pcnt
简介
pcnt 外设类型用于描述 ESP-IDF pulse counter 单元、glitch filter、channel 与 watch point。BMGR 根据该配置创建 PCNT unit 与 channel，并返回 periph_pcnt_handle_t。
该外设适用于需要直接使用 PCNT 句柄的计数、编码器或测试场景。计数值读取、事件回调与业务层处理由使用该句柄的设备或应用代码完成。
支持的工作模式
pcnt 当前按单个 PCNT unit 配置，不通过 role 进一步拆分工作模式。
最小配置
PCNT 计数单元
board_peripherals.yaml：
peripherals:
- name: pcnt_unit
type: pcnt
config:
unit_config:
low_limit: -100
high_limit: 100
intr_priority: 0
flags:
accum_count: false
filter_config:
max_glitch_ns: 1000
channel_count: 1
channel_list:
- channel: 0
channel_config:
edge_gpio_num: 7
level_gpio_num: -1
flags:
invert_edge_input: false
invert_level_input: false
virt_edge_io_level: 0
virt_level_io_level: 0
io_loop_back: false
pos_act: PCNT_CHANNEL_EDGE_ACTION_INCREASE
neg_act: PCNT_CHANNEL_EDGE_ACTION_DECREASE
high_act: PCNT_CHANNEL_LEVEL_ACTION_KEEP
low_act: PCNT_CHANNEL_LEVEL_ACTION_KEEP
watch_point_count: 3
watch_point_list: [-100, 0, 100]
模式说明
pcnt 外设先创建 unit，再设置 glitch filter，然后按 channel_count 创建 channel 并设置 edge/level action。watch_point_list 用于向 unit 添加 watch point；事件回调不在外设初始化中注册。
完整字段
PCNT 计数单元完整字段
# PCNT Peripheral Default Configuration
# This file shows the default values used by the PCNT peripheral parser
# Based on periph_pcnt.py parsing script
- name: pcnt_unit
type: pcnt
config:
unit_config:
low_limit: -100 # [TO_BE_CONFIRMED] Low count limit (should be lower than 0 and should not less than 'PCNT_LL_MIN_LIM')
high_limit: 100 # [TO_BE_CONFIRMED] High count limit (should be higher than 0 and should not exceed 'PCNT_LL_MAX_LIM')
intr_priority: 0 # PCNT interrupt priority,
# if set to 0, the driver will try to allocate an interrupt with a relative low priority (1,2,3)
flags:
accum_count: false # Whether to accumulate the count value when overflows at the high/low limit
# The following two flags require chip support,
# which can be determined by checking the macro definition SOC_PCNT_SUPPORT_STEP_NOTIFY
# or by referring to the IDF Programming Guide
en_step_notify_up: false # Enable step notify in the positive direction
en_step_notify_down: false # Enable step notify in the negative direction
filter_config:
max_glitch_ns: 1000 # Pulse width smaller than this threshold will be treated as glitch and ignored, in the unit of ns
channel_count: 2 # [TO_BE_CONFIRMED] Number of PCNT channels to configure, should be less than SOC_PCNT_CHANNELS_PER_UNIT
# Configuration for each PCNT channel
channel_list:
# Channel 0 configuration
- channel: 0
channel_config:
edge_gpio_num: -1 # [IO] GPIO number used by the edge signal, input mode with pull up enabled. Set to -1 if unused
level_gpio_num: -1 # [IO] GPIO number used by the level signal, input mode with pull up enabled. Set to -1 if unused
flags:
invert_edge_input: false # Invert the input edge signal
invert_level_input: false # Invert the input level signal
virt_edge_io_level: 0 # Virtual edge IO level, 0: low, 1: high. Only valid when edge_gpio_num is set to -1
virt_level_io_level: 0 # Virtual level IO level, 0: low, 1: high. Only valid when level_gpio_num is set to -1
io_loop_back: false # For debug/test, the signal output from the GPIO will be fed to the input path as well.
# Note that this flag is deprecated, will be removed in IDF v6.0.
# Instead, you can configure the output mode by calling gpio_config() first, and then do PCNT channel configuration.
# Necessary configurations for the IO to be used as the PCNT input will be appended.
# Edge actions for pcnt channel
pos_act: PCNT_CHANNEL_EDGE_ACTION_DECREASE
neg_act: PCNT_CHANNEL_EDGE_ACTION_INCREASE
# Valid values:
# - PCNT_CHANNEL_EDGE_ACTION_HOLD Hold current count value
# - PCNT_CHANNEL_EDGE_ACTION_INCREASE Increase count value
# - PCNT_CHANNEL_EDGE_ACTION_DECREASE Decrease count value
# Level actions for pcnt channel
high_act: PCNT_CHANNEL_LEVEL_ACTION_KEEP
low_act: PCNT_CHANNEL_LEVEL_ACTION_INVERSE
# Valid values:
# - PCNT_CHANNEL_LEVEL_ACTION_KEEP Keep the current count value
# - PCNT_CHANNEL_LEVEL_ACTION_INVERSE Invert current count mode (increase -> decrease, decrease -> increase)
# - PCNT_CHANNEL_LEVEL_ACTION_HOLD Hold current count value
# Channel 1 configuration
- channel: 1
channel_config:
edge_gpio_num: 38 # [IO] GPIO number used by the edge signal
level_gpio_num: 37 # [IO] GPIO number used by the level signal
flags:
invert_edge_input: false
invert_level_input: false
virt_edge_io_level: false
virt_level_io_level: false
io_loop_back: false
pos_act: PCNT_CHANNEL_EDGE_ACTION_INCREASE
neg_act: PCNT_CHANNEL_EDGE_ACTION_DECREASE
high_act: PCNT_CHANNEL_LEVEL_ACTION_KEEP
low_act: PCNT_CHANNEL_LEVEL_ACTION_INVERSE
# Watch point configuration
watch_point_count: 5 # Number of watch points to configure,
# In addition to setting 0 and +/- limit as watch points,
# users can also customize SOC_PCNT_THRES_POINT_PER_UNIT watch points
watch_point_list: [-100, -50, 0, 50, 100]
适用设备
device type |
使用方式 |
说明 |
|---|---|---|
|
设备侧可引用已定义的 |
计数读取、watch point 回调和业务语义由自定义设备或应用代码完成 |
参考代码
esp_board_manager/peripherals/periph_pcnt/periph_pcnt.cesp_board_manager/test_apps/main/periph/test_periph_pcnt.c
板级参考
esp_board_manager/test_apps/components/board_customer/boards/esp32_s3_devkitc/board_peripherals.yaml：定义pcnt_unit测试外设。
注意事项
channel_count不能超过目标芯片支持的SOC_PCNT_CHANNELS_PER_UNIT；BMGR 初始化时会按上限截断并打印 warning。watch_point_count不能超过目标芯片支持的 watch point 数量加上边界点容量；BMGR 初始化时会按上限截断并打印 warning。edge_gpio_num或level_gpio_num设为-1时，对应 virtual IO level 字段才有意义。修改 PCNT 外设配置后，需要重新执行
idf.py bmgr -b <board>。
调试技巧
API 参考
使用 esp_board_manager_get_periph_handle() 获取 PCNT 外设句柄，句柄类型为 periph_pcnt_handle_t：
typedef struct {
pcnt_unit_handle_t pcnt_unit; /*!< Handle to the PCNT unit */
pcnt_channel_handle_t channels[SOC_PCNT_CHANNELS_PER_UNIT]; /*!< Array of handles for PCNT channels */
} periph_pcnt_handle_t;
pcnt_unit 可传入 pcnt_unit_* 系列 API 进行计数器使能、清零和值读取；channels 数组可按通道索引传入 pcnt_channel_* API 调整边沿和电平响应动作。
相关声明位于 esp_board_manager/peripherals/periph_pcnt/periph_pcnt.h。
底层 ESP-IDF 驱动文档：脉冲计数器 (PCNT)。