Datasheet

Table Of Contents
3 Functional Description
Reset
The default configuration of each pin after reset:
0 - input disabled, in high impedance state (IE = 0)
1 - input enabled, in high impedance state (IE = 1)
2 - input enabled, pull-down resistor enabled (IE = 1, WPD = 1)
3 - input enabled, pull-up resistor enabled (IE = 1, WPU = 1)
4 - output enabled, pull-up resistor enabled (OE = 1, WPU = 1)
0* - input disabled, pull-up resistor enabled (IE = 0, WPU = 0, USB_WPU = 1). See details in Notes
1* - When the value of eFuse bit EFUSE_DIS_PAD_JTAG is
0, input enabled, pull-up resistor enabled (IE = 1, WPU = 1)
1, input enabled, in high impedance state (IE = 1)
We recommend pulling high or low GPIO pins in high impedance state to avoid unnecessary power
consumption. You may add pull-up and pull-down resistors in your PCB design referring to Table 14, or enable
internal pull-up and pull-down resistors during software initialization.
Notes
R - These pins have analog functions.
USB - GPIO18 and GPIO19 are USB pins. The pull-up value of a USB pin is controlled by the pin’s pull-up
value together with USB pull-up value. If any of the two pull-up values is 1, the pin’s pull-up resistor will be
enabled. The pull-up resistors of USB pins are controlled by USB_SERIAL_JTAG_DP_PULLUP bit.
G - These pins have glitches during power-up. See details in Table 7.
Table 7: PowerUp Glitches on Pins
Typical Time Period
Pin Glitch
1
(ns)
MTCK Low-level glitch 5
MTDO Low-level glitch 5
GPIO10 Low-level glitch 5
U0RXD Low-level glitch 5
GPIO18 Pull-up glitch 50000
1
Low-level glitch: the pin is at a low level during the time period;
High-level glitch: the pin is at a high level during the time period;
Pull-up glitch: the pin is pulled up during the time period;
Pull-down glitch: the pin is pulled down during the time period.
3.4.2 Serial Peripheral Interface (SPI)
ESP32-C3 features three SPI interfaces (SPI0, SPI1, and SPI2). SPI0 and SPI1 can be configured to operate in
SPI memory mode, while SPI2 can be configured to operate in general-purpose SPI modes.
SPI Memory mode
In SPI memory mode, SPI0 and SPI1 interface with SPI memory. Data are transferred in unit of byte. Up to
four-line STR reads and writes are supported. The clock frequency is configurable to a maximum of 120
Espressif Systems 21
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ESP32-C3 Series Datasheet v1.2