Uart; Adc; Strapping Pins - Espressif Systems ESP32-C3 Series Hardware Design Manuallines

2 Schematic Checklist
VDD33
2.5 RF
C
In your circuit design, please add a π-matching network for antenna matching, preferably a CLC network.
GND
ANT1
PCB_ANT
B
Note:
The parameters of the components in the matching network are subject to the actual antenna and PCB layout.

2.6 UART

You need to connect a 499 Ω resistor to the U0TXD line to suppress the 80 MHz harmonics.

2.7 ADC

It is recommended to add a 0.1 µF filter capacitor between pins and ground when using the ADC function. ADC1 A
is more preferable.

2.8 Strapping Pins

Note:
The content below is excerpted from Section Strapping Pins in
ESP32-C3 family has three strapping pins:
• GPIO2
• GPIO8
• GPIO9
• GPIO10
Espressif Systems
C3
1uF
GND
L1 2.0nH
C5 C6
10uF 0.1uF
GND
RF_ANT
TBD
1 L2
2
C8
TBD TBD
GND GND
The values of C8, L2 and C9
vary with the actual PCB board.
 ‘ …‘’‘‡–
Figure 9: ESP32­C3 Family RF Matching Schematic
5
Submit Documentation Feedback
C4
100pF
GND
GND
C7
0.1uF
GND
LNA_IN
1
2
3
C9
GPIO0 4
GPIO1 5
GPIO2 6
CHIP_EN
7
GND
GPIO3 8
GPIO4
GPIO5
GPIO6
GPIO7
GPIO8
GPIO9
GPIO10
ESP32-C3 Family Datasheet.
11
ESP32-C3 Family Hardware Design Guidelines V0.5
LNA_IN
VDD3P3
VDD3P3
XTAL_32K_P
XTAL_32K_N
GPIO2
CHIP_EN
GPIO3
U2
4
R
24 R
SPIQ
23 R
SPID
22
R
SPICLK
21
SPICS0
20 R
SPIWP
19
R
SPIHD
18
VDD_SPI
17
VDD3P3_CPU
G
ESP32-C3
G