Other Parts Discussed in Thread: AMC1305L25
Tool/software: Code Composer Studio
Hello
I have a question during the example operation.
example = fcl_f2838x_tmdxiddk_cpu1.project
(use : tmdxiddk279d (Motor driver eval) , tms320f28388 control card (mcu eval) )
In the SDFM setting function filter settings.
OSR = 128 , sinc3 , shift bit = 7
Referenced TRM., I know that.
However, the example uses 6 bits. (source code below.)
Why is it different?
// ******************************************************
// Sinc filter Module
// ******************************************************
// Configure Data filter module's filter type, OSR value and enable /
// disable data filter.
// 16 bit data representation is chosen for OSR 128 using Sinc3, from
// the table in the TRM.
// The max value represented for OSR 128 using sinc 3
// is +/-2097152 i.e. 2^21.
// To represent this in 16 bit format where the first bit is
// sign shift by 6 bits.
SDFM_enableFilter(SDFM1_BASE, (SDFM_FilterNumber)flt);
SDFM_setFilterType(SDFM1_BASE, (SDFM_FilterNumber)flt,
SDFM_FILTER_SINC_3);
SDFM_setFilterOverSamplingRatio(SDFM1_BASE, (SDFM_FilterNumber)flt,127);
//COSR = 127 +1 -> OSR = 128
SDFM_setOutputDataFormat(SDFM1_BASE, (SDFM_FilterNumber)flt,SDFM_DATA_FORMAT_16_BIT);
SDFM_setDataShiftValue(SDFM1_BASE, (SDFM_FilterNumber)flt,6);
//OSR = 128, SINC3 , 6? TRM = 7;
