25fa25a5a9
As there is no check (yet!) in the directive, many .. zephyr-app-commands:: in the documentation are pointing to non-existing sample applications, which is problematic for users who typically expect to just copy-paste the commands and have them work. This commit fixes all offending references to point to existing samples, or converts them to simple ":app:" instead of ":zephyr-app:" when the intent wasn't to refer to in-tree samples. Signed-off-by: Benjamin Cabé <benjamin@zephyrproject.org>
64 lines
2.3 KiB
ReStructuredText
64 lines
2.3 KiB
ReStructuredText
.. zephyr:code-sample:: cmsis-dsp-moving-average
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:name: CMSIS-DSP moving average
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Use the CMSIS-DSP library to calculate the moving average of a signal.
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Overview
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********
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This sample demonstrates how to use the CMSIS-DSP library to calculate the moving average of a
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signal.
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It can be run on any board supported in Zephyr, but note that CMSIS-DSP is specifically optimized
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for ARM Cortex-A and Cortex-M processors.
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A **moving average** filter is a common method used for smoothing noisy data. It can be implemented
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as a finite impulse response (FIR) filter where the filter coefficients are all equal to 1/N, where
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N is the number of "taps" (i.e. the size of the moving average window).
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The sample uses a very simple input signal of 32 samples, and computes the moving average using a
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"window" of 10 samples. The resulting output is computed in one single call to the ``arm_fir_q31()``
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CMSIS-DSP function, and displayed on the console.
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.. note::
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In order to allow an easy comparison of the efficiency of the CMSIS-DSP library when used on ARM
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processors vs. other architectures, the sample outputs the time and number of cycles it took to
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compute the moving average.
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Requirements
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************
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CMSIS-DSP is an optional module and needs to be added explicitly to your Zephyr workspace:
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.. code-block:: shell
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west config manifest.project-filter -- +cmsis-dsp
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west update cmsis-dsp
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Building and Running
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*********************
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The demo can be built as follows:
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.. zephyr-app-commands::
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:zephyr-app: samples/modules/cmsis_dsp/moving_average
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:host-os: unix
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:board: qemu_cortex_m0
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:goals: run
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:compact:
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The sample will output the number of cycles it took to compute the moving averages, as well as the
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computed average for each 10-sample long window of the input signal.
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.. code-block:: console
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*** Booting Zephyr OS build v3.6.0-224-gb55824751d6c ***
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Time: 244 us (244 cycles)
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Input[00]: 0 0 0 0 0 0 0 0 0 0 | Output[00]: 0.00
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Input[01]: 0 0 0 0 0 0 0 0 0 1 | Output[01]: 0.10
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Input[02]: 0 0 0 0 0 0 0 0 1 2 | Output[02]: 0.30
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Input[03]: 0 0 0 0 0 0 0 1 2 3 | Output[03]: 0.60
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...
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Input[30]: 21 22 23 24 25 26 27 28 29 30 | Output[30]: 25.50
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Input[31]: 22 23 24 25 26 27 28 29 30 31 | Output[31]: 26.50
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