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6
IO0, IO45, IO46 are connected to internal pull-up/pull-down by default. If these pins are not
connected externally or the connected external circuit is in a high impedance state, the internal
weak pull-up/pull-down will determine the default value of the input level of these pins.
To change the value of strapping, users can apply external pull-down/pull-up resistors, or use the
GPIO of the host MCU to control the strapping pin level of ESP32-S2 during power-on reset.
After reset, the strapping pins work as normal-function pins.
Refer to Table 2 for a detailed boot-mode configuration of the strapping pins.
Table 2 Strapping Pins
VDD_SPI voltage
1
Pin
Default
3.3 V
1.8 V
IO45
2
drop down
0
1
Booting Mode
1
Pin
Default
SPI Boot
Download Boot
IO0
pull up
1
0
IO46
Drop down
N/A
0
Enabling/Disabling ROM Code Print During Booting
3 4
Pin
Default
Print normally
No printing after
power-on
IO46
Drop down
See the description in
Article 4 for details
See the description in
Article 4 for details
Note:
1. The firmware can change the setting of "VDD_SPI voltage" after booting through the
configuration register.
2. GPIO 46 = 1 and GPIO0 = 0 cannot be used.
3. Since the operating voltage of the module's flash is 3.3 V by default (VDD_SPI output), the
internal IO45 pull-up resistor R1 of the module is not loaded by default. At the same time,
please pay attention to ensure that the external circuit will not pull IO45 high when the module
is powered on when using IO45.
4. The ROM Code power-on printing defaults to the TXD0 pin, which can be switched to the
DAC_1 (IO17) pin under the control of the eFuse bit.
5. The UART_PRINT_CONTROL of eFuse is:
When it is 0, it will print normally after power-on, and it is not controlled by IO46.
When 1, IO46 is 0: normal printing when power on; IO46 is 1: no printing when power on.
At 2 , IO46 is 0: no printing when power on; IO46 is 1: normal printing when power on.
At 3 , there is no printing after power on, and it is not controlled by IO46.
