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doc: gpio glitch filter

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morris
2022-11-09 16:11:36 +08:00
parent 62f1cbca2c
commit 8277a8e8df
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docs/en/api-reference/peripherals/gpio.rst
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@@ -21,6 +21,36 @@ GPIO Summary
:SOC_ULP_SUPPORTED: - The :doc:`Ultra Low Power co-processor <../../api-reference/system/ulp>` is running
- Analog functions such as ADC/DAC/etc are in use.
.. only:: SOC_GPIO_SUPPORT_PIN_GLITCH_FILTER or SOC_GPIO_FLEX_GLITCH_FILTER_NUM
GPIO Glitch Filter
------------------
The {IDF_TARGET_NAME} chip features hardware filters to remove unwanted glitch pulses from the input GPIO, which can help reduce false triggering of the interrupt and prevent a noise being routed to the peripheral side.
.. only:: SOC_GPIO_SUPPORT_PIN_GLITCH_FILTER
Each GPIO can be configured with a glitch filter, which can be used to filter out pulses shorter than **two** sample clock cycles. The duration of the filter is not configurable. The sample clock is the clock source of the IO-MUX. In the driver, we call this kind of filter as "pin glitch filter". You can create the filter handle by calling :cpp:func:`gpio_new_pin_glitch_filter`. All the configurations for a pin glitch filter are listed in the :cpp:type:`gpio_pin_glitch_filter_config_t` structure.
- :cpp:member:`gpio_pin_glitch_filter_config_t::gpio_num` sets the GPIO number to enable the glitch filter.
.. only:: SOC_GPIO_FLEX_GLITCH_FILTER_NUM
{IDF_TARGET_FLEX_GLITCH_FILTER_NUM:default="8"}
{IDF_TARGET_NAME} provides {IDF_TARGET_FLEX_GLITCH_FILTER_NUM} flexible glitch filters, whose duration is configurable. We refer to this kind of filter as "flex flitch filter". Each of them can be applied to any input GPIO. However, applying multiple filters to the same GPIO doesn't make difference from one. You can create the filter handle by calling :cpp:func:`gpio_new_flex_glitch_filter`. All the configurations for a flexible glitch filter are listed in the :cpp:type:`gpio_flex_glitch_filter_config_t` structure.
- :cpp:member:`gpio_flex_glitch_filter_config_t::gpio_num` sets the GPIO that will be applied the flex glitch filter.
- :cpp:member:`gpio_flex_glitch_filter_config_t::window_width_ns` and :cpp:member:`gpio_flex_glitch_filter_config_t::window_thres_ns` are the key parameters of the glitch filter. During :cpp:member:`gpio_flex_glitch_filter_config_t::window_width_ns`, any pulse whose width is shorter than :cpp:member:`gpio_flex_glitch_filter_config_t::window_thres_ns` will be discarded. Please note that, you can't set :cpp:member:`gpio_flex_glitch_filter_config_t::window_thres_ns` bigger than :cpp:member:`gpio_flex_glitch_filter_config_t::window_width_ns`.
.. only:: SOC_GPIO_SUPPORT_PIN_GLITCH_FILTER and SOC_GPIO_FLEX_GLITCH_FILTER_NUM
Please note, the "pin glitch filter" and "flex glitch filter" are independent. You can enable both of them for the same GPIO.
The glitch filter is disabled by default, and can be enabled by calling :cpp:func:`gpio_glitch_filter_enable`. To recycle the filter, you can call :cpp:func:`gpio_del_glitch_filter`. Please note, before deleting the filter, you should disable it first by calling :cpp:func:`gpio_glitch_filter_disable`.
Application Example
-------------------
@@ -40,3 +70,11 @@ API Reference - Normal GPIO
.. include-build-file:: inc/rtc_io.inc
.. include-build-file:: inc/rtc_io_types.inc
.. only:: SOC_GPIO_SUPPORT_PIN_GLITCH_FILTER or SOC_GPIO_FLEX_GLITCH_FILTER_NUM
API Reference - GPIO Glitch Filter
----------------------------------
.. include-build-file:: inc/gpio_filter.inc