Datasheet

3 Pin Definitions
To change the strapping bit values, you can apply the external pull-down/pull-up resistances, or use the host
MCU’s GPIOs to control the voltage level of these pins when powering on ESP32-C3 family.
After reset, the strapping pins work as normal-function pins.
Refer to Table 3 for a detailed boot-mode configuration of the strapping pins.
Table 3: Strapping Pins
Booting Mode
1
Pin Default SPI Boot Download Boot
GPIO2 N/A 1 1
GPIO8 N/A Don’t care 1
GPIO9 Internal pull-up 1 0
Enabling/Disabling ROM Code Print During Booting
Pin Default Functionality
GPIO8 N/A
When the value of eFuse field EFUSE_UART_PRINT_CONTROL is
0 (default), print is enabled and not controlled by GPIO8.
1, if GPIO8 is 0, print is enabled; if GPIO8 is 1, it is disabled.
2, if GPIO8 is 0, print is disabled; if GPIO8 is 1, it is enabled.
3, print is disabled and not controlled by GPIO8.
1
The strapping combination of GPIO8 = 0 and GPIO9 = 0 is invalid and will trigger unexpected behavior.
Figure 4 shows the setup and hold times for the strapping pin before and after the CHIP_EN signal goes high.
Details about the parameters are listed in Table 4.
CHIP_EN
t
1
t
0
Strapping pin
V
IL_nRST
V
IH
Figure 4: Setup and Hold Times for the Strapping Pin
Table 4: Parameter Descriptions of Setup and Hold Times for the Strapping Pin
Min
Parameter Description
(ms)
t
0
Setup time before CHIP_EN goes from low to high 0
t
1
Hold time after CHIP_EN goes high 3
Espressif Systems 13
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ESP32-C3-WROOM-02 & WROOM-02U Datasheet v0.7