72 lines
1.6 KiB
ReStructuredText
72 lines
1.6 KiB
ReStructuredText
.. _qdec_sensor:
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Quadrature Decoder Sensor
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#########################
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Overview
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********
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This sample reads the value of the counter which has been configured in
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quadrature decoder mode.
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It requires:
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* an external mechanical encoder
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* pin to be properly configured in the device tree
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Building and Running
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********************
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In order to run this sample you need to:
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* enable the quadrature decoder device in your board's DT file or board overlay
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* add a new alias property named ``qdec0`` and make it point to the decoder
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device you just enabled
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For example, here's how the overlay file of an STM32F401 board looks like when
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using decoder from TIM3 through pins PA6 and PA7:
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.. code-block:: dts
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/ {
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aliases {
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qdec0 = &qdec;
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};
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};
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&timers3 {
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status = "okay";
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qdec: qdec {
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status = "okay";
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pinctrl-0 = <&tim3_ch1_pa6 &tim3_ch2_pa7>;
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pinctrl-names = "default";
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st,input-polarity-inverted;
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st,input-filter-level = <FDIV32_N8>;
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st,counts-per-revolution = <16>;
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};
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};
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Sample Output
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=============
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Once the MCU is started it prints the counter value every second on the
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console
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.. code-block:: console
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Quadrature decoder sensor test
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Position = 0 degrees
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Position = 15 degrees
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Position = 30 degrees
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...
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Of course the read value changes once the user manually rotates the mechanical
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encoder.
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.. note::
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The reported increment/decrement can be larger/smaller than the one shown
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in the above example. This depends on the mechanical encoder being used and
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``st,counts-per-revolution`` value.
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