SBAA607A December   2023  – January 2024 AM2631 , AM2631-Q1 , AM2632 , AM2632-Q1 , AM2634 , AM2634-Q1 , AM263P4 , AMC1303M2520 , AMC1305L25 , AMC1306M25 , TMS320F280033 , TMS320F280034 , TMS320F280034-Q1 , TMS320F280036-Q1 , TMS320F280036C-Q1 , TMS320F280037 , TMS320F280037-Q1 , TMS320F280037C , TMS320F280037C-Q1 , TMS320F280038-Q1 , TMS320F280038C-Q1 , TMS320F280039 , TMS320F280039-Q1 , TMS320F280039C , TMS320F280039C-Q1 , TMS320F280040-Q1 , TMS320F280040C-Q1 , TMS320F280041 , TMS320F280041-Q1 , TMS320F280041C , TMS320F280041C-Q1 , TMS320F280045 , TMS320F280048-Q1 , TMS320F280048C-Q1 , TMS320F280049 , TMS320F280049-Q1 , TMS320F280049C , TMS320F280049C-Q1 , TMS320F28075 , TMS320F28075-Q1 , TMS320F28076 , TMS320F28374D , TMS320F28374S , TMS320F28375D , TMS320F28375S , TMS320F28375S-Q1 , TMS320F28376D , TMS320F28376S , TMS320F28377D , TMS320F28377D-Q1 , TMS320F28377S , TMS320F28377S-Q1 , TMS320F28378D , TMS320F28378S , TMS320F28379D , TMS320F28379D-Q1 , TMS320F28379S , TMS320F28384D , TMS320F28384D-Q1 , TMS320F28384S , TMS320F28384S-Q1 , TMS320F28386D , TMS320F28386D-Q1 , TMS320F28386S , TMS320F28386S-Q1 , TMS320F28388D , TMS320F28388S , TMS320F28P650DH , TMS320F28P650DK , TMS320F28P650SH , TMS320F28P650SK , TMS320F28P659DH-Q1 , TMS320F28P659DK-Q1 , TMS320F28P659SH-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Design Challenge With Digital Interface Timing Specifications
  6. 3Design Approach With Clock Edge Delay Compensation
    1. 3.1 Clock Signal Compensation With Software Configurable Phase Delay
    2. 3.2 Clock Signal Compensation With Hardware Configurable Phase Delay
    3. 3.3 Clock Signal Compensation by Clock Return
    4. 3.4 Clock Signal Compensation by Clock Inversion at the MCU
  7. 4Test and Validation
    1. 4.1 Test Equipment and Software
    2. 4.2 Testing of Clock Signal Compensation With Software Configurable Phase Delay
      1. 4.2.1 Test Setup
      2. 4.2.2 Test Measurement Results
    3. 4.3 Testing of Clock Signal Compensation by Clock Inversion at MCU
      1. 4.3.1 Test Setup
      2. 4.3.2 Test Measurement Results
        1. 4.3.2.1 Test Result – No Clock Inversion of Clock Input at GPIO123
        2. 4.3.2.2 Test Result – Clock Inversion of Clock Input at GPIO123
    4. 4.4 Digital Interface Timing Validation by Calculation Tool
      1. 4.4.1 Digital Interface With No Compensation Method
      2. 4.4.2 Commonly Used Method - Reduction of the Clock Frequency
      3. 4.4.3 Clock Edge Compensation With Software Configurable Phase Delay
  8. 5Conclusion
  9. 6References
  10. 7Revision History

4.3.2 Test Measurement Results

The TMS320F28379D was running an internal TI SDFM software project, where the two GPIOs GPIO122 and GPIO123 are configured for SDFM mode. The SDFM filter is configured for Sinc3 and OSR™ 64 filter. The Sinc3 OSR64 filter outputs a 16-bit two’s complement integer number with a maximum full-scale range from +16384 to -16384.

To conduct the test, two 90-degree phase shifted 10-MHz clock signals with a 50% duty cycle are fed into GPIO123 (SD1_C1) and GPIO122 (SD1_D1) respectively. Note that the AMC1306EVM DOUT data bitstream only changes on the rising clock edge, hence once per clock cycle. For this test the SD1_D1 data toggles between 0 and 1 at every half clock cycle. This is different than the AMC1306EVM DOUT data signal, which changes at every clock cycle.

Due to applying this specific test signal, the input data at GPIO122 (SD1_D1) is always logic ‘1’ at the rising clock edge of GPIO123 and always logic ‘0’ at the falling edge. Hence the output of the Sinc3 filter with OSR 64 filter depends on which clock edge the test data is sampled in the SDFM and the Sinc3 OSR 64 filter output is either 16384 (always sampling ‘1’) if there is no clock inversion at GPIO123 and -16384, if there is a clock inversion at GPIO123 (always sampling ‘0’).