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