espressif ESP32-WROOM-32E Bluetooth Low Energy WiFi User Manual
Overview
ESP32 -WROOM -32E is a powerful, generic WiFi -BT -BLE MCU module that targets a wide variety of applications, ranging from low -power sensor networks to the most demanding tasks, such as voice encoding, music streaming and MP3 decoding. This is a SMD Module with 2.4 GHz PCB antenna on board. It reserves π tuning circuit for antenna impedance matching. It is with all GPIOs on the pin -out except the ones already used for connecting flash. The Module’s working voltage can be range from 3.0 V to 3.6 V. Frequency range is 2400 MHz to 2483.5 MHz. External 40 MHz as clock source for system. There is also a 4 MB SPI flash for storing user programs and data. The ordering information of ESP32 -WROOM -32E is listed as follows:
| Module | Chip embedded | Flash | PSRAM | Module dimensions (mm) |
| ESP32-WROOM-32E | ESP32-D0WD- V3 | 4 MB 1 | / | (18.00 ± 0.10) X (25.50 ± 0.10) X(3.10 ± 0.10) mm (including metallic shield) |
| Notes:1. ESP32-WROOM-32E (PCB) with 8 MB flash or 16 MB flash is available for custom order.2. For detailed ordering information, please see Espressif Product Ordering Information.3. For dimensions of the IPEX connector, please see Chapter 10. | ||||
At the core of the module is the ESP32 -D0WD -V3 chip*. The chip embedded is designed to be scalable and adaptive. There are two CPU cores that can be individually controlled, and the CPU clock frequency is adjustable from 80 MHz to 240 MHz. The user may also power off the CPU and make use of the low power co -processor to constantly monitor the peripherals for changes or crossing of thresholds. ESP32 integrates a rich set of peripherals, ranging from capacitive touch sensors, Hall sensors, SD card interface, Ethernet, highspeed SPI, UART, I²S and I²C
The operating system chosen for ESP32 is freeRTOS with LwIP; TLS 1.2 with hardware acceleration is built in as well. Secure (encrypted) over the air (OTA) upgrade is also supported, so that users can upgrade their products even after their release, at minimum cost and effort. Table 2 provides the specifications of ESP32 WROOM 32E.
Table 2: ESP32-WROOM-32E Specifications
| Categories | Items | Specifications |
| Test | Reliablity | HTOL/HTSL/uHAST/TCT/ESD |
Wi-Fi | Protocols | 802.11 b/g/n20/n40 |
| A-MPDU and A-MSDU aggregation and 0.4 s guard in-terval support | ||
| Frequency range | 2.412 GHz ~ 2.462GHz | |
Bluetooth | Protocols | Bluetooth v4.2 BR/EDR and BLE specification |
| Radio | NZIF receiver with –97 dBm sensitivity | |
| Class-1, class-2 and class-3 transmitter | ||
| AFH | ||
| Audio | CVSD and SBC | |
Hardware | Module interfaces | SD card, UART, SPI, SDIO, I2C, LED PWM, Motor PWM,I2S, IR, pulse counter, GPIO, capacitive touch sensor, ADC, DAC |
| On-chip sensor | Hall sensor | |
| Integrated crystal | 40 MHz crystal | |
| Integrated SPI flash | 4 MB | |
| Integrated PSRAM | – | |
| Operating voltage/Power supply | 3.0 V ~ 3.6 V | |
| Minimum current delivered bypower supply | 500 mA | |
| Recommended operating tem-perature range | –40 °C ~ 85 °C | |
| Package size | (18.00±0.10) mm × (31.40±0.10) mm × (3.30±0.10) mm | |
| Moisture sensitivity level (MSL) | Level 3 |
Pin Definitions
Pin Layout
Pin Description
ESP32 WROOM 32E has 38 pins. See pin definitions in Table 3.
| Name | No. | Type | Function |
| GND | 1 | P | Ground |
| 3V3 | 2 | P | Power supply |
| EN | 3 | I | Module-enable signal. Active high. |
| SENSOR_VP | 4 | I | GPIO36, ADC1_CH0, RTC_GPIO0 |
| SENSOR_VN | 5 | I | GPIO39, ADC1_CH3, RTC_GPIO3 |
| IO34 | 6 | I | GPIO34, ADC1_CH6, RTC_GPIO4 |
| IO35 | 7 | I | GPIO35, ADC1_CH7, RTC_GPIO5 |
| IO32 | 8 | I/O | GPIO32, XTAL_32K_P (32.768 kHz crystal oscillator input), ADC1_CH4,TOUCH9, RTC_GPIO9 |
| IO33 | 9 | I/O | GPIO33, XTAL_32K_N (32.768 kHz crystal oscillator output),ADC1_CH5, TOUCH8, RTC_GPIO8 |
| IO25 | 10 | I/O | GPIO25, DAC_1, ADC2_CH8, RTC_GPIO6, EMAC_RXD0 |
| IO26 | 11 | I/O | GPIO26, DAC_2, ADC2_CH9, RTC_GPIO7, EMAC_RXD1 |
| IO27 | 12 | I/O | GPIO27, ADC2_CH7, TOUCH7, RTC_GPIO17, EMAC_RX_DV |
| IO14 | 13 | I/O | GPIO14, ADC2_CH6, TOUCH6, RTC_GPIO16, MTMS, HSPICLK,HS2_CLK, SD_CLK, EMAC_TXD2 |
| IO12 | 14 | I/O | GPIO12, ADC2_CH5, TOUCH5, RTC_GPIO15, MTDI, HSPIQ,HS2_DATA2, SD_DATA2, EMAC_TXD3 |
| GND | 15 | P | Ground |
| IO13 | 16 | I/O | GPIO13, ADC2_CH4, TOUCH4, RTC_GPIO14, MTCK, HSPID,HS2_DATA3, SD_DATA3, EMAC_RX_ER |
| NC | 17 | – | – |
| NC | 18 | – | – |
| NC | 19 | – | – |
| NC | 20 | – | – |
| NC | 21 | – | – |
| NC | 22 | – | – |
| IO15 | 23 | I/O | GPIO15, ADC2_CH3, TOUCH3, MTDO, HSPICS0, RTC_GPIO13,HS2_CMD, SD_CMD, EMAC_RXD3 |
| IO2 | 24 | I/O | GPIO2, ADC2_CH2, TOUCH2, RTC_GPIO12, HSPIWP, HS2_DATA0,SD_DATA0 |
| IO0 | 25 | I/O | GPIO0, ADC2_CH1, TOUCH1, RTC_GPIO11, CLK_OUT1,EMAC_TX_CLK |
| IO4 | 26 | I/O | GPIO4, ADC2_CH0, TOUCH0, RTC_GPIO10, HSPIHD, HS2_DATA1,SD_DATA1, EMAC_TX_ER |
| IO16 | 27 | I/O | GPIO16, HS1_DATA4, U2RXD, EMAC_CLK_OUT |
| IO17 | 28 | I/O | GPIO17, HS1_DATA5, U2TXD, EMAC_CLK_OUT_180 – |
| IO5 | 29 | I/O | GPIO5, VSPICS0, HS1_DATA6, EMAC_RX_CLK |
| IO18 | 30 | I/O | GPIO18, VSPICLK, HS1_DATA7 |
Strapping Pins
ESP32 has five strapping pins, which can be seen in Chapter 6 Schematics:
- MTDI
- GPIO0
- GPIO2
- MTDO
- GPIO5
Software can read the values of these five bits from register ”GPIO_STRAPPING”
Each strapping pin is connected to its internal pull -up/pull -down during the chip reset. Consequently, if a strapping pin is unconnected or the connected external circuit is high -impedance, the internal weak pull -up/pull – down will determine the default input level of the strapping pins. To change the strapping bit values, users can apply the external pull -down/pull-up resistances, or use the host MCU’s GPIOs to control the voltage level of these pins when powering on ESP32. After reset release, the strapping pins work as normal -function pins. Refer to Table 4 for a detailed boot -mode configuration by strapping pins
| Booting Mode | |||||
| Pin | Default | SPI Boot | Download Boot | ||
| GPIO0 | Pull-up | 1 | 0 | ||
| GPIO2 | Pull-down | Don’t-care | 0 | ||
| Enabling/Disabling Debugging Log Print over U0TXD During Booting | |||||
| Pin | Default | U0TXD Active | U0TXD Silent | ||
| MTDO | Pull-up | 1 | 0 | ||
| Timing of SDIO Slave | |||||
| Pin | Default | Falling-edge SamplingFalling-edge Output | Falling-edge SamplingRising-edge Output | Rising-edge SamplingFalling-edge Output | Rising-edge SamplingRising-edge Output |
| MTDO | Pull-up | 0 | 0 | 1 | 1 |
| GPIO5 | Pull-up | 0 | 1 | 0 | 1 |
Note:
- Firmware can configure register bits to change the settings of ”Voltage of Internal LDO (VDD_SDIO)” and”Timing of SDIO Slave” after booting.
- Internal pull up resistor (R9) for MTDI is not populated in the module, as the flash and SRAM in ESP32 -32E only support a power voltage of 3.3 V (output by VDD_SDIO)
Functional Description
This chapter describes the modules and functions integrated in ESP32 -WROOM -32E
CPU and Internal Memory
ESP32 D0WD V3 contains two low power Xtensa ® 32 bit LX6 microprocessors. The internal memory includes: • 448 KB of ROM for booting and core functions.
- 520 KB of on chip SRAM for data and instructions.
- 8 KB of SRAM in RTC, which is called RTC FAST Memory and can be used for data storage; it is accessed by the main CPU during RTC Boot from the Deep sleep mode.
- 8 KB of SRAM in RTC, which is called RTC SLOW Memory and can be accessed by the co processor during the Deep sleep mode.
- 1 Kbit of eFuse: 256 bits are used for the system (MAC address and chip configuration) and the remaining 768 bits are reserved for customer applications, including flash -encryption and chip -ID.
External Flash and SRAM
ESP32 supports multiple external QSPI flash and SRAM chips. More details can be found in Chapter SPI in the ESP32 Technical Reference Manual . ESP32 also supports hardware encryption/decryption based on AES to pro -tect developers’ programs and data in flash. ESP32 can access the external QSPI flash and SRAM through high -speed caches.
- The external flash can be mapped into CPU instruction memory space and read -only memory space simul-taneously. – When external flash is mapped into CPU instruction memory space, up to 11 MB + 248 KB can be mapped at a time. Note that if more than 3 MB + 248 KB are mapped, cache performance will be reduced due to speculative reads by the CPU. – When external flash is mapped into read-only data memory space, up to 4 MB can be mapped at a time. 8 -bit, 16 -bit and 32 -bit reads are supported.
- External SRAM can be mapped into CPU data memory space. Up to 4 MB can be mapped at a time. 8- bit, 16 -bit and 32 -bit reads and writes are supported. ESP32 -WROOM -32E integrates a 4 MB SPI flash more memory space.
RTC and Low -Power Management
With the use of advanced power -management technologies, ESP32 can switch between different power modes. For details on ESP32’s power consumption in different power modes, pleas e refer to section ”RTC and Low – Power Management” in ESP32 User Manua
Peripherals and Sensors
Note:
External connections can be made to any GPIO except for GPIOs in the range 6 -11, 16, or 17. GPIOs 6 -11 are connected to the module’s integrated SPI flash. For details, please see Section 6 Schematics.
Electrical Characteristics
Absolute Maximum Ratings
Stresses beyond the absolute maximum ratings listed in the table below may cause permanent damage to the device. These are stress ratings only, and do not refer to the functional operation of the device that should follow the recommended operating conditions.
- The module worked properly after a 24-hour test in ambient temperature at 25 °C, and the IOs in three domains (VDD3P3_RTC, VDD3P3_CPU, VDD_SDIO) output high logic level to ground.
- Please see Appendix IO_MUX of ESP32 Datasheet for IO’s power
Recommended Operating Conditions
| Symbol | Parameter | Min | Typical | Max | Unit |
| VDD33 | Power supply voltage | 3.0 | 3.3 | 3.6 | V |
| IV DD | Current delivered by external power supply | 0.5 | – | – | A |
| T | Operating temperature | –40 | – | 85 | °C |
DC Characteristics (3.3 V, 25 °C)
| Symbol | Parameter | Min | Typ | Max | Unit | |
| CIN | Pin capacitance | – | 2 | – | pF | |
| VIH | High-level input voltage | 0.75×VDD1 | – | VDD1+0.3 | V | |
| VIL | Low-level input voltage | –0.3 | – | 0.25×VDD1 | V | |
| IIH | High-level input current | – | – | 50 | nA | |
| IIL | Low-level input current | – | – | 50 | nA | |
| VOH | High-level output voltage | 0.8×VDD1 | – | – | V | |
| VOL | Low-level output voltage | – | – | 0.1×VDD1 | V | |
| IOH | High-level source current (VDD1 = 3.3 V, VOH >= 2.64 V,output drive strength set to themaximum) | VDD3P3_CPU power domain 1; 2 | – | 40 | – | mA |
| VDD3P3_RTC power domain 1; 2 | – | 40 | – | mA | ||
| VDD_SDIO power domain 1; 3 | – | 20 | – | mA | ||
| Symbol | Parameter | Min | Typ | Max | Unit |
| IOL | Low-level sink current(VDD1 = 3.3 V, VOL = 0.495 V,output drive strength set to the maximum) | – | 28 | – | mA |
| RP U | Resistance of internal pull-up resistor | – | 45 | – | kΩ |
| RP D | Resistance of internal pull-down resistor | – | 45 | – | kΩ |
| VIL_nRST | Low-level input voltage of CHIP_PU to power off the chip | – | – | 0.6 | V |
Notes:
- Please see Appendix IO_MUX of ESP32 Datasheet for IO’s power domain. VDD is the I/O voltage for a particular power domain of pins.
- For VDD3P3_CPU and VDD3P3_RTC power domain, per-pin current sourced in the same domain is gradually reduced from around 40 mA to around 29 mA, VOH>=2.64 V, as the number of current-source pins increases.
- Pins occupied by flash and/or PSRAM in the VDD_SDIO power domain were excluded from the test.
Wi-Fi Radio
| Parameter | Condition | Min | Typical | Max | Unit |
| Operating frequency range note1 | – | 2412 | – | 2462 | MHz |
| RF Power | 802.11b:26dBm802.11g:25.42dBm802.11n20:25.48dBm802.11n40:25.78dBm | dBm | |||
| Sensitivity | 11b, 1 Mbps | – | –98 | – | dBm |
| 11b, 11 Mbps | – | –89 | – | dBm | |
| 11g, 6 Mbps | – | –92 | – | dBm | |
| 11g, 54 Mbps | – | –74 | – | dBm | |
| 11n, HT20, MCS0 | – | –91 | – | dBm | |
| 11n, HT20, MCS7 | – | –71 | – | dBm | |
| 11n, HT40, MCS0 | – | –89 | – | dBm | |
| 11n, HT40, MCS7 | – | –69 | – | dBm | |
| Adjacent channel rejection | 11g, 6 Mbps | – | 31 | – | dB |
| 11g, 54 Mbps | – | 14 | – | dB | |
| 11n, HT20, MCS0 | – | 31 | – | dB | |
| 11n, HT20, MCS7 | – | 13 | – | dB | |
Bluetooth/BLE Radio
| Parameter | Conditions | Min | Typ | Max | Unit |
| Sensitivity @30.8% PER | – | – | –97 | – | dBm |
| Maximum received signal @30.8% PER | – | 0 | – | – | dBm |
| Co-channel C/I | – | – | +10 | – | dB |
Adjacent channel selectivity C/I | F = F0 + 1 MHz | – | –5 | – | dB |
| F = F0 – 1 MHz | – | –5 | – | dB | |
| F = F0 + 2 MHz | – | –25 | – | dB | |
| F = F0 – 2 MHz | – | –35 | – | dB | |
| F = F0 + 3 MHz | – | –25 | – | dB | |
| F = F0 – 3 MHz | – | –45 | – | dB | |
Out-of-band blocking performance | 30 MHz ~ 2000 MHz | –10 | – | – | dBm |
| 2000 MHz ~ 2400 MHz | –27 | – | – | dBm | |
| 2500 MHz ~ 3000 MHz | –27 | – | – | dBm | |
| 3000 MHz ~ 12.5 GHz | –10 | – | – | dBm | |
| Intermodulation | – | –36 | – | – | dBm |
Transmitter
| Parameter | Conditions | Min | Typ | Max | Unit |
| RF Frequency | – | 2402 | – | 2480 | MHz |
| Gain control step | – | – | 3 | – | dBm |
| RF power control range | – | –12 | – | +10 | dBm |
| Adjacent channel transmit power | F = F0 ± 2 MHz | – | –52 | – | dBm |
| F = F0 ± 3 MHz | – | –58 | – | dBm | |
| F = F0 ± > 3 MHz | – | –60 | – | dBm | |
| ∆ f1avg | – | – | – | 265 | kHz |
| ∆ f2max | – | 247 | – | – | kHz |
| ∆ f2avg/∆ f1avg | – | – | –0.92 | – | – |
| ICFT | – | – | –10 | – | kHz |
| Drift rate | – | – | 0.7 | – | kHz/50 s |
| Drift | – | – | 2 | – | kHz |
Reflow Profile
Ramp -up zone — Temp.: <150 Time: 60 ~ 90s Ramp -up rate: 1 ~ 3 /s Preheating zone — Temp.: 150 ~ 200 Time: 60 ~ 120s Ramp -up rate: 0.3 ~ 0.8 /s
Reflow zone — Temp.: >217 7LPH60 ~ 90s; Peak Temp.: 235 ~ 250 (<245 recommended) Time: 30 ~ 70s
Cooling zone — Peak Temp. ~ 180 Ramp -down rate: -1 ~ -5 /s
Antenna Specifications
Dimensions:
Pattern Plots:
Revision History
| Date | Version | Release notes |
| 2020.02 | V0.1 | Preliminary release for certification CE& FCC. |
OEM Guidance
- Applicable FCC rules This module is granted by Single Modular Approval. It complies to the requirements of FCC part 15C, section 15.247 rules.
- The specific operational use conditions This module can be used in IoT devices. The input voltage to the module is nominally 3.3V-3.6 V DC. The operational ambient temperature of the module is -30 to 85 degree C. Only the embedded PCB antenna is allowed. Any other external antenna is prohibited.
- Limited module procedures N/A
- Trace antenna design N/A
- RF exposure considerations
The equipment complies with FCC radiation exposure limits set forth for an uncontrolled environment. The equipment has the additional RF exposure evaluation necessary for portable usage of the Bluetooth radio < 20cm between the radiator and body. For the change in the module’s RF exposure condition from mobile to portable, the Wi-Fi radio is disabled. - Antenna Antenna type: PCB antenna; Peak gain: 3.40dBi
- Label and compliance information An exterior label on OEM’s end product can use wording such as the following: “Contains Transmitter Module FCC ID: 2A9ZM-WROOM32E” or “Contains FCC ID: 2A9ZM-WROOM32E.”
- Information on test modes and additional testing requirements
a)The modular transmitter has been fully tested by the module grantee on the required number of channels,modulation types, and modes, it should not be necessary for the host installer to re-test all the available transmitter modes or settings. It is recommended that the host product manufacturer, installing the modular transmitter,perform some investigative measurements to confirm that the resulting composite system does not exceed the spurious emissions limits or band edge limits (e.g., where a different antenna may be causing additional emissions).
b)The testing should check for emissions that may occur due to the intermixing of emissions with the other transmitters, digital circuitry, or due to physical properties of the host product (enclosure). This investigation is especially important when integrating multiple modular transmitters where the certification is based on testing each of them in a stand-alone configuration. It is important to note that host product manufacturers should not assume that because the modular transmitter is certified that they do not have any responsibility for final product compliance.
c)If the investigation indicates a compliance concern the host product manufacturer is obligated to mitigate the issue. Host products using a modular transmitter are subject to all the applicable individual technical rules as well as to the general conditions of operation in Sections 15.5, 15.15, and 15.29 to not cause interference. The operator of the host product will be obligated to stop operating the device until the interference have been corrected . - Additional testing, Part 15 Sub part B disclaimer The final host / module combination need to be evaluated against the FCC Part 15B criteria for unintentional radiators in order to be properly authorized for operation as a Part 15 digital device.
FCC Warning:
Any Changes or modifications not expressly approved by the party responsible for compliance could void the user’s authority to operate the equipment. This device complies with part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) This device may not cause harmful interference, and (2) This device must accept any interference received, including interference that may cause undesired operation
Documents / Resources
 | espressif ESP32-WROOM-32E Bluetooth Low Energy WiFi [pdf] User Manual ESP32-WROOM-32E Bluetooth Low Energy WiFi, ESP32-WROOM-32E, Bluetooth Low Energy WiFi, Low Energy WiFi, Energy WiFi, WiFi |
