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Diffstat (limited to 'Drivers/CMSIS/DSP/Examples/ARM/arm_fir_example/arm_fir_example_f32.c')
| -rw-r--r-- | Drivers/CMSIS/DSP/Examples/ARM/arm_fir_example/arm_fir_example_f32.c | 233 |
1 files changed, 233 insertions, 0 deletions
diff --git a/Drivers/CMSIS/DSP/Examples/ARM/arm_fir_example/arm_fir_example_f32.c b/Drivers/CMSIS/DSP/Examples/ARM/arm_fir_example/arm_fir_example_f32.c new file mode 100644 index 0000000..3dd9f5a --- /dev/null +++ b/Drivers/CMSIS/DSP/Examples/ARM/arm_fir_example/arm_fir_example_f32.c @@ -0,0 +1,233 @@ +/* ----------------------------------------------------------------------
+ * Copyright (C) 2010-2012 ARM Limited. All rights reserved.
+ *
+* $Date: 17. January 2013
+* $Revision: V1.4.0
+*
+* Project: CMSIS DSP Library
+ * Title: arm_fir_example_f32.c
+ *
+ * Description: Example code demonstrating how an FIR filter can be used
+ * as a low pass filter.
+ *
+ * Target Processor: Cortex-M4/Cortex-M3
+ *
+* Redistribution and use in source and binary forms, with or without
+* modification, are permitted provided that the following conditions
+* are met:
+* - Redistributions of source code must retain the above copyright
+* notice, this list of conditions and the following disclaimer.
+* - Redistributions in binary form must reproduce the above copyright
+* notice, this list of conditions and the following disclaimer in
+* the documentation and/or other materials provided with the
+* distribution.
+* - Neither the name of ARM LIMITED nor the names of its contributors
+* may be used to endorse or promote products derived from this
+* software without specific prior written permission.
+*
+* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+* POSSIBILITY OF SUCH DAMAGE.
+ * -------------------------------------------------------------------- */
+
+/**
+ * @ingroup groupExamples
+ */
+
+/**
+ * @defgroup FIRLPF FIR Lowpass Filter Example
+ *
+ * \par Description:
+ * \par
+ * Removes high frequency signal components from the input using an FIR lowpass filter.
+ * The example demonstrates how to configure an FIR filter and then pass data through
+ * it in a block-by-block fashion.
+ * \image html FIRLPF_signalflow.gif
+ *
+ * \par Algorithm:
+ * \par
+ * The input signal is a sum of two sine waves: 1 kHz and 15 kHz.
+ * This is processed by an FIR lowpass filter with cutoff frequency 6 kHz.
+ * The lowpass filter eliminates the 15 kHz signal leaving only the 1 kHz sine wave at the output.
+ * \par
+ * The lowpass filter was designed using MATLAB with a sample rate of 48 kHz and
+ * a length of 29 points.
+ * The MATLAB code to generate the filter coefficients is shown below:
+ * <pre>
+ * h = fir1(28, 6/24);
+ * </pre>
+ * The first argument is the "order" of the filter and is always one less than the desired length.
+ * The second argument is the normalized cutoff frequency. This is in the range 0 (DC) to 1.0 (Nyquist).
+ * A 6 kHz cutoff with a Nyquist frequency of 24 kHz lies at a normalized frequency of 6/24 = 0.25.
+ * The CMSIS FIR filter function requires the coefficients to be in time reversed order.
+ * <pre>
+ * fliplr(h)
+ * </pre>
+ * The resulting filter coefficients and are shown below.
+ * Note that the filter is symmetric (a property of linear phase FIR filters)
+ * and the point of symmetry is sample 14. Thus the filter will have a delay of
+ * 14 samples for all frequencies.
+ * \par
+ * \image html FIRLPF_coeffs.gif
+ * \par
+ * The frequency response of the filter is shown next.
+ * The passband gain of the filter is 1.0 and it reaches 0.5 at the cutoff frequency 6 kHz.
+ * \par
+ * \image html FIRLPF_response.gif
+ * \par
+ * The input signal is shown below.
+ * The left hand side shows the signal in the time domain while the right hand side is a frequency domain representation.
+ * The two sine wave components can be clearly seen.
+ * \par
+ * \image html FIRLPF_input.gif
+ * \par
+ * The output of the filter is shown below. The 15 kHz component has been eliminated.
+ * \par
+ * \image html FIRLPF_output.gif
+ *
+ * \par Variables Description:
+ * \par
+ * \li \c testInput_f32_1kHz_15kHz points to the input data
+ * \li \c refOutput points to the reference output data
+ * \li \c testOutput points to the test output data
+ * \li \c firStateF32 points to state buffer
+ * \li \c firCoeffs32 points to coefficient buffer
+ * \li \c blockSize number of samples processed at a time
+ * \li \c numBlocks number of frames
+ *
+ * \par CMSIS DSP Software Library Functions Used:
+ * \par
+ * - arm_fir_init_f32()
+ * - arm_fir_f32()
+ *
+ * <b> Refer </b>
+ * \link arm_fir_example_f32.c \endlink
+ *
+ */
+
+
+/** \example arm_fir_example_f32.c
+ */
+
+/* ----------------------------------------------------------------------
+** Include Files
+** ------------------------------------------------------------------- */
+
+#include "arm_math.h"
+#include "math_helper.h"
+
+/* ----------------------------------------------------------------------
+** Macro Defines
+** ------------------------------------------------------------------- */
+
+#define TEST_LENGTH_SAMPLES 320
+#define SNR_THRESHOLD_F32 140.0f
+#define BLOCK_SIZE 32
+#define NUM_TAPS 29
+
+/* -------------------------------------------------------------------
+ * The input signal and reference output (computed with MATLAB)
+ * are defined externally in arm_fir_lpf_data.c.
+ * ------------------------------------------------------------------- */
+
+extern float32_t testInput_f32_1kHz_15kHz[TEST_LENGTH_SAMPLES];
+extern float32_t refOutput[TEST_LENGTH_SAMPLES];
+
+/* -------------------------------------------------------------------
+ * Declare Test output buffer
+ * ------------------------------------------------------------------- */
+
+static float32_t testOutput[TEST_LENGTH_SAMPLES];
+
+/* -------------------------------------------------------------------
+ * Declare State buffer of size (numTaps + blockSize - 1)
+ * ------------------------------------------------------------------- */
+
+static float32_t firStateF32[BLOCK_SIZE + NUM_TAPS - 1];
+
+/* ----------------------------------------------------------------------
+** FIR Coefficients buffer generated using fir1() MATLAB function.
+** fir1(28, 6/24)
+** ------------------------------------------------------------------- */
+
+const float32_t firCoeffs32[NUM_TAPS] = {
+ -0.0018225230f, -0.0015879294f, +0.0000000000f, +0.0036977508f, +0.0080754303f, +0.0085302217f, -0.0000000000f, -0.0173976984f,
+ -0.0341458607f, -0.0333591565f, +0.0000000000f, +0.0676308395f, +0.1522061835f, +0.2229246956f, +0.2504960933f, +0.2229246956f,
+ +0.1522061835f, +0.0676308395f, +0.0000000000f, -0.0333591565f, -0.0341458607f, -0.0173976984f, -0.0000000000f, +0.0085302217f,
+ +0.0080754303f, +0.0036977508f, +0.0000000000f, -0.0015879294f, -0.0018225230f
+};
+
+/* ------------------------------------------------------------------
+ * Global variables for FIR LPF Example
+ * ------------------------------------------------------------------- */
+
+uint32_t blockSize = BLOCK_SIZE;
+uint32_t numBlocks = TEST_LENGTH_SAMPLES/BLOCK_SIZE;
+
+float32_t snr;
+
+/* ----------------------------------------------------------------------
+ * FIR LPF Example
+ * ------------------------------------------------------------------- */
+
+int32_t main(void)
+{
+ uint32_t i;
+ arm_fir_instance_f32 S;
+ arm_status status;
+ float32_t *inputF32, *outputF32;
+
+ /* Initialize input and output buffer pointers */
+ inputF32 = &testInput_f32_1kHz_15kHz[0];
+ outputF32 = &testOutput[0];
+
+ /* Call FIR init function to initialize the instance structure. */
+ arm_fir_init_f32(&S, NUM_TAPS, (float32_t *)&firCoeffs32[0], &firStateF32[0], blockSize);
+
+ /* ----------------------------------------------------------------------
+ ** Call the FIR process function for every blockSize samples
+ ** ------------------------------------------------------------------- */
+
+ for(i=0; i < numBlocks; i++)
+ {
+ arm_fir_f32(&S, inputF32 + (i * blockSize), outputF32 + (i * blockSize), blockSize);
+ }
+
+ /* ----------------------------------------------------------------------
+ ** Compare the generated output against the reference output computed
+ ** in MATLAB.
+ ** ------------------------------------------------------------------- */
+
+ snr = arm_snr_f32(&refOutput[0], &testOutput[0], TEST_LENGTH_SAMPLES);
+
+ if (snr < SNR_THRESHOLD_F32)
+ {
+ status = ARM_MATH_TEST_FAILURE;
+ }
+ else
+ {
+ status = ARM_MATH_SUCCESS;
+ }
+
+ /* ----------------------------------------------------------------------
+ ** Loop here if the signal does not match the reference output.
+ ** ------------------------------------------------------------------- */
+
+ if ( status != ARM_MATH_SUCCESS)
+ {
+ while (1);
+ }
+
+ while (1); /* main function does not return */
+}
+
+/** \endlink */
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