Crystal Oscillator; External Clock Source (Compulsory) - Espressif Systems ESP32-S2 Hardware Design Manuallines

2. Schematic Checklist
C10
0.1uF
GND
42
GPIO38
41
GPIO37
40
GPIO36
39
GPIO35
38
GPIO34
37
GPIO33
36 R13
SPID
35
R14
SPIQ
34 R10
SPICLK
33
SPICS0
32
R15
SPIWP
31
R16
SPIHD
30
VDD_SPI
29
SPICS1
C13
ESP32-S2 0.1uF
GND
R11 10K
C16
0.1uF
GND
3

2.4 Crystal Oscillator

There are two clock sources for the ESP32-S2, that is, an external crystal oscillator clock source and an RTC clock
source.

2.4.1 External Clock Source (compulsory)

Currently, the ESP32-S2 firmware only supports 40 MHz crystal oscillator. The specific capacitive values of C1 and
C4 depend on further testing of, and adjustment to, the overall performance of the whole circuit. It is recommended
that users reserve a series resistor (a 0 Ω resistor can be used initially) on the XTAL_P clock trace to reduce the
drive strength of the crystal, as well as to minimize the impact of crystal harmonics on RF performance. Note that
the accuracy of the selected crystal is ±10 ppm.
Figure 5 and Figure 6 show the schematics for crystal and crystal oscillator in ESP32-S2.
Espressif Systems
GPIO45
U0RXD
U0TXD
R3 499
GPIO42
GPIO41
GPIO40
GPIO39
VDD33
GPIO38
GPIO37
GPIO36
GPIO35
GPIO34
GPIO33
0 SPID
0 SPIQ
0 SPICLK
SPICS0
0 SPIWP
SPIHD
0
GPIO26 SPICS1
VDD_SPI
C14
1uF
GND
VDD33
Figure 4: ESP32­S2 Flash and SRAM
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R8
10K(NC)
U2
SPICS0 1
/CS
SPICLK 6
CLK
SPIHD 7
/HOLD
NC: No component.
R9
10K(NC)
U3
1
SPICS1
CS
SPICLK 6
SCLK
SPIHD 7
SIO3
2
6 ESP32-S2 Hardware Design Guidelines V1.1
VDD_SPI
5 SPID
DI
2 SPIQ
DO
3 SPIWP
/WP
FLASH-3V3
GND
VDD_SPI
5
SPID
SI/SIO0
2 SPIQ
SO/SIO1
3 SPIWP
SIO2
(Optional)
PSRAM-3V3
GND
1
C
B
A