• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Answers 1 answer
  • Subscribers 82 subscribers
  • Views 1233 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

TMS320F28377D - Sigma Delta Filter Module (SDFM), mode 2: Manchester encoded input: Is the mode-2 intended to receive a digital communication data?

Hideaki Nambu
Mastermind 9165 points
Other Parts Discussed in Thread: ADS1203

Hello,

This question came from "TMS320F28377D - Sigma Delta Filter Module (SDFM), mode 2: Manchester encoded input: Any tools to evaluate the mode?"

I understood that "SDFM mode 2" looks good to be connected with ADS1203 and measure the time ratio of input-voltage-high.

[Q1]  Is the mode-2 intended to receive a digital communication data? For example, 40 bytes of manchester encoded data.

[Q2]  Does any interrupt occur when the SDCTLPARM1.MSx bit has a new data ?

Best regards,
-n

  • 0
    TI__Expert 8510 points
    The Manchester-encoded input carries both digital data and the associated clock on the same wire.
    The data carried is the same Sigma-Delta bitstream that would typically be sent using the other modes.
    You can can think of SD bits as carrying the analog value through the density of 1s. To get higher than
    just this 1-bit resolution requires some low-pass filtering, which of course why we have the SDFM
    so that this doesn't have be done by the main CPU.

    The resolution of the data produced by the SDFM and how often it is output is controlled by the OSR
    (Oversample Ratio) of the filter. The OSR for the primary data channel is typically in the range of 32-256
    which can deliver up to 12+ bits ENOB. (Limited by a number of factors including the resolution of the
    source modulator).

    The SDCTLPARMx.MSx bits are supposed to indicate the status of the Manchester encoding (in other
    words, whether the SDFM has successfully been calibrated to the incoming stream and is reliably receiving
    data). The SDFM Interrupt unit can be configured to trigger an interrupt if this calibration fails
    (by enabling the MFx bits), but NO interrupt will occur just because the SDCTLPARMx.MSx bits have new
    data. In practice, you would use the Interrupt unit to generate an interrupt whenever new SDFM
    data is available from the primary (as opposed to secondary/comparator) filter. The AFx bits can be
    set to generate that interrupt. (AFx= Acknowledge /new-data flag). The rate of data from the filter
    will be according to the equation F(data) = F(Manchester data rate) / OSR where F(Manchester) is
    the rate of the actual DATA, not the rate of the incoming transitions (which is higher, since you also
    have the clock transitions merged with the data).
  • 0
    TI__Expert 8510 points
    The Manchester-encoded input carries both digital data and the associated clock on the same wire.
    The data carried is the same Sigma-Delta bitstream that would typically be sent using the other modes.
    You can can think of SD bits as carrying the analog value through the density of 1s. To get higher than
    just this 1-bit resolution requires some low-pass filtering, which of course why we have the SDFM
    so that this doesn't have be done by the main CPU.

    The resolution of the data produced by the SDFM and how often it is output is controlled by the OSR
    (Oversample Ratio) of the filter. The OSR for the primary data channel is typically in the range of 32-256
    which can deliver up to 12+ bits ENOB. (Limited by a number of factors including the resolution of the
    source modulator).

    The SDCTLPARMx.MSx bits are supposed to indicate the status of the Manchester encoding (in other
    words, whether the SDFM has successfully been calibrated to the incoming stream and is reliably receiving
    data). The SDFM Interrupt unit can be configured to trigger an interrupt if this calibration fails
    (by enabling the MFx bits), but NO interrupt will occur just because the SDCTLPARMx.MSx bits have new
    data. In practice, you would use the Interrupt unit to generate an interrupt whenever new SDFM
    data is available from the primary (as opposed to secondary/comparator) filter. The AFx bits can be
    set to generate that interrupt. (AFx= Acknowledge /new-data flag). The rate of data from the filter
    will be according to the equation F(data) = F(Manchester data rate) / OSR where F(Manchester) is
    the rate of the actual DATA, not the rate of the incoming transitions (which is higher, since you also
    have the clock transitions merged with the data).