Espressif Systems ESP32-C3 Series - Page 15

2 Schematic Checklist
Table 4: IO MUX Pin Functions
Name No. Function 0 Function 1 Function 2 Reset Notes
XTAL_32K_P 4 GPIO0 GPIO0 — 0 R
XTAL_32K_N 5 GPIO1 GPIO1 — 0 R
GPIO2 6 GPIO2 GPIO2 FSPIQ 1 R
GPIO3 8 GPIO3 GPIO3 — 1 R
MTMS 9 MTMS GPIO4 FSPIHD 1 R
MTDI 10 MTDI GPIO5 FSPIWP 1 R
MTCK 12 MTCK GPIO6 FSPICLK 1* G
MTDO 13 MTDO GPIO7 FSPID 1 G
GPIO8 14 GPIO8 GPIO8 — 1 —
GPIO9 15 GPIO9 GPIO9 — 3 —
GPIO10 16 GPIO10 GPIO10 FSPICS0 1 G
VDD_SPI 18 GPIO11 GPIO11 — 0 —
SPIHD 19 SPIHD GPIO12 — 3 —
SPIWP 20 SPIWP GPIO13 — 3 —
SPICS0 21 SPICS0 GPIO14 — 3 —
SPICLK 22 SPICLK GPIO15 — 3 —
SPID 23 SPID GPIO16 — 3 —
SPIQ 24 SPIQ GPIO17 — 3 —
GPIO18 25 GPIO18 GPIO18 — 0 USB, G
GPIO19 26 GPIO19 GPIO19 — 0* USB
U0RXD 27 U0RXD GPIO20 — 1 G
U0TXD 28 U0TXD GPIO21 — 1 —
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)
• 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 (default), 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 DC
Characteristics (3.3 V, 25 °C) in ESP32-C3 Family Datasheet, or enable internal pull-up and pull-down resistors
during software initialization.
Notes
Espressif Systems 14
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ESP32-C3 Family Hardware Design Guidelines V0.5