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resources:tools-software:sigmastudio:toolbox:filters:firfilter [12 Jun 2020 01:00] – Added python example code Joshua Berlinresources:tools-software:sigmastudio:toolbox:filters:firfilter [16 Jun 2020 03:15] (current) – Minor clarifications Joshua Berlin
Line 64: Line 64:
          
 print_object_property('FIR1', 'Coefficients', 0, 0) print_object_property('FIR1', 'Coefficients', 0, 0)
 +</code>
 +
 +====== Controlling the FIR Filter from a Microcontroller ======
 +The following assumes you have a working microcontroller platform, with SigmaDSP interface code based on [[resources:tools-software:sigmastudio:tutorials:microcontroller|Interfacing SigmaDSP Processors with a Microcontroller]].
 +
 +
 +
 +===== Reading FIR Coefficients from the SigmaDSP =====
 +<code cpp>
 +// NOTE: This code will not work for very large filters that span multiple data memories or memory pages.
 +void print_FIR_coeffs(int fir_start_addr, int fir_filter_length) {
 +    // Initialize a double array to hold the coefficients.
 +    double fir_coeffs[fir_filter_length] = {};
 +
 +    for (int i = 0; i < fir_filter_length; i++) {
 +        // DSP memory holds FIR coefficients in reverse order so fill the fir_coeffs array from last to first.
 +        fir_coeffs[fir_filter_length - i - 1] = SIGMA_READ_REGISTER_FLOAT(fir_start_addr + i);
 +    }
 +
 +    // At this point you can do anything you like with fir_coeffs. We will simply print them out.
 +    Serial.println("FIR Coefficients:");
 +    for (int i = 0; i < fir_filter_length; i++) {
 +        Serial.println(fir_coeffs[i], 4);
 +    }
 +}
 +</code>
 +
 +===== Writing FIR Coefficients to the SigmaDSP =====
 +<code cpp>
 +// NOTE: This code will not work for very large filters that span multiple data memories or memory pages.
 +void write_FIR_coeffs(int fir_start_addr, int fir_filter_length, double* coefficients) {
 +    for (int i = 0; i < fir_filter_length; i++) {
 +        // DSP memory holds FIR coefficients in reverse order, so increment address while decrementing coefficient index.
 +        SIGMA_WRITE_REGISTER_FLOAT(fir_start_addr + i, coefficients[fir_filter_length - i - 1]);
 +    }
 +}
 +</code>
 +
 +===== Example Usage =====
 +If you have an FIR algorithm added to your SigmaStudio project, the exported source code will include variable information in the *PARAMS.h* file. Using these variables for addressing allows your code to automatically keep track of any changes in the filter address as your SigmaStudio project grows in complexity.
 +
 +<code cpp>
 +// Print the coefficients contained in the default program
 +print_FIR_coeffs(MOD_FIR1_ALG0_FIRSIGMA300ALG1FIRCOEFF0_ADDR, MOD_FIR1_COUNT);
 +// Create an array of new coefficients
 +double new_coefficients[MOD_FIR1_COUNT] = {0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0};
 +// Write the new FIR coefficients to the DSP
 +write_FIR_coeffs(MOD_FIR1_ALG0_FIRSIGMA300ALG1FIRCOEFF0_ADDR, MOD_FIR1_COUNT, new_coefficients);
 +// Read back the coefficients; they should now be identical to new_coefficients
 +print_FIR_coeffs(MOD_FIR1_ALG0_FIRSIGMA300ALG1FIRCOEFF0_ADDR, MOD_FIR1_COUNT);
 </code> </code>
resources/tools-software/sigmastudio/toolbox/filters/firfilter.txt · Last modified: 16 Jun 2020 03:15 by Joshua Berlin

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