are comparing MSP430FR5994 with MSP432 and wish to achieve 0.2% Metering.. MSP432 may be good choice but class 0.2% accuracy will depend on current range.
    You need to select the device based on your current range vs ADC accuracy.

    Regards,
    Vikas Chola
  • Hi Vikas,

    Yes, you are right. In a case I choose MSP430FR5994 I would use external ADC (e.g. 16-bit SD) to achieve the required accuracy. As you can notice, MSP430FR5994 is favorized when data logging is one of the system requirements and the reason why I consider this model.

    Best regards,
    Adi

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