ESP32 的 IDF 內 PCNT （Pulse Counter / 脈衝計數器）API 函數模塊用於計算輸入信號的上升沿（Rising Edges）和下降沿（Falling Edges）的數量。函數模塊還可以設定輸入訊號的要求和中斷等等。
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| ESP32 PULSE_CNT 遞增 / 遞減計數圖 |
功能 - pcnt_unit_config
原型：esp_err_t pcnt_unit_config(const pcnt_config_t
*pcnt_config)
參數：pcnt_config: Pointer of Pulse Counter unit
configure parameter
返回：ESP_OK Success
ESP_ERR_INVALID_ARG Parameter error
說明：Configure Pulse Counter unit. This function will
disable three events: PCNT_EVT_L_LIM, PCNT_EVT_H_LIM, PCNT_EVT_ZERO.
範例：
功能 - pcnt_get_counter_value
原型：esp_err_t pcnt_get_counter_value(pcnt_unit_t
pcnt_unit, int16_t *count)
參數：pcnt_unit: Pulse Counter unit number
count: Pointer to accept counter value
返回：ESP_OK Success
ESP_ERR_INVALID_ARG Parameter error
說明：Get pulse counter value.
範例：
功能 - pcnt_counter_pause
原型：esp_err_t pcnt_counter_pause(pcnt_unit_t
pcnt_unit)
參數：pcnt_unit: PCNT unit number
返回：ESP_OK Success
ESP_ERR_INVALID_ARG Parameter error
說明：Pause PCNT counter of PCNT unit.
範例：
功能 - pcnt_counter_resume
原型：esp_err_t pcnt_counter_resume(pcnt_unit_t
pcnt_unit)
參數：pcnt_unit: PCNT unit number, select from
pcnt_unit_t
返回：ESP_OK Success
ESP_ERR_INVALID_ARG Parameter error
說明：Resume counting for PCNT counter.
範例：
功能 - pcnt_counter_clear
原型：esp_err_t pcnt_counter_clear(pcnt_unit_t pcnt_unit)
參數：pcnt_unit: PCNT unit number, select from
pcnt_unit_t
返回：ESP_OK Success
ESP_ERR_INVALID_ARG Parameter error
說明：Clear and reset PCNT counter value to zero.
範例：
功能 - pcnt_intr_enable
原型：esp_err_t pcnt_intr_enable(pcnt_unit_t pcnt_unit)
參數：pcnt_unit: PCNT unit number
返回：ESP_OK Success
ESP_ERR_INVALID_ARG Parameter error
說明：Enable PCNT interrupt for PCNT unit.
Note：Each Pulse counter unit has five watch
point events that share the same interrupt. Configure events with
pcnt_event_enable() and pcnt_event_disable()
範例：
功能 - pcnt_intr_disable
原型：esp_err_t pcnt_intr_disable(pcnt_unit_t pcnt_unit)
參數：pcnt_unit: PCNT unit number
返回：ESP_OK Success
ESP_ERR_INVALID_ARG Parameter error
說明：Disable PCNT interrupt for PCNT unit.
範例：
功能 - pcnt_event_enable
原型：esp_err_t pcnt_event_enable(pcnt_unit_t unit,
pcnt_evt_type_t evt_type)
參數：unit: PCNT unit number
evt_type: Watch point event type. All
enabled events share the same interrupt (one interrupt per pulse counter unit).
返回：ESP_OK Success
ESP_ERR_INVALID_ARG Parameter error
說明：Enable PCNT event of PCNT unit.
範例：
功能 - pcnt_event_disable _div
原型：esp_err_t pcnt_event_disable(pcnt_unit_t unit,
pcnt_evt_type_t evt_type)
參數：unit: PCNT unit number
evt_type: Watch point event type. All
enabled events share the same interrupt (one interrupt per pulse counter unit).
返回：ESP_OK Success
ESP_ERR_INVALID_ARG Parameter error
說明：Disable PCNT event of PCNT unit.
範例：
功能 - pcnt_set_event_value
原型：esp_err_t pcnt_set_event_value(pcnt_unit_t unit,
pcnt_evt_type_t evt_type, int16_t value)
參數：unit: PCNT unit number
evt_type: Watch point event type. All enabled
events share the same interrupt (one interrupt per pulse counter unit).
value: Counter value for PCNT event
返回：ESP_OK Success
ESP_ERR_INVALID_ARG Parameter error
說明：Set PCNT event value of PCNT unit.
範例：
功能 - pcnt_get_event_value
原型：esp_err_t pcnt_get_event_value(pcnt_unit_t unit,
pcnt_evt_type_t evt_type, int16_t *value)
參數：unit: PCNT unit number
evt_type: Watch point event type. All
enabled events share the same interrupt (one interrupt per pulse counter unit).
value:
Pointer to accept counter value for PCNT event
返回：ESP_OK Success
ESP_ERR_INVALID_ARG Parameter error
說明：Get PCNT event value of PCNT unit.
範例：
功能 - pcnt_isr_register
原型：esp_err_t pcnt_isr_register(void (*fn)(void *),
void *arg, int intr_alloc_flags, pcnt_isr_handle_t *handle, )
參數：fn: Interrupt handler function.
arg: Parameter for handler function
intr_alloc_flags: Flags used to allocate
the interrupt. One or multiple (ORred) ESP_INTR_FLAG_* values. See esp_intr_alloc.h
for more info.
handle: Pointer to return handle. If
non-NULL, a handle for the interrupt will be returned here. Calling
esp_intr_free to unregister this ISR service if needed, but only if the handle
is not NULL.
返回：ESP_OK Success
ESP_ERR_NOT_FOUND Can not find the
interrupt that matches the flags.
ESP_ERR_INVALID_ARG Function pointer error.
說明：Register PCNT interrupt handler, the handler is an
ISR. The handler will be attached to the same CPU core that this function is
running on. Please do not use pcnt_isr_service_install if this function was
called.
範例：
功能 - pcnt_set_pin
原型：esp_err_t pcnt_set_pin(pcnt_unit_t unit,
pcnt_channel_t channel, int pulse_io, int ctrl_io)
參數：unit: PCNT unit number
channel: PCNT channel number
pulse_io: Pulse signal input GPIO
ctrl_io: Control signal input GPIO
返回：ESP_OK Success
ESP_ERR_INVALID_ARG Parameter error
說明：Configure PCNT pulse signal input pin and control
input pin.
Note：Set the signal input to PCNT_PIN_NOT_USED
if unused.
範例：
功能 - pcnt_filter_enable
原型：esp_err_t pcnt_filter_enable(pcnt_unit_t unit)
參數：unit: PCNT unit number
返回：ESP_OK Success
ESP_ERR_INVALID_ARG Parameter error
說明：Enable PCNT input filter.
範例：
功能 - pcnt_filter_disable
原型：esp_err_t pcnt_filter_disable(pcnt_unit_t unit)
參數：unit: PCNT unit number
返回：ESP_OK Success
ESP_ERR_INVALID_ARG Parameter error
說明：Disable PCNT input filter.
範例：
功能 - pcnt_set_filter_value
原型：esp_err_t pcnt_set_filter_value(pcnt_unit_t unit,
uint16_t filter_val)
參數：unit: PCNT unit number
filter_val: PCNT signal filter value,
counter in APB_CLK cycles. Any pulses lasting shorter than this will be ignored
when the filter is enabled.
返回：ESP_OK Success
ESP_ERR_INVALID_ARG
Parameter error
說明：Set PCNT filter value.
Note：filter_val is a 10-bit value, so the
maximum filter_val should be limited to 1023.
範例：
功能 - pcnt_get_filter_value
原型：esp_err_t pcnt_get_filter_value(pcnt_unit_t unit,
uint16_t *filter_val)
參數：unit: PCNT unit number
filter_val: Pointer to accept PCNT
filter value.
返回：ESP_OK Success
ESP_ERR_INVALID_ARG Parameter error
說明：Get PCNT filter value.
範例：
功能 - pcnt_set_mode
原型：esp_err_t pcnt_set_mode(pcnt_unit_t unit, pcnt_channel_t
channel, pcnt_count_mode_t pos_mode, pcnt_count_mode_t neg_mode,
pcnt_ctrl_mode_t hctrl_mode, pcnt_ctrl_mode_t lctrl_mode)
參數：unit: PCNT unit number
channel: PCNT channel number
pos_mode: Counter mode when detecting positive
edge
neg_mode: Counter mode when detecting
negative edge
hctrl_mode: Counter mode when control
signal is high level
lctrl_mode: Counter mode when control
signal is low level
返回：ESP_OK Success
ESP_ERR_INVALID_ARG Parameter error
說明：Set PCNT counter mode.
範例：
功能 - pcnt_isr_handler_add
原型：esp_err_t pcnt_isr_handler_add(pcnt_unit_t unit,
void (*isr_handler)(void *), void *args, )
參數：unit: PCNT unit number
isr_handler: Interrupt handler function.
args: Parameter for handler function
返回：ESP_OK Success
ESP_ERR_INVALID_ARG Parameter error
說明：Add ISR handler for specified unit.
Call this function after using pcnt_isr_service_install() to install the
PCNT driver’s ISR handler service.
The ISR handlers do not need to be declared with IRAM_ATTR, unless you
pass the ESP_INTR_FLAG_IRAM flag when allocating the ISR in
pcnt_isr_service_install().
This ISR handler will be called from an ISR. So there is a stack size
limit (configurable as “ISR stack size” in menuconfig). This limit is smaller
compared to a global PCNT interrupt handler due to the additional level of
indirection.
範例：
功能 - pcnt_isr_service_install
原型：esp_err_t pcnt_isr_service_install(int
intr_alloc_flags)
參數：intr_alloc_flags: Flags used to allocate the
interrupt. One or multiple (ORred) ESP_INTR_FLAG_* values. See esp_intr_alloc.h
for more info.
返回：ESP_OK Success
ESP_ERR_NO_MEM No memory to install this
service
ESP_ERR_INVALID_STATE ISR service already
installed
說明：Install PCNT ISR service.
Note：We can manage different interrupt service
for each unit. This function will use the default ISR handle service, Calling
pcnt_isr_service_uninstall to uninstall the default service if needed. Please
do not use pcnt_isr_register if this function was called.
範例：
功能 - pcnt_isr_service_uninstall
原型：void pcnt_isr_service_uninstall(void)
參數：
返回：
說明：Uninstall PCNT ISR service, freeing related
resources.
範例：
功能 - pcnt_isr_handler_remove
原型：esp_err_t pcnt_isr_handler_remove(pcnt_unit_t unit)
參數：unit: PCNT unit number
返回：ESP_OK Success
ESP_ERR_INVALID_ARG Parameter error
說明：Delete ISR handler for specified unit.
範例：相關網址：
※ DIY - ESP32：ESP32 PCNT 脈衝計數器電路（三十八）
※ DIY - ESP32：ESP32 PCNT 脈衝計數器程式（三十九）
※ DIY - ESP32：ESP32 PCNT API 函數模塊介紹（四十）
※ DIY - ESP32：ESP32 PCNT API 函數結構件及其它（四十二）
2018年 11月 29日 天氣報告
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