ESP32-H2 family
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Specific properties of ESP32-H2 variant (family)

Specific properties of ESP32-H2 variant (family)

Author
Gunar Schorcht gunar.nosp@m.@sch.nosp@m.orcht.nosp@m..net

Specific properties of ESP32-H2 variant (family)

GPIO pins

ESP32-H2 has 19 broken-out GPIO pins, where a subset can be used as ADC channel and as low-power digital inputs/outputs in deep-sleep mode, the so-called LP GPIOs. Some of them are used by special SoC components. The following table gives a short overview.

Pin Type ADC / LP PU / PD Special function Remarks
GPIO0 In/Out - yes FSPIQ
GPIO1 In/Out ADC yes FSPICS0
GPIO2 In/Out ADC yes MTMS FSPIWP, Bootstrapping
GPIO3 In/Out ADC yes MTDO FSPIHD, Bootstrapping
GPIO4 In/Out ADC yes MTCK FSPICLK
GPIO5 In/Out ADC yes MTDI FSPID
GPIO8 In/Out LP yes Bootstrapping
GPIO9 In/Out LP yes Bootstrapping, pulled up
GPIO10 In/Out LP yes -
GPIO11 In/Out LP yes -
GPIO12 In/Out LP yes -
GPIO13 In/Out LP yes XTAL_32K_P -
GPIO14 In/Out LP yes XTAL_32K_N -
GPIO22 In/Out LP yes -
GPIO23 In/Out - yes UART0 RX -
GPIO24 In/Out - yes UART0 TX -
GPIO25 In/Out - yes Bootstrapping
GPIO26 In/Out - yes USB D- USB Serial / JTAG interface
GPIO27 In/Out - yes USB D+ USB Serial / JTAG interface


ADC: these pins can be used as ADC inputs
LP: these pins are LP GPIOs and can be used in deep-sleep mode
PU/PD: these pins have software configurable pull-up/pull-down functionality.

GPIO2, GPIO3, GPIO8 and GPIO9 are bootstrapping pins which are used to boot ESP32-H2 in different modes:

GPIO9 GPIO8 GPIO2 GPIO3 Mode
1 X x x SPI Boot mode to boot the firmware from flash (default mode)
0 1 x x Joint Download Boot mode for flashing the firmware (standard)
0 0 1 0 SPI Download Boot mode
Other combinations are invalid.


ADC Channels

ESP32-H2 integrates one 12-bit ADC with 5 channels in total: GPIO1, GPIO2, GPIO3, GPIO4 and GPIO5

The maximum number of ADC channels ADC_NUMOF_MAX is 5.

I2C Interfaces

ESP32-H2 has two built-in I2C interfaces.

The following table shows the default configuration of I2C interfaces used for ESP32-H2 boards. It can be overridden by application-specific configurations.

Device Signal Pin Symbol Remarks
I2C_DEV(0) I2C0_SPEED default is I2C_SPEED_FAST
I2C_DEV(0) SCL GPIO10 I2C0_SCL -
I2C_DEV(0) SDA GPIO11 I2C0_SDA -


PWM Channels

The ESP32-H2 LEDC module has 1 channel groups with 6 channels. Each of these channels can be clocked by one of the 4 timers.

SPI Interfaces

ESP32-H2 has three SPI controllers where SPI0 and SPI1 share the same bus. They are used as interface for external memory and can only operate in memory mode:

Thus, only SPI2 (FSPI) can be used as general purpose SPI in RIOT as SPI_DEV(0).

The following table shows the pin configuration used for most boards, even though it can vary from board to board.

Device Signal Pin Symbol Remarks
SPI_DEV(0) SCK GPIO4 SPI0_SCK SPI2_HOST (FSPI)
SPI_DEV(0) MOSI GPIO0 SPI0_MOSI SPI2_HOST (FSPI)
SPI_DEV(0) MISO GPIO5 SPI0_MISO SPI2_HOST (FSPI)
SPI_DEV(0) CS0 GPIO1 SPI0_CS0 SPI2_HOST (FSPI)


Timers

ESP32-H2 has two timer groups with one timer each, resulting in a total of two timers. Thus one timer with one channel can be used in RIOT as timer device TIMER_DEV(0), because one timer is used as system timer.

ESP32-H2 do not have CCOMPARE registers. The counter implementation can not be used.

UART Interfaces

ESP32-H2 integrates two UART interfaces. The following default pin configuration of UART interfaces as used by a most boards can be overridden by the application, see section Application-Specific Configurations.

Device Signal Pin Symbol Remarks
UART_DEV(0) TxD GPIO24 UART0_TXD cannot be changed
UART_DEV(0) RxD GPIO23 UART0_RXD cannot be changed
UART_DEV(1) TxD UART1_TXD optional, can be configured
UART_DEV(1) RxD UART1_RXD optional, can be configured


JTAG Interface

There are two options on how to use the JTAG interface on ESP32-H2:

  1. Using the built-in USB-to-JTAG bridge connected to an USB cable as follows:
    USB Signal ESP32-H2 Pin
    D- (white) GPIO26
    D+ (green) GPIO27
    V_Bus (red) 5V
    Ground (black) GND
  2. Using an external JTAG adapter connected to the JTAG interface exposed to GPIOs as follows:
    JTAG Signal ESP32-H2 Pin
    TRST_N CHIP_PU
    TDO GPIO3 (MTDO)
    TDI GPIO5 (MTDI)
    TCK GPIO4 (MTCK)
    TMS GPIO2 (MTMS)
    GND GND

    Note
    This option requires that the USB D- and USB D+ signals are connected to the ESP32-H2 USB interface at GPIO18 and GPIO19.

    Using the built-in USB-to-JTAG bridge is the default option, i.e. the JTAG interface of the ESP32-H2 is connected to the built-in USB-to-JTAG bridge. To use an external JTAG adapter, the JTAG interface of the ESP32-H2 has to be connected to the GPIOs as shown above. For this purpose eFuses have to be burned with the following command:
    espefuse.py burn_efuse JTAG_SEL_ENABLE --port /dev/ttyUSB0

Once the eFuses are burned with this command and option JTAG_SEL_ENABLE, GPIO25 is used as a bootstrapping pin to choose between the two options. If GPIO25 is HIGH when ESP32-H2 is reset, the JTAG interface is connected to the built-in USB to JTAG bridge and the USB cable can be used for on-chip debugging. Otherwise, the JTAG interface is exposed to GPIO2 ... GPIO5 and an external JTAG adapter has to be used.

Alternatively, the integrated USB-to-JTAG bridge can be permanently disabled with the following command:

espefuse.py burn_efuse DIS_USB_JTAG --port /dev/ttyUSB0

Once the eFuses are burned with this command and option DIS_USB_JTAG, the JTAG interface is always exposed to GPIO2 ... GPIO5 and an external JTAG adapter has to be used.

Note
Burning eFuses is an irreversible operation.

For more information about JTAG configuration for ESP32-H2, refer to the section Configure Other JTAG Interface in the ESP-IDF documentation.