GPIO & RTC GPIO

[中文]

Overview

The ESP32 chip features 34 physical GPIO pins (GPIO0 ~ GPIO19, GPIO21 ~ GPIO23, GPIO25 ~ GPIO27, and GPIO32 ~ GPIO39). Each pin can be used as a general-purpose I/O, or be connected to an internal peripheral signal. Through IO MUX, RTC IO MUX and the GPIO matrix, peripheral input signals can be from any IO pins, and peripheral output signals can be routed to any IO pins. Together these modules provide highly configurable I/O. For more details, see ESP32 Technical Reference Manual > IO MUX and GPIO Matrix (GPIO, IO_MUX) [PDF].

The table below provides more information on pin usage, and please note the comments in the table for GPIOs with restrictions.

GPIO

Analog Function

RTC GPIO

Comments

GPIO0

ADC2_CH1

RTC_GPIO11

Strapping pin

GPIO1

TXD

GPIO2

ADC2_CH2

RTC_GPIO12

Strapping pin

GPIO3

RXD

GPIO4

ADC2_CH0

RTC_GPIO10

GPIO5

Strapping pin

GPIO6

SPI0/1

GPIO7

SPI0/1

GPIO8

SPI0/1

GPIO9

SPI0/1

GPIO10

SPI0/1

GPIO11

SPI0/1

GPIO12

ADC2_CH5

RTC_GPIO15

Strapping pin; JTAG

GPIO13

ADC2_CH4

RTC_GPIO14

JTAG

GPIO14

ADC2_CH6

RTC_GPIO16

JTAG

GPIO15

ADC2_CH3

RTC_GPIO13

Strapping pin; JTAG

GPIO16

SPI0/1

GPIO17

SPI0/1

GPIO18

GPIO19

GPIO21

GPIO22

GPIO23

GPIO25

ADC2_CH8

RTC_GPIO6

GPIO26

ADC2_CH9

RTC_GPIO7

GPIO27

ADC2_CH7

RTC_GPIO17

GPIO32

ADC1_CH4

RTC_GPIO9

GPIO33

ADC1_CH5

RTC_GPIO8

GPIO34

ADC1_CH6

RTC_GPIO4

GPI

GPIO35

ADC1_CH7

RTC_GPIO5

GPI

GPIO36

ADC1_CH0

RTC_GPIO0

GPI

GPIO37

ADC1_CH1

RTC_GPIO1

GPI

GPIO38

ADC1_CH2

RTC_GPIO2

GPI

GPIO39

ADC1_CH3

RTC_GPIO3

GPI

Note

  • Strapping pin: GPIO0, GPIO2, GPIO5, GPIO12 (MTDI), and GPIO15 (MTDO) are strapping pins. For more infomation, please refer to ESP32 datasheet.

  • SPI0/1: GPIO6-11 and GPIO16-17 are usually connected to the SPI flash and PSRAM integrated on the module and therefore should not be used for other purposes.

  • JTAG: GPIO12-15 are usually used for inline debug.

  • GPI: GPIO34-39 can only be set as input mode and do not have software-enabled pullup or pulldown functions.

  • TXD & RXD are usually used for flashing and debugging.

  • ADC2: ADC2 pins cannot be used when Wi-Fi is used. So, if you are having trouble getting the value from an ADC2 GPIO while using Wi-Fi, you may consider using an ADC1 GPIO instead, which should solve your problem. For more details, please refer to ADC limitations.

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:

Application Example

GPIO output and input interrupt example: peripherals/gpio/generic_gpio.

API Reference - Normal GPIO

Header File

Functions

esp_err_t gpio_config(const gpio_config_t *pGPIOConfig)

GPIO common configuration. 

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

Parameters

pGPIOConfig – Pointer to GPIO configure struct

Returns

  • ESP_OK success

  • ESP_ERR_INVALID_ARG Parameter error

esp_err_t gpio_reset_pin(gpio_num_t gpio_num)

Reset an gpio to default state (select gpio function, enable pullup and disable input and output).

Note

This function also configures the IOMUX for this pin to the GPIO function, and disconnects any other peripheral output configured via GPIO Matrix.

Parameters

gpio_num – GPIO number.

Returns

Always return ESP_OK.

esp_err_t gpio_set_intr_type(gpio_num_t gpio_num, gpio_int_type_t intr_type)

GPIO set interrupt trigger type.

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

Returns

  • ESP_OK Success

  • ESP_ERR_INVALID_ARG Parameter error

esp_err_t gpio_intr_enable(gpio_num_t gpio_num)

Enable GPIO module interrupt signal.

Note

ESP32: Please do not use the interrupt of GPIO36 and GPIO39 when using ADC or Wi-Fi and Bluetooth with sleep mode enabled. Please refer to the comments of adc1_get_raw. Please refer to Section 3.11 of ESP32 ECO and Workarounds for Bugs for the description of this issue. As a workaround, call adc_power_acquire() in the app. This will result in higher power consumption (by ~1mA), but will remove the glitches on GPIO36 and GPIO39.

Parameters

gpio_num – GPIO number. If you want to enable an interrupt on e.g. GPIO16, gpio_num should be GPIO_NUM_16 (16);

Returns

  • ESP_OK Success

  • ESP_ERR_INVALID_ARG Parameter error

esp_err_t gpio_intr_disable(gpio_num_t gpio_num)

Disable GPIO module interrupt signal.

Note

This function is allowed to be executed when Cache is disabled within ISR context, by enabling CONFIG_GPIO_CTRL_FUNC_IN_IRAM

Parameters

gpio_num – GPIO number. If you want to disable the interrupt of e.g. GPIO16, gpio_num should be GPIO_NUM_16 (16);

Returns

  • ESP_OK success

  • ESP_ERR_INVALID_ARG Parameter error

esp_err_t gpio_set_level(gpio_num_t gpio_num, uint32_t level)

GPIO set output level.

Note

This function is allowed to be executed when Cache is disabled within ISR context, by enabling CONFIG_GPIO_CTRL_FUNC_IN_IRAM

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

Returns

  • ESP_OK Success

  • ESP_ERR_INVALID_ARG GPIO number error

int gpio_get_level(gpio_num_t gpio_num)

GPIO get input level.

Warning

If the pad is not configured for input (or input and output) the returned value is always 0.

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);

Returns

  • 0 the GPIO input level is 0

  • 1 the GPIO input level is 1

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

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

Returns

  • ESP_OK Success

  • ESP_ERR_INVALID_ARG GPIO error

esp_err_t gpio_set_pull_mode(gpio_num_t gpio_num, gpio_pull_mode_t pull)

Configure GPIO pull-up/pull-down resistors.

Note

ESP32: Only pins that support both input & output have integrated pull-up and pull-down resistors. Input-only GPIOs 34-39 do not.

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.

Returns

  • ESP_OK Success

  • ESP_ERR_INVALID_ARG : Parameter error

esp_err_t gpio_wakeup_enable(gpio_num_t gpio_num, gpio_int_type_t intr_type)

Enable GPIO wake-up function.

Parameters

  • gpio_num – GPIO number.

  • intr_type – GPIO wake-up type. Only GPIO_INTR_LOW_LEVEL or GPIO_INTR_HIGH_LEVEL can be used.

Returns

  • ESP_OK Success

  • ESP_ERR_INVALID_ARG Parameter error

esp_err_t gpio_wakeup_disable(gpio_num_t gpio_num)

Disable GPIO wake-up function.

Parameters

gpio_num – GPIO number

Returns

  • ESP_OK Success

  • ESP_ERR_INVALID_ARG Parameter error

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.

  • 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.

Returns

  • ESP_OK Success ;

  • ESP_ERR_INVALID_ARG GPIO error

  • ESP_ERR_NOT_FOUND No free interrupt found with the specified flags

esp_err_t gpio_pullup_en(gpio_num_t gpio_num)

Enable pull-up on GPIO.

Parameters

gpio_num – GPIO number

Returns

  • ESP_OK Success

  • ESP_ERR_INVALID_ARG Parameter error

esp_err_t gpio_pullup_dis(gpio_num_t gpio_num)

Disable pull-up on GPIO.

Parameters

gpio_num – GPIO number

Returns

  • ESP_OK Success

  • ESP_ERR_INVALID_ARG Parameter error

esp_err_t gpio_pulldown_en(gpio_num_t gpio_num)

Enable pull-down on GPIO.

Parameters

gpio_num – GPIO number

Returns

  • ESP_OK Success

  • ESP_ERR_INVALID_ARG Parameter error

esp_err_t gpio_pulldown_dis(gpio_num_t gpio_num)

Disable pull-down on GPIO.

Parameters

gpio_num – GPIO number

Returns

  • ESP_OK Success

  • ESP_ERR_INVALID_ARG Parameter error

esp_err_t gpio_install_isr_service(int intr_alloc_flags)

Install the GPIO driver’s ETS_GPIO_INTR_SOURCE 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_handler_add() function.

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.

Returns

  • ESP_OK Success

  • ESP_ERR_NO_MEM No memory to install this service

  • ESP_ERR_INVALID_STATE ISR service already installed.

  • ESP_ERR_NOT_FOUND No free interrupt found with the specified flags

  • ESP_ERR_INVALID_ARG GPIO error

void gpio_uninstall_isr_service(void)

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.

Parameters

  • gpio_num – GPIO number

  • isr_handler – ISR handler function for the corresponding GPIO number.

  • args – parameter for ISR handler.

Returns

  • ESP_OK Success

  • ESP_ERR_INVALID_STATE Wrong state, the ISR service has not been initialized.

  • ESP_ERR_INVALID_ARG Parameter error

esp_err_t gpio_isr_handler_remove(gpio_num_t gpio_num)

Remove ISR handler for the corresponding GPIO pin.

Parameters

gpio_num – GPIO number

Returns

  • ESP_OK Success

  • ESP_ERR_INVALID_STATE Wrong state, the ISR service has not been initialized.

  • ESP_ERR_INVALID_ARG Parameter error

esp_err_t gpio_set_drive_capability(gpio_num_t gpio_num, gpio_drive_cap_t strength)

Set GPIO pad drive capability.

Parameters

  • gpio_num – GPIO number, only support output GPIOs

  • strength – Drive capability of the pad

Returns

  • ESP_OK Success

  • ESP_ERR_INVALID_ARG Parameter error

esp_err_t gpio_get_drive_capability(gpio_num_t gpio_num, gpio_drive_cap_t *strength)

Get GPIO pad drive capability.

Parameters

  • gpio_num – GPIO number, only support output GPIOs

  • strength – Pointer to accept drive capability of the pad

Returns

  • ESP_OK Success

  • ESP_ERR_INVALID_ARG Parameter error

esp_err_t gpio_hold_en(gpio_num_t gpio_num)

Enable gpio pad hold function.

When the pin is set to hold, the state is latched at that moment and will not change no matter how the internal signals change or how the IO MUX/GPIO configuration is modified (including input enable, output enable, output value, function, and drive strength values). It can be used to retain the pin state through a core reset and system reset triggered by watchdog time-out or Deep-sleep events.

The gpio pad hold function works in both input and output modes, but must be output-capable gpios. If pad hold enabled: in output mode: the output level of the pad will be force locked and can not be changed. in input mode: input read value can still reflect the changes of the input signal.

The state of the digital gpio cannot be held during Deep-sleep, and it will resume to hold at its default pin state when the chip wakes up from Deep-sleep. If the digital gpio also needs to be held during Deep-sleep, gpio_deep_sleep_hold_en should also be called.

Power down or call gpio_hold_dis will disable this function.

Parameters

gpio_num – GPIO number, only support output-capable GPIOs

Returns

  • ESP_OK Success

  • ESP_ERR_NOT_SUPPORTED Not support pad hold function

esp_err_t gpio_hold_dis(gpio_num_t gpio_num)

Disable gpio pad hold function.

When the chip is woken up from Deep-sleep, the gpio will be set to the default mode, so, the gpio will output the default level if this function is called. If you don’t want the level changes, the gpio should be configured to a known state before this function is called. e.g. If you hold gpio18 high during Deep-sleep, after the chip is woken up and gpio_hold_dis is called, gpio18 will output low level(because gpio18 is input mode by default). If you don’t want this behavior, you should configure gpio18 as output mode and set it to hight level before calling gpio_hold_dis.

Parameters

gpio_num – GPIO number, only support output-capable GPIOs

Returns

  • ESP_OK Success

  • ESP_ERR_NOT_SUPPORTED Not support pad hold function

void gpio_deep_sleep_hold_en(void)

Enable all digital gpio pads hold function during Deep-sleep.

Enabling this feature makes all digital gpio pads be at the holding state during Deep-sleep. The state of each pad holds is its active configuration (not pad’s sleep configuration!).

Note that this pad hold feature only works when the chip is in Deep-sleep mode. When the chip is in active mode, the digital gpio state can be changed freely even you have called this function.

After this API is being called, the digital gpio Deep-sleep hold feature will work during every sleep process. You should call gpio_deep_sleep_hold_dis to disable this feature.

void gpio_deep_sleep_hold_dis(void)

Disable all digital gpio pads hold function during Deep-sleep.

void gpio_iomux_in(uint32_t gpio_num, uint32_t signal_idx)

Set pad input to a peripheral signal through the IOMUX.

Parameters

  • gpio_num – GPIO number of the pad.

  • signal_idx – Peripheral signal id to input. One of the *_IN_IDX signals in soc/gpio_sig_map.h.

void gpio_iomux_out(uint8_t gpio_num, int func, bool oen_inv)

Set peripheral output to an GPIO pad through the IOMUX.

Parameters

  • gpio_num – gpio_num GPIO number of the pad.

  • func – The function number of the peripheral pin to output pin. One of the FUNC_X_* of specified pin (X) in soc/io_mux_reg.h.

  • oen_inv – True if the output enable needs to be inverted, otherwise False.

esp_err_t gpio_sleep_sel_en(gpio_num_t gpio_num)

Enable SLP_SEL to change GPIO status automantically in lightsleep.

Parameters

gpio_num – GPIO number of the pad.

Returns

  • ESP_OK Success

esp_err_t gpio_sleep_sel_dis(gpio_num_t gpio_num)

Disable SLP_SEL to change GPIO status automantically in lightsleep.

Parameters

gpio_num – GPIO number of the pad.

Returns

  • ESP_OK Success

esp_err_t gpio_sleep_set_direction(gpio_num_t gpio_num, gpio_mode_t mode)

GPIO set direction at sleep.

Configure GPIO direction,such as output_only,input_only,output_and_input

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

Returns

  • ESP_OK Success

  • ESP_ERR_INVALID_ARG GPIO error

esp_err_t gpio_sleep_set_pull_mode(gpio_num_t gpio_num, gpio_pull_mode_t pull)

Configure GPIO pull-up/pull-down resistors at sleep.

Note

ESP32: Only pins that support both input & output have integrated pull-up and pull-down resistors. Input-only GPIOs 34-39 do not.

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.

Returns

  • ESP_OK Success

  • ESP_ERR_INVALID_ARG : Parameter error

Structures

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

Macros

GPIO_PIN_COUNT
GPIO_IS_VALID_GPIO(gpio_num)

Check whether it is a valid GPIO number.

GPIO_IS_VALID_OUTPUT_GPIO(gpio_num)

Check whether it can be a valid GPIO number of output mode.

GPIO_IS_VALID_DIGITAL_IO_PAD(gpio_num)

Check whether it can be a valid digital I/O pad.

Type Definitions

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

GPIO interrupt handler.

Param arg

User registered data

Header File

Macros

GPIO_PIN_REG_0
GPIO_PIN_REG_1
GPIO_PIN_REG_2
GPIO_PIN_REG_3
GPIO_PIN_REG_4
GPIO_PIN_REG_5
GPIO_PIN_REG_6
GPIO_PIN_REG_7
GPIO_PIN_REG_8
GPIO_PIN_REG_9
GPIO_PIN_REG_10
GPIO_PIN_REG_11
GPIO_PIN_REG_12
GPIO_PIN_REG_13
GPIO_PIN_REG_14
GPIO_PIN_REG_15
GPIO_PIN_REG_16
GPIO_PIN_REG_17
GPIO_PIN_REG_18
GPIO_PIN_REG_19
GPIO_PIN_REG_20
GPIO_PIN_REG_21
GPIO_PIN_REG_22
GPIO_PIN_REG_23
GPIO_PIN_REG_24
GPIO_PIN_REG_25
GPIO_PIN_REG_26
GPIO_PIN_REG_27
GPIO_PIN_REG_28
GPIO_PIN_REG_29
GPIO_PIN_REG_30
GPIO_PIN_REG_31
GPIO_PIN_REG_32
GPIO_PIN_REG_33
GPIO_PIN_REG_34
GPIO_PIN_REG_35
GPIO_PIN_REG_36
GPIO_PIN_REG_37
GPIO_PIN_REG_38
GPIO_PIN_REG_39
GPIO_PIN_REG_40
GPIO_PIN_REG_41
GPIO_PIN_REG_42
GPIO_PIN_REG_43
GPIO_PIN_REG_44
GPIO_PIN_REG_45
GPIO_PIN_REG_46
GPIO_PIN_REG_47
GPIO_PIN_REG_48

Enumerations

enum gpio_port_t

Values:

enumerator GPIO_PORT_0
enumerator GPIO_PORT_MAX
enum gpio_num_t

Values:

enumerator GPIO_NUM_NC

Use to signal not connected to S/W

enumerator GPIO_NUM_0

GPIO0, input and output

enumerator GPIO_NUM_1

GPIO1, input and output

enumerator GPIO_NUM_2

GPIO2, input and output

enumerator GPIO_NUM_3

GPIO3, input and output

enumerator GPIO_NUM_4

GPIO4, input and output

enumerator GPIO_NUM_5

GPIO5, input and output

enumerator GPIO_NUM_6

GPIO6, input and output

enumerator GPIO_NUM_7

GPIO7, input and output

enumerator GPIO_NUM_8

GPIO8, input and output

enumerator GPIO_NUM_9

GPIO9, input and output

enumerator GPIO_NUM_10

GPIO10, input and output

enumerator GPIO_NUM_11

GPIO11, input and output

enumerator GPIO_NUM_12

GPIO12, input and output

enumerator GPIO_NUM_13

GPIO13, input and output

enumerator GPIO_NUM_14

GPIO14, input and output

enumerator GPIO_NUM_15

GPIO15, input and output

enumerator GPIO_NUM_16

GPIO16, input and output

enumerator GPIO_NUM_17

GPIO17, input and output

enumerator GPIO_NUM_18

GPIO18, input and output

enumerator GPIO_NUM_19

GPIO19, input and output

enumerator GPIO_NUM_20

GPIO20, input and output

enumerator GPIO_NUM_21

GPIO21, input and output

enumerator GPIO_NUM_22

GPIO22, input and output

enumerator GPIO_NUM_23

GPIO23, input and output

enumerator GPIO_NUM_25

GPIO25, input and output

enumerator GPIO_NUM_26

GPIO26, input and output

enumerator GPIO_NUM_27

GPIO27, input and output

enumerator GPIO_NUM_28

GPIO28, input and output

enumerator GPIO_NUM_29

GPIO29, input and output

enumerator GPIO_NUM_30

GPIO30, input and output

enumerator GPIO_NUM_31

GPIO31, input and output

enumerator GPIO_NUM_32

GPIO32, input and output

enumerator GPIO_NUM_33

GPIO33, input and output

enumerator GPIO_NUM_34

GPIO34, input mode only

enumerator GPIO_NUM_35

GPIO35, input mode only

enumerator GPIO_NUM_36

GPIO36, input mode only

enumerator GPIO_NUM_37

GPIO37, input mode only

enumerator GPIO_NUM_38

GPIO38, input mode only

enumerator GPIO_NUM_39

GPIO39, input mode only

enumerator GPIO_NUM_MAX
enum gpio_int_type_t

Values:

enumerator GPIO_INTR_DISABLE

Disable GPIO interrupt

enumerator GPIO_INTR_POSEDGE

GPIO interrupt type : rising edge

enumerator GPIO_INTR_NEGEDGE

GPIO interrupt type : falling edge

enumerator GPIO_INTR_ANYEDGE

GPIO interrupt type : both rising and falling edge

enumerator GPIO_INTR_LOW_LEVEL

GPIO interrupt type : input low level trigger

enumerator GPIO_INTR_HIGH_LEVEL

GPIO interrupt type : input high level trigger

enumerator GPIO_INTR_MAX
enum gpio_mode_t

Values:

enumerator GPIO_MODE_DISABLE

GPIO mode : disable input and output

enumerator GPIO_MODE_INPUT

GPIO mode : input only

enumerator GPIO_MODE_OUTPUT

GPIO mode : output only mode

enumerator GPIO_MODE_OUTPUT_OD

GPIO mode : output only with open-drain mode

enumerator GPIO_MODE_INPUT_OUTPUT_OD

GPIO mode : output and input with open-drain mode

enumerator GPIO_MODE_INPUT_OUTPUT

GPIO mode : output and input mode

enum gpio_pullup_t

Values:

enumerator GPIO_PULLUP_DISABLE

Disable GPIO pull-up resistor

enumerator GPIO_PULLUP_ENABLE

Enable GPIO pull-up resistor

enum gpio_pulldown_t

Values:

enumerator GPIO_PULLDOWN_DISABLE

Disable GPIO pull-down resistor

enumerator GPIO_PULLDOWN_ENABLE

Enable GPIO pull-down resistor

enum gpio_pull_mode_t

Values:

enumerator GPIO_PULLUP_ONLY

Pad pull up

enumerator GPIO_PULLDOWN_ONLY

Pad pull down

enumerator GPIO_PULLUP_PULLDOWN

Pad pull up + pull down

enumerator GPIO_FLOATING

Pad floating

enum gpio_drive_cap_t

Values:

enumerator GPIO_DRIVE_CAP_0

Pad drive capability: weak

enumerator GPIO_DRIVE_CAP_1

Pad drive capability: stronger

enumerator GPIO_DRIVE_CAP_2

Pad drive capability: medium

enumerator GPIO_DRIVE_CAP_DEFAULT

Pad drive capability: medium

enumerator GPIO_DRIVE_CAP_3

Pad drive capability: strongest

enumerator GPIO_DRIVE_CAP_MAX

API Reference - RTC GPIO

Header File

Functions

bool rtc_gpio_is_valid_gpio(gpio_num_t gpio_num)

Determine if the specified GPIO is a valid RTC GPIO.

Parameters

gpio_num – GPIO number

Returns

true if GPIO is valid for RTC GPIO use. false otherwise.

int rtc_io_number_get(gpio_num_t gpio_num)

Get RTC IO index number by gpio number.

Parameters

gpio_num – GPIO number

Returns

>=0: Index of rtcio. -1 : The gpio is not rtcio.

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.

Parameters

gpio_num – GPIO number (e.g. GPIO_NUM_12)

Returns

  • ESP_OK success

  • ESP_ERR_INVALID_ARG GPIO is not an RTC IO

esp_err_t rtc_gpio_deinit(gpio_num_t gpio_num)

Init a GPIO as digital GPIO.

Parameters

gpio_num – GPIO number (e.g. GPIO_NUM_12)

Returns

  • ESP_OK success

  • ESP_ERR_INVALID_ARG GPIO is not an RTC IO

uint32_t rtc_gpio_get_level(gpio_num_t gpio_num)

Get the RTC IO input level.

Parameters

gpio_num – GPIO number (e.g. GPIO_NUM_12)

Returns

  • 1 High level

  • 0 Low level

  • ESP_ERR_INVALID_ARG GPIO is not an RTC IO

esp_err_t rtc_gpio_set_level(gpio_num_t gpio_num, uint32_t level)

Set the RTC IO output level.

Parameters

  • gpio_num – GPIO number (e.g. GPIO_NUM_12)

  • level – output level

Returns

  • ESP_OK Success

  • ESP_ERR_INVALID_ARG GPIO is not an RTC IO

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.

Parameters

  • gpio_num – GPIO number (e.g. GPIO_NUM_12)

  • mode – GPIO direction

Returns

  • ESP_OK Success

  • ESP_ERR_INVALID_ARG GPIO is not an RTC IO

esp_err_t rtc_gpio_set_direction_in_sleep(gpio_num_t gpio_num, rtc_gpio_mode_t mode)

RTC GPIO set direction in deep sleep mode or disable sleep status (default). In some application scenarios, IO needs to have another states during deep sleep.

NOTE: ESP32 support INPUT_ONLY mode. ESP32S2 support INPUT_ONLY, OUTPUT_ONLY, INPUT_OUTPUT mode.

Parameters

  • gpio_num – GPIO number (e.g. GPIO_NUM_12)

  • mode – GPIO direction

Returns

  • ESP_OK Success

  • ESP_ERR_INVALID_ARG GPIO is not an RTC IO

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.

Parameters

gpio_num – GPIO number (e.g. GPIO_NUM_12)

Returns

  • ESP_OK Success

  • ESP_ERR_INVALID_ARG GPIO is not an RTC IO

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.

Parameters

gpio_num – GPIO number (e.g. GPIO_NUM_12)

Returns

  • ESP_OK Success

  • ESP_ERR_INVALID_ARG GPIO is not an RTC IO

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.

Parameters

gpio_num – GPIO number (e.g. GPIO_NUM_12)

Returns

  • ESP_OK Success

  • ESP_ERR_INVALID_ARG GPIO is not an RTC IO

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.

Parameters

gpio_num – GPIO number (e.g. GPIO_NUM_12)

Returns

  • ESP_OK Success

  • ESP_ERR_INVALID_ARG GPIO is not an RTC IO

esp_err_t rtc_gpio_set_drive_capability(gpio_num_t gpio_num, gpio_drive_cap_t strength)

Set RTC GPIO pad drive capability.

Parameters

  • gpio_num – GPIO number, only support output GPIOs

  • strength – Drive capability of the pad

Returns

  • ESP_OK Success

  • ESP_ERR_INVALID_ARG Parameter error

esp_err_t rtc_gpio_get_drive_capability(gpio_num_t gpio_num, gpio_drive_cap_t *strength)

Get RTC GPIO pad drive capability.

Parameters

  • gpio_num – GPIO number, only support output GPIOs

  • strength – Pointer to accept drive capability of the pad

Returns

  • ESP_OK Success

  • ESP_ERR_INVALID_ARG Parameter error

esp_err_t rtc_gpio_hold_en(gpio_num_t gpio_num)

Enable hold function on an RTC IO pad.

Enabling HOLD function will cause the pad to latch current values of input enable, output enable, output value, function, drive strength values. This function is useful when going into light or deep sleep mode to prevent the pin configuration from changing.

Parameters

gpio_num – GPIO number (e.g. GPIO_NUM_12)

Returns

  • ESP_OK Success

  • ESP_ERR_INVALID_ARG GPIO is not an RTC IO

esp_err_t rtc_gpio_hold_dis(gpio_num_t gpio_num)

Disable hold function on an RTC IO pad.

Disabling hold function will allow the pad receive the values of input enable, output enable, output value, function, drive strength from RTC_IO peripheral.

Parameters

gpio_num – GPIO number (e.g. GPIO_NUM_12)

Returns

  • ESP_OK Success

  • ESP_ERR_INVALID_ARG GPIO is not an RTC IO

esp_err_t rtc_gpio_isolate(gpio_num_t gpio_num)

Helper function to disconnect internal circuits from an RTC IO This function disables input, output, pullup, pulldown, and enables hold feature for an RTC IO. Use this function if an RTC IO needs to be disconnected from internal circuits in deep sleep, to minimize leakage current.

In particular, for ESP32-WROVER module, call rtc_gpio_isolate(GPIO_NUM_12) before entering deep sleep, to reduce deep sleep current.

Parameters

gpio_num – GPIO number (e.g. GPIO_NUM_12).

Returns

  • ESP_OK on success

  • ESP_ERR_INVALID_ARG if GPIO is not an RTC IO

esp_err_t rtc_gpio_force_hold_en_all(void)

Enable force hold signal for all RTC IOs.

Each RTC pad has a “force hold” input signal from the RTC controller. If this signal is set, pad latches current values of input enable, function, output enable, and other signals which come from the RTC mux. Force hold signal is enabled before going into deep sleep for pins which are used for EXT1 wakeup.

esp_err_t rtc_gpio_force_hold_dis_all(void)

Disable force hold signal for all RTC IOs.

esp_err_t rtc_gpio_wakeup_enable(gpio_num_t gpio_num, gpio_int_type_t intr_type)

Enable wakeup from sleep mode using specific GPIO.

Parameters

  • gpio_num – GPIO number

  • intr_type – Wakeup on high level (GPIO_INTR_HIGH_LEVEL) or low level (GPIO_INTR_LOW_LEVEL)

Returns

  • ESP_OK on success

  • ESP_ERR_INVALID_ARG if gpio_num is not an RTC IO, or intr_type is not one of GPIO_INTR_HIGH_LEVEL, GPIO_INTR_LOW_LEVEL.

esp_err_t rtc_gpio_wakeup_disable(gpio_num_t gpio_num)

Disable wakeup from sleep mode using specific GPIO.

Parameters

gpio_num – GPIO number

Returns

  • ESP_OK on success

  • ESP_ERR_INVALID_ARG if gpio_num is not an RTC IO

Macros

RTC_GPIO_IS_VALID_GPIO(gpio_num)

Header File

Enumerations

enum rtc_gpio_mode_t

RTCIO output/input mode type.

Values:

enumerator RTC_GPIO_MODE_INPUT_ONLY

Pad input

enumerator RTC_GPIO_MODE_OUTPUT_ONLY

Pad output

enumerator RTC_GPIO_MODE_INPUT_OUTPUT

Pad input + output

enumerator RTC_GPIO_MODE_DISABLED

Pad (output + input) disable

enumerator RTC_GPIO_MODE_OUTPUT_OD

Pad open-drain output

enumerator RTC_GPIO_MODE_INPUT_OUTPUT_OD

Pad input + open-drain output

Provide feedback about this document