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The ESP32-PICO-D4 is a highly integrated System-in-Package (SiP) module designed to simplify wireless embedded system development. This article will discuss the ESP32-PICO-D4 overview, pinout, functional block diagram, internal architecture, specifications, electrical characteristics, usage, applications, and mechanical dimensions.
The ESP32-PICO-D4 is a compact System-in-Package (SiP) module based on the ESP32 chipset. It integrates both Wi-Fi and Bluetooth connectivity in a single small package, allowing developers to build wireless systems with fewer external components. The module measures approximately 7 mm × 7 mm × 1 mm, helping reduce the required PCB space and simplifying hardware design.
Inside the package, the ESP32-PICO-D4 combines the ESP32 chip with several important components, including a 4-MB SPI flash memory, crystal oscillator, filter capacitors, and RF matching circuitry. This high level of integration improves design efficiency and reduces the need for additional parts on the board.
The module uses TSMC’s 40-nm ultra-low-power technology, offering reliable performance with efficient power consumption. Its integrated design also helps simplify the supply chain and manufacturing process. If you are interested in purchasing the ESP32-PICO-D4, feel free to contact us for pricing and availability.
| Pin | Name | Description |
| 1 | VDDA | Analog power supply for internal analog circuits |
| 2 | LNA_IN | RF input/output connection for antenna |
| 3 | VDDA3P3 | 3.3V analog power supply |
| 4 | VDDA3P3 | 3.3V analog power supply |
| 5 | SENSOR_VP | GPIO36, input pin for ADC and sensor signals |
| 6 | SENSOR_CAPP | Capacitive touch sensor input |
| 7 | SENSOR_CAPN | Capacitive touch sensor input |
| 8 | SENSOR_VN | GPIO39, ADC input pin |
| 9 | EN | Chip enable (reset control pin) |
| 10 | IO34 | GPIO34, input-only pin |
| 11 | IO35 | GPIO35, input-only pin |
| 12 | IO32 | GPIO32, general-purpose I/O |
| 13 | IO33 | GPIO33, general-purpose I/O |
| 14 | IO25 | GPIO25, DAC and general I/O |
| 15 | IO26 | GPIO26, DAC and general I/O |
| 16 | IO27 | GPIO27, general-purpose I/O |
| 17 | IO14 | GPIO14, SPI and general I/O |
| 18 | IO12 | GPIO12, SPI and general I/O |
| 19 | VDD3P3_RTC | RTC power supply |
| 20 | IO13 | GPIO13, general-purpose I/O |
| 21 | IO15 | GPIO15, SPI and general I/O |
| 22 | IO2 | GPIO2, boot configuration and general I/O |
| 23 | IO0 | GPIO0, boot mode selection |
| 24 | IO4 | GPIO4, general-purpose I/O |
| 25 | IO16 | GPIO16, UART and general I/O |
| 26 | VDD_SDIO | Power supply for SDIO interface |
| 27 | IO17 | GPIO17, UART and general I/O |
| 28 | SD2 | SPI flash data pin |
| 29 | SD3 | SPI flash data pin |
| 30 | CMD | SPI flash command pin |
| 31 | CLK | SPI flash clock pin |
| 32 | SD0 | SPI flash data pin |
| 33 | SD1 | SPI flash data pin |
| 34 | IO5 | GPIO5, SPI and general I/O |
| 35 | IO18 | GPIO18, SPI and general I/O |
| 36 | IO23 | GPIO23, SPI and general I/O |
| 37 | VDD3P3_CPU | CPU core power supply |
| 38 | IO19 | GPIO19, SPI and general I/O |
| 39 | IO22 | GPIO22, I²C and general I/O |
| 40 | U0RXD | UART0 receive pin |
| 41 | U0TXD | UART0 transmit pin |
| 42 | IO21 | GPIO21, I²C and general I/O |
| 43 | VDDA | Analog power supply |
| 44 | XTAL_N_NC | Crystal oscillator negative terminal (not connected internally) |
| 45 | XTAL_P_NC | Crystal oscillator positive terminal (not connected internally) |
| 46 | VDDA | Analog power supply |
| 47 | CAP2_NC | Internal capacitor pin (not connected externally) |
| 48 | CAP1_NC | Internal capacitor pin (not connected externally) |
| 49 | GND | Ground pad for electrical and thermal connection |
The ESP32-PICO-D4 functional block diagram shows the main internal modules integrated inside the chip. At the center is the processing system, which includes one or two Xtensa® 32-bit LX6 microprocessors, along with ROM and SRAM for program storage and data processing.
The diagram also includes Wi-Fi and Bluetooth subsystems, consisting of the Wi-Fi MAC, Wi-Fi baseband, Bluetooth controller, and Bluetooth baseband. These blocks connect to the RF transmit and receive circuits, clock generator, switch, and balun to manage wireless signal transmission and reception.
Several communication interfaces and peripherals are integrated, such as SPI, I²C, I²S, SDIO, UART, PWM, ADC, DAC, timers, and touch sensors. The chip also contains hardware cryptographic accelerators (AES, SHA, RSA, RNG) for security and an RTC subsystem with PMU and a ULP coprocessor to support low-power operation.
The ESP32-PICO-D4 contains two low-power Xtensa® 32-bit LX6 microprocessors that handle the main processing tasks of the system. It includes 448 KB of ROM used for booting and core system functions, and 520 KB of on-chip SRAM for storing program instructions and data. The chip also includes RTC FAST memory and RTC SLOW memory, which help maintain certain operations during low-power or deep-sleep modes. In addition, the device contains 1 Kbit of eFuse memory used for storing system configuration data such as the MAC address and security settings.
The ESP32-PICO-D4 supports external QSPI flash and SRAM for additional program and data storage. These memories can be accessed through high-speed cache to improve system performance. The module already integrates 4 MB of SPI flash, which stores firmware and application code.
The ESP32-PICO-D4 integrates a 40 MHz crystal oscillator that provides the clock signal required for internal processing and wireless communication functions.
The chip includes an RTC subsystem and advanced power-management system. These features allow the ESP32-PICO-D4 to switch between different power modes, helping reduce energy consumption while maintaining essential system operations.
The ESP32-PICO-D4 supports multiple peripheral interfaces and sensor connections for communication with external devices. Some pins such as IO16, IO17, CMD, CLK, SD0, and SD1 are reserved for the internal flash connection and are generally not recommended for other uses.
| Category | Parameter | Specification |
| MCU | Processor | Xtensa® dual-core 32-bit LX6 |
| Clock Speed | Up to 240 MHz | |
| ROM | 448 KB | |
| SRAM | 520 KB | |
| RTC Memory | 16 KB | |
| eFuse | 1 Kbit | |
| Wi-Fi | Standard | 802.11 b/g/n |
| Data Rate | Up to 150 Mbps | |
| Frequency Range | 2.412 – 2.484 GHz | |
| Features | A-MPDU, A-MSDU, 0.4 µs guard interval | |
| Bluetooth | Version | Bluetooth v4.2 BR/EDR + BLE |
| RF Class | Class 1, 2, 3 | |
| Sensitivity | -97 dBm (NZIF receiver) | |
| Features | AFH (Adaptive Frequency Hopping) | |
| Audio Codecs | CVSD, SBC | |
| Memory | Flash | 4 MB integrated SPI flash |
| External Support | QSPI Flash & SRAM supported | |
| Interfaces | Digital Interfaces | SPI, I²C, I²S, UART, SDIO |
| Analog Interfaces | ADC, DAC | |
| Others | PWM, Touch Sensor, RMT, Pulse Counter, TWAI® (CAN) | |
| Hardware Features | Security | AES, SHA, RSA, RNG |
| On-chip Sensor | Hall sensor | |
| Crystal Oscillator | 40 MHz integrated | |
| Power | Operating Voltage | 3.0 V – 3.6 V |
| Operating Current | ~80 mA (average) | |
| Min Supply Current | 500 mA (recommended source capability) | |
| Temperature | Operating Temperature | -40°C to +85°C |
| Physical | Dimensions | 7 mm × 7 mm × 1.1 mm |
| Package Type | System-in-Package (SiP) | |
| Moisture Sensitivity | MSL Level 3 | |
| Certifications | Bluetooth Certification | BQB |
| Category | Symbol | Parameter | Min | Typ | Max | Unit |
| Absolute Ratings | VDD33 | Power supply voltage | -0.3 | – | 3.6 | V |
| I_output | Cumulative IO output current | – | – | 1100 | mA | |
| T_store | Storage temperature | -40 | – | 85 | °C | |
| Recommended Conditions | VDD33 | Operating voltage | 3.0 | 3.3 | 3.6 | V |
| I_VDD | Supply current capability | 0.5 | – | – | A | |
| T | Operating temperature | -40 | – | 85 | °C | |
| Digital Input/Output | C_IN | Pin capacitance | – | 2 | – | pF |
| V_IH | High-level input voltage | 0.75×VDD | – | VDD+0.3 | V | |
| V_IL | Low-level input voltage | -0.3 | – | 0.25×VDD | V | |
| I_IH | High-level input current | – | – | 50 | nA | |
| I_IL | Low-level input current | – | – | 50 | nA | |
| V_OH | High-level output voltage | 0.8×VDD | – | – | V | |
| V_OL | Low-level output voltage | – | – | 0.1×VDD | V | |
| Drive Strength | I_OH | Output source current (CPU/RTC domain) | – | 40 | – | mA |
| I_OH | Output source current (SDIO domain) | – | 20 | – | mA | |
| I_OL | Output sink current | – | 28 | – | mA | |
| Internal Resistors | R_PU | Pull-up resistance | – | 45 | – | kΩ |
| R_PD | Pull-down resistance | – | 45 | – | kΩ | |
| Control Pin | V_IL_nRST | Low-level input (CHIP_PU) | – | – | 0.6 | V |
| Wi-Fi RF | – | Frequency range | 2412 | – | 2484 | MHz |
| – | Output impedance | – | 50 | – | Ω | |
| – | TX power (72.2 Mbps) | 13 | 14 | 15 | dBm | |
| – | TX power (11b) | 19.5 | 20 | 20.5 | dBm | |
| – | RX sensitivity (1 Mbps DSSS) | – | -98 | – | dBm | |
| – | RX sensitivity (54 Mbps OFDM) | – | -75 | – | dBm | |
| Bluetooth LE (Receiver) | – | Sensitivity | – | -97 | – | dBm |
| – | Max received signal | – | 0 | – | dBm | |
| – | Co-channel interference | – | +10 | – | dB | |
| Bluetooth LE (Transmitter) | – | RF transmit power | – | 0 | – | dBm |
| – | Power control range | -12 | – | +9 | dBm | |
| – | Frequency deviation (Δf1avg) | – | 265 | – | kHz | |
| – | Drift rate | – | 0.7 | – | kHz/50µs |
To utilize the ESP32-PICO-D4, you first need to provide a stable 3.3 V power supply and ensure proper grounding. Since the module already integrates flash memory, crystal oscillator, and RF components, only minimal external parts are required. You should connect the EN (enable) pin for reset control and use proper decoupling capacitors near the power pins to maintain stable operation.
Next, connect the necessary GPIO pins based on your design. The ESP32 supports multiple interfaces such as UART, SPI, I²C, and ADC, allowing flexible communication with external devices. Keep in mind that some pins (like IO16, IO17, and flash-related pins) are reserved internally and should not be used for general purposes.
For programming, you can use the UART interface along with development tools like the ESP-IDF or Arduino IDE. By configuring the firmware, you can control peripherals, manage communication protocols, and optimize performance. Proper PCB layout, especially for RF traces and grounding, is also important to ensure reliable operation.
• Smart home devices
• IoT sensor nodes
• Wearable electronics
• Wireless control systems
• Home automation systems
• Industrial monitoring systems
• Smart lighting systems
• Remote data logging devices
• Smart meters, etc.
| Symbol | Min (mm) | Nom (mm) | Max (mm) | Min (inch) | Nom (inch) | Max (inch) |
| A | 0.840 | 0.940 | 1.040 | 0.033 | 0.037 | 0.041 |
| c | 0.220 | 0.260 | 0.300 | 0.009 | 0.010 | 0.012 |
| D | 6.900 | 7.000 | 7.100 | 0.272 | 0.276 | 0.280 |
| E | 6.900 | 7.000 | 7.100 | 0.272 | 0.276 | 0.280 |
| D1 | 5.300 | 5.400 | 5.500 | 0.209 | 0.213 | 0.217 |
| E1 | 5.300 | 5.400 | 5.500 | 0.209 | 0.213 | 0.217 |
| H | — | 0.300 | — | — | 0.012 | — |
| H1 | — | 0.300 | — | — | 0.012 | — |
| L | 0.325 | 0.400 | 0.475 | 0.013 | 0.016 | 0.019 |
| L1 | 0.000 | 0.075 | 0.150 | 0.000 | 0.003 | 0.006 |
| e | — | 0.500 | — | — | 0.020 | — |
| b | 0.200 | 0.250 | 0.300 | 0.008 | 0.010 | 0.012 |
The ESP32-PICO-D4 is a powerful module that integrates essential wireless and processing features into a single package. Its dual-core processing, built-in memory, rich peripheral support, and advanced power management make it a versatile solution for efficient embedded system design. The detailed pinout, functional architecture, and electrical characteristics provide a clear understanding of how to use the module effectively in actual applications. With its small size, high integration, and reliable performance, the ESP32-PICO-D4 simplifies development while maintaining flexibility and scalability for modern electronic systems.
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