GPIO & RTC GPIO

Overview

The ESP32 chip features 40 physical GPIO pads. Some GPIO pads cannot be used or do not have the corresponding pin on the chip package(refer to technical reference manual ). Each pad can be used as a general purpose I/O or can be connected to an internal peripheral signal.

  • Note that GPIO6-11 are usually used for SPI flash.
  • GPIO34-39 can only be set as input mode and do not have software pullup or pulldown functions.

There is also separate “RTC GPIO” support, which functions when GPIOs are routed to the “RTC” low-power and analog subsystem. These pin functions can be used when in deep sleep, when the Ultra Low Power co-processor is running, or when analog functions such as ADC/DAC/etc are in use.

Application Example

GPIO output and input interrupt example: peripherals/gpio.

API Reference

Macros

Normal GPIO

GPIO_SEL_0 (BIT(0))

Pin 0 selected

GPIO_SEL_1 (BIT(1))

Pin 1 selected

GPIO_SEL_2 (BIT(2))

Pin 2 selected

GPIO_SEL_3 (BIT(3))

Pin 3 selected

GPIO_SEL_4 (BIT(4))

Pin 4 selected

GPIO_SEL_5 (BIT(5))

Pin 5 selected

GPIO_SEL_6 (BIT(6))

Pin 6 selected

GPIO_SEL_7 (BIT(7))

Pin 7 selected

GPIO_SEL_8 (BIT(8))

Pin 8 selected

GPIO_SEL_9 (BIT(9))

Pin 9 selected

GPIO_SEL_10 (BIT(10))

Pin 10 selected

GPIO_SEL_11 (BIT(11))

Pin 11 selected

GPIO_SEL_12 (BIT(12))

Pin 12 selected

GPIO_SEL_13 (BIT(13))

Pin 13 selected

GPIO_SEL_14 (BIT(14))

Pin 14 selected

GPIO_SEL_15 (BIT(15))

Pin 15 selected

GPIO_SEL_16 (BIT(16))

Pin 16 selected

GPIO_SEL_17 (BIT(17))

Pin 17 selected

GPIO_SEL_18 (BIT(18))

Pin 18 selected

GPIO_SEL_19 (BIT(19))

Pin 19 selected

GPIO_SEL_21 (BIT(21))

Pin 21 selected

GPIO_SEL_22 (BIT(22))

Pin 22 selected

GPIO_SEL_23 (BIT(23))

Pin 23 selected

GPIO_SEL_25 (BIT(25))

Pin 25 selected

GPIO_SEL_26 (BIT(26))

Pin 26 selected

GPIO_SEL_27 (BIT(27))

Pin 27 selected

GPIO_SEL_32 ((uint64_t)(((uint64_t)1)<<32))

Pin 32 selected

GPIO_SEL_33 ((uint64_t)(((uint64_t)1)<<33))

Pin 33 selected

GPIO_SEL_34 ((uint64_t)(((uint64_t)1)<<34))

Pin 34 selected

GPIO_SEL_35 ((uint64_t)(((uint64_t)1)<<35))

Pin 35 selected

GPIO_SEL_36 ((uint64_t)(((uint64_t)1)<<36))

Pin 36 selected

GPIO_SEL_37 ((uint64_t)(((uint64_t)1)<<37))

Pin 37 selected

GPIO_SEL_38 ((uint64_t)(((uint64_t)1)<<38))

Pin 38 selected

GPIO_SEL_39 ((uint64_t)(((uint64_t)1)<<39))

Pin 39 selected

GPIO_PIN_REG_0 PERIPHS_IO_MUX_GPIO0_U
GPIO_PIN_REG_1 PERIPHS_IO_MUX_U0TXD_U
GPIO_PIN_REG_2 PERIPHS_IO_MUX_GPIO2_U
GPIO_PIN_REG_3 PERIPHS_IO_MUX_U0RXD_U
GPIO_PIN_REG_4 PERIPHS_IO_MUX_GPIO4_U
GPIO_PIN_REG_5 PERIPHS_IO_MUX_GPIO5_U
GPIO_PIN_REG_6 PERIPHS_IO_MUX_SD_CLK_U
GPIO_PIN_REG_7 PERIPHS_IO_MUX_SD_DATA0_U
GPIO_PIN_REG_8 PERIPHS_IO_MUX_SD_DATA1_U
GPIO_PIN_REG_9 PERIPHS_IO_MUX_SD_DATA2_U
GPIO_PIN_REG_10 PERIPHS_IO_MUX_SD_DATA3_U
GPIO_PIN_REG_11 PERIPHS_IO_MUX_SD_CMD_U
GPIO_PIN_REG_12 PERIPHS_IO_MUX_MTDI_U
GPIO_PIN_REG_13 PERIPHS_IO_MUX_MTCK_U
GPIO_PIN_REG_14 PERIPHS_IO_MUX_MTMS_U
GPIO_PIN_REG_15 PERIPHS_IO_MUX_MTDO_U
GPIO_PIN_REG_16 PERIPHS_IO_MUX_GPIO16_U
GPIO_PIN_REG_17 PERIPHS_IO_MUX_GPIO17_U
GPIO_PIN_REG_18 PERIPHS_IO_MUX_GPIO18_U
GPIO_PIN_REG_19 PERIPHS_IO_MUX_GPIO19_U
GPIO_PIN_REG_20 PERIPHS_IO_MUX_GPIO20_U
GPIO_PIN_REG_21 PERIPHS_IO_MUX_GPIO21_U
GPIO_PIN_REG_22 PERIPHS_IO_MUX_GPIO22_U
GPIO_PIN_REG_23 PERIPHS_IO_MUX_GPIO23_U
GPIO_PIN_REG_25 PERIPHS_IO_MUX_GPIO25_U
GPIO_PIN_REG_26 PERIPHS_IO_MUX_GPIO26_U
GPIO_PIN_REG_27 PERIPHS_IO_MUX_GPIO27_U
GPIO_PIN_REG_32 PERIPHS_IO_MUX_GPIO32_U
GPIO_PIN_REG_33 PERIPHS_IO_MUX_GPIO33_U
GPIO_PIN_REG_34 PERIPHS_IO_MUX_GPIO34_U
GPIO_PIN_REG_35 PERIPHS_IO_MUX_GPIO35_U
GPIO_PIN_REG_36 PERIPHS_IO_MUX_GPIO36_U
GPIO_PIN_REG_37 PERIPHS_IO_MUX_GPIO37_U
GPIO_PIN_REG_38 PERIPHS_IO_MUX_GPIO38_U
GPIO_PIN_REG_39 PERIPHS_IO_MUX_GPIO39_U
GPIO_APP_CPU_INTR_ENA (BIT(0))
GPIO_APP_CPU_NMI_INTR_ENA (BIT(1))
GPIO_PRO_CPU_INTR_ENA (BIT(2))
GPIO_PRO_CPU_NMI_INTR_ENA (BIT(3))
GPIO_SDIO_EXT_INTR_ENA (BIT(4))
GPIO_MODE_DEF_INPUT (BIT0)
GPIO_MODE_DEF_OUTPUT (BIT1)
GPIO_MODE_DEF_OD (BIT2)
GPIO_PIN_COUNT 40
GPIO_IS_VALID_GPIO(gpio_num) ((gpio_num < GPIO_PIN_COUNT && GPIO_PIN_MUX_REG[gpio_num] != 0))
GPIO_IS_VALID_OUTPUT_GPIO(gpio_num) ((GPIO_IS_VALID_GPIO(gpio_num)) && (gpio_num < 34))

Type Definitions

Normal GPIO

typedef void (*gpio_isr_t)(void *)
typedef intr_handle_t gpio_isr_handle_t

Enumerations

Normal GPIO

enum gpio_num_t

Values:

GPIO_NUM_0 = 0

GPIO0, input and output

GPIO_NUM_1 = 1

GPIO1, input and output

GPIO_NUM_2 = 2

GPIO2, input and output

GPIO_NUM_3 = 3

GPIO3, input and output

GPIO_NUM_4 = 4

GPIO4, input and output

GPIO_NUM_5 = 5

GPIO5, input and output

GPIO_NUM_6 = 6

GPIO6, input and output

GPIO_NUM_7 = 7

GPIO7, input and output

GPIO_NUM_8 = 8

GPIO8, input and output

GPIO_NUM_9 = 9

GPIO9, input and output

GPIO_NUM_10 = 10

GPIO10, input and output

GPIO_NUM_11 = 11

GPIO11, input and output

GPIO_NUM_12 = 12

GPIO12, input and output

GPIO_NUM_13 = 13

GPIO13, input and output

GPIO_NUM_14 = 14

GPIO14, input and output

GPIO_NUM_15 = 15

GPIO15, input and output

GPIO_NUM_16 = 16

GPIO16, input and output

GPIO_NUM_17 = 17

GPIO17, input and output

GPIO_NUM_18 = 18

GPIO18, input and output

GPIO_NUM_19 = 19

GPIO19, input and output

GPIO_NUM_21 = 21

GPIO21, input and output

GPIO_NUM_22 = 22

GPIO22, input and output

GPIO_NUM_23 = 23

GPIO23, input and output

GPIO_NUM_25 = 25

GPIO25, input and output

GPIO_NUM_26 = 26

GPIO26, input and output

GPIO_NUM_27 = 27

GPIO27, input and output

GPIO_NUM_32 = 32

GPIO32, input and output

GPIO_NUM_33 = 33

GPIO32, input and output

GPIO_NUM_34 = 34

GPIO34, input mode only

GPIO_NUM_35 = 35

GPIO35, input mode only

GPIO_NUM_36 = 36

GPIO36, input mode only

GPIO_NUM_37 = 37

GPIO37, input mode only

GPIO_NUM_38 = 38

GPIO38, input mode only

GPIO_NUM_39 = 39

GPIO39, input mode only

GPIO_NUM_MAX = 40
enum gpio_int_type_t

Values:

GPIO_INTR_DISABLE = 0

Disable GPIO interrupt

GPIO_INTR_POSEDGE = 1

GPIO interrupt type : rising edge

GPIO_INTR_NEGEDGE = 2

GPIO interrupt type : falling edge

GPIO_INTR_ANYEDGE = 3

GPIO interrupt type : both rising and falling edge

GPIO_INTR_LOW_LEVEL = 4

GPIO interrupt type : input low level trigger

GPIO_INTR_HIGH_LEVEL = 5

GPIO interrupt type : input high level trigger

GPIO_INTR_MAX
enum gpio_mode_t

Values:

GPIO_MODE_INPUT = GPIO_MODE_DEF_INPUT

GPIO mode : input only

GPIO_MODE_OUTPUT = GPIO_MODE_DEF_OUTPUT

GPIO mode : output only mode

GPIO_MODE_OUTPUT_OD = ((GPIO_MODE_DEF_OUTPUT)|(GPIO_MODE_DEF_OD))

GPIO mode : output only with open-drain mode

GPIO_MODE_INPUT_OUTPUT_OD = ((GPIO_MODE_DEF_INPUT)|(GPIO_MODE_DEF_OUTPUT)|(GPIO_MODE_DEF_OD))

GPIO mode : output and input with open-drain mode

GPIO_MODE_INPUT_OUTPUT = ((GPIO_MODE_DEF_INPUT)|(GPIO_MODE_DEF_OUTPUT))

GPIO mode : output and input mode

enum gpio_pullup_t

Values:

GPIO_PULLUP_DISABLE = 0x0

Disable GPIO pull-up resistor

GPIO_PULLUP_ENABLE = 0x1

Enable GPIO pull-up resistor

enum gpio_pulldown_t

Values:

GPIO_PULLDOWN_DISABLE = 0x0

Disable GPIO pull-down resistor

GPIO_PULLDOWN_ENABLE = 0x1

Enable GPIO pull-down resistor

enum gpio_pull_mode_t

Values:

GPIO_PULLUP_ONLY

Pad pull up

GPIO_PULLDOWN_ONLY

Pad pull down

GPIO_PULLUP_PULLDOWN

Pad pull up + pull down

GPIO_FLOATING

Pad floating

RTC GPIO

enum rtc_gpio_mode_t

Values:

RTC_GPIO_MODE_INPUT_ONLY

Pad output

RTC_GPIO_MODE_OUTPUT_ONLY

Pad input

RTC_GPIO_MODE_INPUT_OUTUT

Pad pull output + input

RTC_GPIO_MODE_DISABLED

Pad (output + input) disable

Structures

Normal GPIO

struct gpio_config_t

Configuration parameters of GPIO pad for gpio_config function.

Public Members

uint64_t pin_bit_mask

GPIO pin: set with bit mask, each bit maps to a GPIO

gpio_mode_t mode

GPIO mode: set input/output mode

gpio_pullup_t pull_up_en

GPIO pull-up

gpio_pulldown_t pull_down_en

GPIO pull-down

gpio_int_type_t intr_type

GPIO interrupt type

Functions

Normal GPIO

esp_err_t gpio_config(gpio_config_t *pGPIOConfig)

GPIO common configuration.

Configure GPIO’s Mode,pull-up,PullDown,IntrType

Return
  • ESP_OK success
  • ESP_ERR_INVALID_ARG Parameter error
Parameters
  • pGPIOConfig: Pointer to GPIO configure struct

esp_err_t gpio_set_intr_type(gpio_num_t gpio_num, gpio_int_type_t intr_type)

GPIO set interrupt trigger type.

Return
  • ESP_OK Success
  • ESP_ERR_INVALID_ARG Parameter error
Parameters
  • gpio_num: GPIO number. If you want to set the trigger type of e.g. of GPIO16, gpio_num should be GPIO_NUM_16 (16);
  • intr_type: Interrupt type, select from gpio_int_type_t

esp_err_t gpio_intr_enable(gpio_num_t gpio_num)

Enable GPIO module interrupt signal.

Return
  • ESP_OK Success
  • ESP_ERR_INVALID_ARG Parameter error
Parameters
  • gpio_num: GPIO number. If you want to enable an interrupt on e.g. GPIO16, gpio_num should be GPIO_NUM_16 (16);

esp_err_t gpio_intr_disable(gpio_num_t gpio_num)

Disable GPIO module interrupt signal.

Return
  • ESP_OK success
  • ESP_ERR_INVALID_ARG Parameter error
Parameters
  • gpio_num: GPIO number. If you want to disable the interrupt of e.g. GPIO16, gpio_num should be GPIO_NUM_16 (16);

esp_err_t gpio_set_level(gpio_num_t gpio_num, uint32_t level)

GPIO set output level.

Return
  • ESP_OK Success
  • ESP_ERR_INVALID_ARG GPIO number error
Parameters
  • gpio_num: GPIO number. If you want to set the output level of e.g. GPIO16, gpio_num should be GPIO_NUM_16 (16);
  • level: Output level. 0: low ; 1: high

int gpio_get_level(gpio_num_t gpio_num)

GPIO get input level.

Return
  • 0 the GPIO input level is 0
  • 1 the GPIO input level is 1
Parameters
  • gpio_num: GPIO number. If you want to get the logic level of e.g. pin GPIO16, gpio_num should be GPIO_NUM_16 (16);

esp_err_t gpio_set_direction(gpio_num_t gpio_num, gpio_mode_t mode)

GPIO set direction.

Configure GPIO direction,such as output_only,input_only,output_and_input

Return
  • ESP_OK Success
  • ESP_ERR_INVALID_ARG GPIO error
Parameters
  • gpio_num: Configure GPIO pins number, it should be GPIO number. If you want to set direction of e.g. GPIO16, gpio_num should be GPIO_NUM_16 (16);
  • mode: GPIO direction

esp_err_t gpio_set_pull_mode(gpio_num_t gpio_num, gpio_pull_mode_t pull)

Configure GPIO pull-up/pull-down resistors.

Only pins that support both input & output have integrated pull-up and pull-down resistors. Input-only GPIOs 34-39 do not.

Return
  • ESP_OK Success
  • ESP_ERR_INVALID_ARG : Parameter error
Parameters
  • gpio_num: GPIO number. If you want to set pull up or down mode for e.g. GPIO16, gpio_num should be GPIO_NUM_16 (16);
  • pull: GPIO pull up/down mode.

esp_err_t gpio_wakeup_enable(gpio_num_t gpio_num, gpio_int_type_t intr_type)

Enable GPIO wake-up function.

Return
  • ESP_OK Success
  • ESP_ERR_INVALID_ARG Parameter error
Parameters
  • gpio_num: GPIO number.
  • intr_type: GPIO wake-up type. Only GPIO_INTR_LOW_LEVEL or GPIO_INTR_HIGH_LEVEL can be used.

esp_err_t gpio_wakeup_disable(gpio_num_t gpio_num)

Disable GPIO wake-up function.

Return
  • ESP_OK Success
  • ESP_ERR_INVALID_ARG Parameter error
Parameters
  • gpio_num: GPIO number

esp_err_t gpio_isr_register(void (*fn)(void *), void *arg, int intr_alloc_flags, gpio_isr_handle_t *handle, )

Register GPIO interrupt handler, the handler is an ISR. The handler will be attached to the same CPU core that this function is running on.

This ISR function is called whenever any GPIO interrupt occurs. See the alternative gpio_install_isr_service() and gpio_isr_handler_add() API in order to have the driver support per-GPIO ISRs.

To disable or remove the ISR, pass the returned handle to the interrupt allocation functions.

Parameters
  • fn: Interrupt 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.
  • arg: Parameter for handler function
  • handle: Pointer to return handle. If non-NULL, a handle for the interrupt will be returned here.

Return
  • ESP_OK Success ;
  • ESP_ERR_INVALID_ARG GPIO error

esp_err_t gpio_pullup_en(gpio_num_t gpio_num)

Enable pull-up on GPIO.

Return
  • ESP_OK Success
  • ESP_ERR_INVALID_ARG Parameter error
Parameters
  • gpio_num: GPIO number

esp_err_t gpio_pullup_dis(gpio_num_t gpio_num)

Disable pull-up on GPIO.

Return
  • ESP_OK Success
  • ESP_ERR_INVALID_ARG Parameter error
Parameters
  • gpio_num: GPIO number

esp_err_t gpio_pulldown_en(gpio_num_t gpio_num)

Enable pull-down on GPIO.

Return
  • ESP_OK Success
  • ESP_ERR_INVALID_ARG Parameter error
Parameters
  • gpio_num: GPIO number

esp_err_t gpio_pulldown_dis(gpio_num_t gpio_num)

Disable pull-down on GPIO.

Return
  • ESP_OK Success
  • ESP_ERR_INVALID_ARG Parameter error
Parameters
  • gpio_num: GPIO number

esp_err_t gpio_install_isr_service(int intr_alloc_flags)

Install the driver’s GPIO ISR handler service, which allows per-pin GPIO interrupt handlers.

This function is incompatible with gpio_isr_register() - if that function is used, a single global ISR is registered for all GPIO interrupts. If this function is used, the ISR service provides a global GPIO ISR and individual pin handlers are registered via the gpio_isr_register() function.

Return
  • ESP_OK Success
  • ESP_FAIL Operation fail
  • ESP_ERR_NO_MEM No memory to install this service
Parameters
  • 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.

void gpio_uninstall_isr_service()

Uninstall the driver’s GPIO ISR service, freeing related resources.

esp_err_t gpio_isr_handler_add(gpio_num_t gpio_num, gpio_isr_t isr_handler, void *args)

Add ISR handler for the corresponding GPIO pin.

Call this function after using gpio_install_isr_service() to install the driver’s GPIO ISR handler service.

The pin ISR handlers no longer need to be declared with IRAM_ATTR, unless you pass the ESP_INTR_FLAG_IRAM flag when allocating the ISR in gpio_install_isr_service().

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 GPIO interrupt handler due to the additional level of indirection.

Return
  • ESP_OK Success
  • ESP_ERR_INVALID_STATE Wrong state, the ISR service has not been initialized.
  • ESP_ERR_INVALID_ARG Parameter error
Parameters
  • gpio_num: GPIO number
  • isr_handler: ISR handler function for the corresponding GPIO number.
  • args: parameter for ISR handler.

esp_err_t gpio_isr_handler_remove(gpio_num_t gpio_num)

Remove ISR handler for the corresponding GPIO pin.

Return
  • ESP_OK Success
  • ESP_ERR_INVALID_STATE Wrong state, the ISR service has not been initialized.
  • ESP_ERR_INVALID_ARG Parameter error
Parameters
  • gpio_num: GPIO number

RTC GPIO

static bool rtc_gpio_is_valid_gpio(gpio_num_t gpio_num)

Determine if the specified GPIO is a valid RTC GPIO.

Return
true if GPIO is valid for RTC GPIO use. talse otherwise.
Parameters
  • gpio_num: GPIO number

esp_err_t rtc_gpio_init(gpio_num_t gpio_num)

Init a GPIO as RTC GPIO.

This function must be called when initializing a pad for an analog function.

Return
  • ESP_OK success
  • ESP_ERR_INVALID_ARG GPIO is not an RTC IO
Parameters
  • gpio_num: GPIO number (e.g. GPIO_NUM_12)

esp_err_t rtc_gpio_deinit(gpio_num_t gpio_num)

Init a GPIO as digital GPIO.

Return
  • ESP_OK success
  • ESP_ERR_INVALID_ARG GPIO is not an RTC IO
Parameters
  • gpio_num: GPIO number (e.g. GPIO_NUM_12)

uint32_t rtc_gpio_get_level(gpio_num_t gpio_num)

Get the RTC IO input level.

Return
  • 1 High level
  • 0 Low level
  • ESP_ERR_INVALID_ARG GPIO is not an RTC IO
Parameters
  • gpio_num: GPIO number (e.g. GPIO_NUM_12)

esp_err_t rtc_gpio_set_level(gpio_num_t gpio_num, uint32_t level)

Set the RTC IO output level.

Return
  • ESP_OK Success
  • ESP_ERR_INVALID_ARG GPIO is not an RTC IO
Parameters
  • gpio_num: GPIO number (e.g. GPIO_NUM_12)
  • level: output level

esp_err_t rtc_gpio_set_direction(gpio_num_t gpio_num, rtc_gpio_mode_t mode)

RTC GPIO set direction.

Configure RTC GPIO direction, such as output only, input only, output and input.

Return
  • ESP_OK Success
  • ESP_ERR_INVALID_ARG GPIO is not an RTC IO
Parameters
  • gpio_num: GPIO number (e.g. GPIO_NUM_12)
  • mode: GPIO direction

esp_err_t rtc_gpio_pullup_en(gpio_num_t gpio_num)

RTC GPIO pullup enable.

This function only works for RTC IOs. In general, call gpio_pullup_en, which will work both for normal GPIOs and RTC IOs.

Return
  • ESP_OK Success
  • ESP_ERR_INVALID_ARG GPIO is not an RTC IO
Parameters
  • gpio_num: GPIO number (e.g. GPIO_NUM_12)

esp_err_t rtc_gpio_pulldown_en(gpio_num_t gpio_num)

RTC GPIO pulldown enable.

This function only works for RTC IOs. In general, call gpio_pulldown_en, which will work both for normal GPIOs and RTC IOs.

Return
  • ESP_OK Success
  • ESP_ERR_INVALID_ARG GPIO is not an RTC IO
Parameters
  • gpio_num: GPIO number (e.g. GPIO_NUM_12)

esp_err_t rtc_gpio_pullup_dis(gpio_num_t gpio_num)

RTC GPIO pullup disable.

This function only works for RTC IOs. In general, call gpio_pullup_dis, which will work both for normal GPIOs and RTC IOs.

Return
  • ESP_OK Success
  • ESP_ERR_INVALID_ARG GPIO is not an RTC IO
Parameters
  • gpio_num: GPIO number (e.g. GPIO_NUM_12)

esp_err_t rtc_gpio_pulldown_dis(gpio_num_t gpio_num)

RTC GPIO pulldown disable.

This function only works for RTC IOs. In general, call gpio_pulldown_dis, which will work both for normal GPIOs and RTC IOs.

Return
  • ESP_OK Success
  • ESP_ERR_INVALID_ARG GPIO is not an RTC IO
Parameters
  • gpio_num: GPIO number (e.g. GPIO_NUM_12)

Warning

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