Strapping Pins; Chip Boot Mode Control; Description Of Timing Parameters For The Strapping Pins - Espressif Systems ESP32-H2 Series Hardware Design Manuallines

2 Schematic Checklist
Other UART interfaces can be used as serial ports for communication, which could be mapped to any available
GPIO by software configurations. For these interfaces, it is also recommended to add a series resistor to the TX
line to suppress harmonics.
When using the AT firmware, please note that the UART GPIO is already configured (refer to
Download). It is recommended to use the default configuration.

2.7 Strapping Pins

At each startup or reset, a chip requires some initial configuration parameters, such as in which boot mode to
load the chip, etc. These parameters are passed over via the strapping pins. After reset, the strapping pins work
as normal function pins.
All the information about strapping pins is covered in
In this document we will mainly cover the strapping pins related to boot mode.
GPIO8 and GPIO9 control the boot mode after the reset is released. See Table
Regarding the timing requirements for the strapping pins, there are such parameters as setup time and hold time.
For more information, see Table
Table 3: Description of Timing Parameters for the Strapping Pins
Parameter Description
t Setup time before CHIP_EN goes from low to high
0
t Hold time after CHIP_EN goes high
1
Espressif Systems
ESP32-H2 Series Datasheet
Table 2: Chip Boot Mode Control
Boot Mode
Default Configuration — (Floating)
SPI Boot (default)
Download Boot
1
Invalid combination
1
This combination triggers unexpected behavior
and should be avoided.
3 and Figure 9.
13
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2 Chip Boot Mode
GPIO0 GPIO46
1 (Pull-up)
Any value 1
1 0
0 0
ESP32-H2 Series Hardware Design Guidelines v0.5
AT Firmware
Strapping Pins.
Control.
Min (ms)
0
3