SPRUHX5I August 2014 – May 2024 TMS320F28374S , TMS320F28375S , TMS320F28375S-Q1 , TMS320F28376S , TMS320F28377S , TMS320F28377S-Q1 , TMS320F28378S , TMS320F28379S
Primary (data) filters can be synchronized with respect to the PWM event (called SDSYNC event). The SDSYNC signal from the PWM module is used to reset the DOSR counter. This feature is by default disabled and can be enabled by setting SDDFPARMx.SDSYNCEN = 1. Figure 13-8 shows how the PWM signals are connected to the sigma delta module. In this device, PWM11 can be used to reset SDFM1 filter modules and PWM12 can be used to reset SDFM2 modules.
Because of the inherent architecture of the Sinc filter (Sinc1, Sinc2, Sinc3, SincFast), the first few samples, depending upon filter type, are incorrect. Table 13-5 shows the number of incorrect samples on the following conditions:
Filter Type | Number of Incorrect Samples After the Filter is Enabled and Configured |
---|---|
Sinc1 | No incorrect sample. |
Sinc2 | The first sample of the Sinc2 filter is incorrect. |
SincFast | The first two samples of the SincFast filter are incorrect. |
Sinc3 | The first two samples of the Sinc3 filter are incorrect. |