Espressif Systems ESP32-H2 Series Instruction Manual

PRELIMINARY
ESP32-H2 Series
Hardware Design Guidelines
Introduction
Hardware design guidelines give advice on how to integrate ESP32-H2 into other products.
ESP32-H2 is a series of ultra-low-power SoCs with support for Bluetooth®5 (LE), Bluetooth
Mesh, Thread, Matter and Zigbee.
These guidelines will help to ensure optimal performance of your product with respect to tech-
nical accuracy and conformity to Espressif’s standards.
Pre-release v0.5
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PRELIMINARY
Contents
Contents
1 Overview 5
2 Schematic Checklist 6
2.1 Power Supply 7
2.1.1 Digital Power Supply 7
2.1.2 Analog Power Supply 7
2.2 Power-up Timing and System Reset 8
2.2.1 Power-up Timing 8
2.2.2 System Reset 8
2.2.3 Power-up and Reset Timing 9
2.3 Flash 9
2.4 Clock Source 9
2.4.1 External Clock Source (compulsory) 9
2.4.2 RTC Clock(optional) 11
2.5 RF 11
2.6 UART 12
2.7 Strapping Pins 13
2.8 GPIO 14
2.9 ADC 16
2.10 USB 16
3 PCB Layout Design 17
3.1 General Principles of PCB Layout 17
3.2 Positioning a Module on a Base Board 18
3.3 Power Supply 20
3.4 Crystal 21
3.5 RF 23
3.6 UART 25
3.7 USB 25
3.8 Typical Layout Problems and Solutions 25
3.8.1 Q: The voltage ripple is not large, but the TX performance of RF is rather poor. 26
3.8.2 Q: The voltage ripple is small, but RF TX performance is poor. 26
3.8.3 Q: When ESP32-H2 sends data packages, the power value is much higher or lower than the
target power value, and the EVM is relatively poor. 26
3.8.4 Q: TX performance is not bad, but the RX sensitivity is low. 27
4 Hardware Development 28
4.1 ESP32-H2 Modules 28
4.2 ESP32-H2 Development Boards 28
4.3 Download Guidelines 28
5 Related Documentation and Resources 30
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Contents
Glossary 31
Revision History 32
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List of Figures
List of Tables
1 Description of Timing Parameters for Power-up and Reset 9
2 Chip Boot Mode Control 13
3 Description of Timing Parameters for the Strapping Pins 13
4 IO MUX Pin Functions 14
List of Figures
1 ESP32-H2 Schematic 6
2 Schematic for the Digital Power Supply Pins 7
3 Schematic for the Analog Power Supply Pins 8
4 Visualization of Timing Parameters for Power-up and Reset 9
5 Schematic for the Crystal 10
6 Schematic for the RTC Clock 11
7 Schematic for RF Matching 12
8 RF Tuning Diagram 12
9 Visualization of Timing Parameters for the Strapping Pins 14
10 ESP32-H2 PCB Layout 17
11 Placement of ESP32-H2 Modules on Base Board (antenna feed point on the right) 18
12 Placement of ESP32-H2 Modules on Base Board (antenna feed point on the left) 19
13 Keepout Zone for ESP32-H2 Module’s Antenna on the Base Board 20
14 ESP32-H2 Power Traces in a Four-layer PCB Design 20
15 ESP32-H2 Crystal Oscillator Layout (Connected to the Ground) 22
16 ESP32-H2 Crystal Oscillator Layout (Not Connected to the Ground) 23
17 ESP32-H2 RF Layout in a Four-layer PCB Design 23
18 ESP32-H2 PCB Stack up Design 24
19 ESP32-H2 Stub in a Four-layer PCB Design 25
20 ESP32-H2 UART0 Layout 25
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PRELIMINARY
1 Overview
1 Overview
Note:
Check the link or the QR code to make sure that you use the latest version of this document:
https://espressif.com/sites/default/files/documentation/esp32-h2_hardware_design_guidelines_en.
pdf
ESP32-H2 series is a low-power MCU-based SoC solution that supports Bluetooth®5 (LE), Zigbee 3.0 and
Thread 1.3 (802.15.4). With its state-of-the-art power and RF performance, this SoC is an ideal choice for a wide
variety of application scenarios relating to Internet of Things (IoT), smart home, industrial automation, health care,
and consumer electronics.
ESP32-H2 has a 32-bit RISC-V processor, operating at up to 96 MHz. The chip supports application
development to operate without the need for a host MCU.
ESP32-H2 series provides a highly-integrated way to implement wireless communication technologies using a
complete RF subsystem, including a antenna switch, RF balun, power amplifier, low noise amplifier (LNA), filter,
power management unit, calibration circuits, etc. As a result, PCB size has been greatly reduced.
With its advanced calibration circuitry, ESP32-H2 series can dynamically adjust itself to remove external circuit
imperfections or adapt to changes in external conditions.
For more information about ESP32-H2 series, please refer to ESP32-H2 Series Datasheet.
Note:
Unless otherwise specified, “ESP32-H2” used in this document refers to the series of chips, instead of a specific chip
variant.
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2 Schematic Checklist
2 Schematic Checklist
The integrated circuitry of ESP32-H2 requires only 17 electrical components (resistors, capacitors, and inductors)
and one crystal. The high integration of ESP32-H2 allows for simple peripheral circuit design. This chapter details
ESP32-H2 schematics.
ESP32-H2 schematics are shown in Figure 1.
5
5
4
4
3
3
2
2
1
1
D D
C C
B B
A A
The values of C11, L2 and C12
vary with the actual PCB board.
The values of C1 and C4 vary with
the selection of the crystal.
The value of R4 varies with the
actual PCB board. R4 could be a
resistor or inductor, the initial
value is suggested to be 24 nH.
CHIP_EN:
H Activate chip;
L Disable chip.
This pin could not be float.
When VBAT is powered by external
battery, R2 can be NC.
RF_ANT LNA_IN GPIO27
GPIO0
GPIO2
GPIO3
GPIO1
GPIO4
GPIO5
VBAT
GPIO8 GPIO9 GPIO10 GPIO11 GPIO12 GPIO13
U0RXD
U0TXD
GPIO25
GPIO26
GPIO22
EN
GPIO14
GND
VDD33
GNDGNDGND
GND
GNDGND
GND
GND
GNDGND
GND
GND
VDD33
GND
GND
VDD33
VDD33
GND
VDD33
GND
VDD33
C2
10nF C5
1uF
C7
1uF
C10
0.1uF
C13
0.1uF
C6
10uF
L2 TBD
C1
TBD
R3 499
Y1
32MHz(±10ppm)
XIN
1
GND
2XOUT 3
GND 4
C19
0.1uF
ANT1
PCB_ANT
1
2
U1 ESP32-H2
VDD3P3
1
VDD3P3
2
GPIO0
3
GPIO1
4
MTMS
5
MTDO
6
MTCK
7
MTDI
8
GPIO8
10
GPIO9
11
GPIO10
12
GPIO11
13
GPIO12
14
XTAL_32K_P
15
XTAL_32K_N
16 GPIO26 25
GPIO27 26
VDD3P3 27
XTAL_N 28
XTAL_P 29
VDD3P3 30 VDD3P3 31
ANT 32
GND 33
VDDPST1
9
GPIO25 24
U0TXD 23
U0RXD 22
GPIO22 21
VDDPST2 20
VDDA_PMU 19
VBAT 18
CHIP_EN 17
C17
0.1uF
C12
TBD
R2 0
C8
0.1uF
C4
TBD
R4 TBD
C11
TBD
Figure 1: ESP32-H2 Schematic
Any basic ESP32-H2 circuit design may be broken down into 10 major sections:
• Power supply
• Power-on sequence and system reset
• Flash
• Clock source
• RF
• UART
• Strapping pins
• GPIO
• ADC
• USB
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The rest of this document details the specifics of circuit design for each of these sections.
2.1 Power Supply
For more information about power pins, please refer to ESP32-H2 Series Datasheet > Section Power Supply.
2.1.1 Digital Power Supply
ESP32-H2 has pin9 VDDPST1 and pin20 VDDPST2 that supply power to Group0 IO and Group1 IO respectively,
in a voltage range of 3.0 V ~3.6 V. It is recommended to add an extra 0.1 µF filter capacitor close to each digital
power supply pin.
The schematic for the digital power supply pins is shown in Figure 2.
5
5
4
4
3
3
2
2
1
1
D D
C C
B B
A A
The values of C11, L2 and C12
vary with the actual PCB board.
The values of C1 and C4 vary with
the selection of the crystal.
The value of R4 varies with the
actual PCB board. R4 could be a
resistor or inductor, the initial
value is suggested to be 24 nH.
CHIP_EN:
H Activate chip;
L Disable chip.
This pin could not be float.
When VBAT is powered by external
battery, R2 can be NC.
RF_ANT LNA_IN GPIO27
GPIO0
GPIO2
GPIO3
GPIO1
GPIO4
GPIO5
VBAT
GPIO8 GPIO9 GPIO10 GPIO11 GPIO12 GPIO13
U0RXD
U0TXD
GPIO25
GPIO26
GPIO22
EN
GPIO14
GND
VDD33
GNDGNDGND
GND
GNDGND
GND
GND
GNDGND
GND
GND
VDD33
GND
GND
VDD33
VDD33
GND
VDD33
GND
VDD33
C2
10nF C5
1uF
C7
1uF
C10
0.1uF
C13
0.1uF
C6
10uF
L2 TBD
C1
TBD
R3 499
Y1
32MHz(±10ppm)
XIN
1
GND
2XOUT 3
GND 4
C19
0.1uF
ANT1
PCB_ANT
1
2
U1 ESP32-H2
VDD3P3
1
VDD3P3
2
GPIO0
3
GPIO1
4
MTMS
5
MTDO
6
MTCK
7
MTDI
8
GPIO8
10
GPIO9
11
GPIO10
12
GPIO11
13
GPIO12
14
XTAL_32K_P
15
XTAL_32K_N
16 GPIO26 25
GPIO27 26
VDD3P3 27
XTAL_N 28
XTAL_P 29
VDD3P3 30 VDD3P3 31
ANT 32
GND 33
VDDPST1
9
GPIO25 24
U0TXD 23
U0RXD 22
GPIO22 21
VDDPST2 20
VDDA_PMU 19
VBAT 18
CHIP_EN 17
C17
0.1uF
C12
TBD
R2 0
C8
0.1uF
C4
TBD
R4 TBD
C11
TBD
Figure 2: Schematic for the Digital Power Supply Pins
2.1.2 Analog Power Supply
ESP32-H2’s pin1 VDD3P3, pin2 VDD3P3, pin18 VBAT, pin19 VDDA_PMU, pin27 VDD3P3, pin30 VDD3P3 and
pin31 VDD3P3 are the analog power supply pins, working at 3.0 V ~3.6 V.
For pin1 VDD3P3 and pin2 VDD3P3, it should be noted that the sudden increase in current draw, when
ESP32-H2 is transmitting signals, may cause a power rail collapse. Therefore, it is highly recommended to add
another 10 µF capacitor to the power trace, which can work in conjunction with the 1 µF capacitor and the 0.1
µF. Refer to Figure 3and place the appropriate decoupling capacitor near each analog power pin.
If VBAT is powered separately by an external power supply, R2 is not required and the operating voltage range is
3.0 V to 3.6 V.
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2 Schematic Checklist
5
5
4
4
3
3
2
2
1
1
D D
C C
B B
A A
The values of C11, L2 and C12
vary with the actual PCB board.
The values of C1 and C4 vary with
the selection of the crystal.
The value of R4 varies with the
actual PCB board. R4 could be a
resistor or inductor, the initial
value is suggested to be 24 nH.
CHIP_EN:
H Activate chip;
L Disable chip.
This pin could not be float.
When VBAT is powered by external
battery, R2 can be NC.
RF_ANT LNA_IN GPIO27
GPIO0
GPIO2
GPIO3
GPIO1
GPIO4
GPIO5
VBAT
GPIO8 GPIO9 GPIO10 GPIO11 GPIO12 GPIO13
U0RXD
U0TXD
GPIO25
GPIO26
GPIO22
EN
GPIO14
GND
VDD33
GNDGNDGND
GND
GNDGND
GND
GND
GNDGND
GND
GND
VDD33
GND
GND
VDD33
VDD33
GND
VDD33
GND
VDD33
C2
10nF C5
1uF
C7
1uF
C10
0.1uF
C13
0.1uF
C6
10uF
L2 TBD
C1
TBD
R3 499
Y1
32MHz(±10ppm)
XIN
1
GND
2XOUT 3
GND 4
C19
0.1uF
ANT1
PCB_ANT
1
2
U1 ESP32-H2
VDD3P3
1
VDD3P3
2
GPIO0
3
GPIO1
4
MTMS
5
MTDO
6
MTCK
7
MTDI
8
GPIO8
10
GPIO9
11
GPIO10
12
GPIO11
13
GPIO12
14
XTAL_32K_P
15
XTAL_32K_N
16 GPIO26 25
GPIO27 26
VDD3P3 27
XTAL_N 28
XTAL_P 29
VDD3P3 30 VDD3P3 31
ANT 32
GND 33
VDDPST1
9
GPIO25 24
U0TXD 23
U0RXD 22
GPIO22 21
VDDPST2 20
VDDA_PMU 19
VBAT 18
CHIP_EN 17
C17
0.1uF
C12
TBD
R2 0
C8
0.1uF
C4
TBD
R4 TBD
C11
TBD
Figure 3: Schematic for the Analog Power Supply Pins
Notice:
• When use the single power supply, the recommended power supply voltage for ESP32-H2 is 3.3 V and the output
current is no less than 350 mA.
• It is suggested to add another 10 µF capacitor at the power entrance. If the power entrance is close to pin1 and
pin2, it can share the same 10 µF capacitor with pin1 and pin2.
• It is suggested to add an ESD protection diode at the power entrance.
2.2 Power-up Timing and System Reset
2.2.1 Power-up Timing
When ESP32-H2 uses a 3.3 V system power supply, the power rails need some time to stabilize before CHIP_EN
is pulled up and the chip is enabled. Therefore, CHIP_EN needs to be powered up after the 3.3 V rails have been
brought up. More details about the power-up timing can be found in Section 2.2.3.
Notice:
To ensure the correct power-up timing, it is advised to add an RC delay circuit at the CHIP_EN pin. The recommended
setting for the RC delay circuit is usually R = 10 kΩand C = 1 µF. However, specific parameters should be adjusted based
on the characteristics of the actual power supply and the power-up and reset timing sequence of the chip.
2.2.2 System Reset
CHIP_EN serves as the reset pin of ESP32-H2. When CHIP_EN is at low level, the reset voltage (VIL_nRST )
should be in the range of (–0.3 ~0.25 × VDD) V. To avoid reboots caused by external interferences, make the
CHIP_EN trace as short as possible. Also, add a pull-up resistor as well as a capacitor to ground whenever
possible. More details can be found in Section 2.2.3.
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Notice:
CHIP_EN pin must not be left floating.
2.2.3 Power-up and Reset Timing
Figure 4shows the power-up and reset timing of ESP32-H2 series of chips. Details about the parameters are
listed in Table 1.
VIL_nRST
t0t1
2.8 V
Power Supply Pins
CHIP_EN
Figure 4: Visualization of Timing Parameters for Power-up and Reset
Table 1: Description of Timing Parameters for Power-up and Reset
Parameter Description Min (µs)
t0
Time between bringing up the power supply pins and activating
CHIP_EN 50
t1Duration of CHIP_EN signal level < VIL_nRST to reset the chip 50
Notice:
In cases where the power supply ramps up slowly (e.g., during battery charging), or the device needs to be frequently
powered on and off, or the power supply is unstable (e.g., in solar photovoltaic systems), adding a single RC circuit might
not meet the requirements for power-up and reset timing, and consequently the chip will not boot correctly. In this case,
it is advised to take other approaches, such as adding an external reset chip or a watchdog timer IC. The threshold of
reset chip or watchdog timer IC is suggested to be around 3.0 V.
2.3 Flash
ESP32-H2 series of chips have in-package 2 MB or 4 MB flash. The pins for flash are not bonded out.
2.4 Clock Source
ESP32-H2 has two clock sources:
• External clock source
• RTC clock source
2.4.1 External Clock Source (compulsory)
Currently, the ESP32-H2 firmware only supports 32 MHz crystal.
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Crystal
The circuit for the crystal is shown in Figure 5. Note that the accuracy of the selected crystal should be within
±10 ppm.
Please add a series component (resistor or inductor, see R4 in Figure 5) on the XTAL_P clock trace. Initially, it is
suggested to use an inductor of 24 nH to reduce the impact of high-frequency crystal harmonics on RF
performance, and the value should be adjusted after an overall test.
The initial values of external capacitors C1 and C4 can be determined according to the formula:
CL=C1×C4
C1 + C4+Cstray
where the value of CL(load capacitance) can be found in the crystal’s datasheet, and the value of Cstray refers to
the PCB’s stray capacitance. The values of C1 and C4 need to be further adjusted after an overall test as
below:
1. Select TX tone mode using the Certification and Test Tool.
2. Observe the 2.4 GHz signals with a radio communication analyzer or a spectrum analyzer and demodulate
it to obtain the actual frequency offset.
3. Adjust the frequency offset to be within ±10 ppm (recommended) by adjusting the external load
capacitance.
• When the center frequency offset is positive, it means that the equivalent load capacitance is small,
and the external load capacitance needs to be increased.
• When the center frequency offset is negative, it means the equivalent load capacitance is large, and
the external load capacitance needs to be reduced.
• External load capacitance at the two sides are usually equal, but in special cases, they may have
slightly different values.
5 5
4 4
3 3
2 2
1 1
D D C C B B A A
The values of C11, L2 and C12 vary with the actual PCB board.
The values of C1 and C4 vary with the selection of the crystal. The value of R4 varies with the actual PCB board. R4 could be a resistor or inductor, the initial value is suggested to be 24 nH.
CHIP_EN:
H Activate chip; L Disable chip. This pin could not be float.
When VBAT is powered by external battery, R2 can be NC.
RF_ANT LNA_IN GPIO27
GPIO0 GPIO2 GPIO3 GPIO1 GPIO4 GPIO5
VBAT
GPIO8
GPIO9
GPIO10
GPIO11
GPIO12
GPIO13
U0RXD U0TXD GPIO25 GPIO26 GPIO22 EN
GPIO14
GND
VDD33
GNDGNDGND
GND
GNDGND
GND
GND
GNDGND
GND
GND
VDD33
GND
GND
VDD33
VDD33
GND
VDD33
GND
VDD33
C2
10nF C5
1uF
C7
1uF
C10 0.1uF C13 0.1uF
C6
10uF
L2 TBD
C1
TBD
R3 499
Y1
32MHz(±10ppm)
XIN
1
GND
2XOUT 3
GND 4
C19 0.1uF
ANT1
PCB_ANT
1 2
U1 ESP32-H2
VDD3P3
1
VDD3P3
2
GPIO0
3
GPIO1
4
MTMS
5
MTDO
6
MTCK
7
MTDI
8
GPIO8
10
GPIO9
11
GPIO10
12
GPIO11
13
GPIO12
14
XTAL_32K_P
15
XTAL_32K_N
16 GPIO26 25
GPIO27 26
VDD3P3 27
XTAL_N 28
XTAL_P 29
VDD3P3 30
VDD3P3 31
ANT 32
GND 33
VDDPST1
9
GPIO25 24
U0TXD 23
U0RXD 22
GPIO22 21
VDDPST2 20
VDDA_PMU 19
VBAT 18
CHIP_EN 17
C17 0.1uF
C12
TBD
R2 0
C8
0.1uF
C4 TBD
R4 TBD
C11
TBD
Figure 5: Schematic for the Crystal
Notice:
• Defects in the manufacturing of crystal (for example, large frequency deviation of more than ±10 ppm, unstable
performance within operating temperature range, etc) may lead to the malfunction of ESP32-H2, resulting in a
decrease of the RF performance.
• It is recommended that the amplitude of the crystal is greater than 500 mV.
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