ESP32-Sx Family

The Espressif ESP32-S2 family is a series of low-power, single-core microcontrollers built on the Espressif IoT platform. They feature a highly integrated SoC (System on Chip) architecture, combining a CPU, WiFi connectivity, and various peripherals in a compact package. The ESP32-S2 chips are designed for IoT applications, smart home devices, wearables and more, offering enhanced security features, low power consumption, and support for various communication protocols. These microcontrollers are known for their cost-effectiveness and capabilities of connected devices. ESP32-S2 SoC is based on an Xtensa single-core 32-bit LX7 microcontroller with an additional ultra-low power (ULP) coprocessor with a Wi-Fi 2.4GHz radio and numerals peripherals. For now, the ESP32-S2 series includes the following chips in mass production:

• ESP32-S2 (figure 1) ,
  
• ESP32-S2F (figure 2) .
  

Figure 3 shows functional block diagram of ESP32-S2 chip^[1]. The main common features of the ESP32-S2 are:

Processors

• Main processor: • Xtensa® single-core 32-bit LX7 microprocessor, up to 240 MHz
  • Cores: 1
• Ultra low power coprocessor:
  • Cores: 1

Wireless connectivity

• WiFi: 802.11 b/g/n/(802.11n @ 2.4 GHz up to 150 Mbit/s) with simultaneous Infrastructure BSS Station mode/SoftApp mode/Promiscuous mode.

Memory: Internal memory

• ROM: 128 kB (for booting and core functions),
• SRAM: 320 kB (for data and instruction),
• RTC SRAM: 16 kB (for data storage and main CPU during RTC Boot from the deep-sleep mode),
• Embedded flash:
  • 0 MB (ESP32-S2, ESP32-S2R2 chips),
  • 2 MB (ESP32-S2FH2 chip),
  • 4 MB (ESP32S2FH4, ESP32FN4R2 chips).
• Embedded PSRAM:
  • 0 MB (ESP32-S2, ESP32-S2FH2, ESP32S2FH4 chips ),
  • 2 MB (ESP32FN4R2, ESP32-S2R2 chips ).

Peripheral Input/Output

• 43 programmable GPIOs,
• 2 × I²C (Inter-Integrated Circuit,
• 2 x UART (universal asynchronous receiver/transmitter),
• 4 × SPI (Serial Peripheral Interface),
• 1 × I²S (Integrated Inter-IC Sound),
• 1 x RMT (TX/RX),
• Motor PWM (pulse width modulation),
• LED PWM up to 8 channels,
• DMA controller,
• 1 x TWAI controller compatible with CAN Spec. 2.0,
• 4 x pulse counters,
• 1 x full-speed USB OTG,
• 1 x DVP 8/16 camera interface (I2S),
• 1 x LCD serial interface (SPI),
• 1 x LCD parallel interface.

Analog interfaces

• 2 x 13-bit ADCs up to 20 channels,
• 2 x 8-bit DACs,
• 14 x touch sensing GPIO,
• 1 x temperature sensor.

Security

• Secure boot,
• Flash encryption,
• IEEE 802.11 standard security features are all supported, including WFA, WPA/WPA2 and WAPI,
• 4096-bit OTP, up to 1792-bit for customers,
• Cryptographic hardware acceleration:
  • AES-128/192/256,
  • HMAC,
  • RSA,
  • random number generator (RNG).

The company also produces ready-made modules for easier implementation in user systems. These modules combines ESP32-S2 microcontroller and additional components mounted on PCB with EM shield ^[2](table 1):

For convenience, used by users of all skill levels, Espressif produces entry-level development boards using the ESP32-S2 SOCs. Those boards integrate complete Wi-Fi functions. Most ESP32-S2 I/O pins are broken out to the pin headers on both sides for easy interfacing. Users can connect peripherals with jumper wires or mount the development kit on a breadboard. Many different companies offer ready-made boards with processors. The original Espressif best-known small development boards are:

• ESP32-S2-DevkitM ^[3](figure 7) ,
  
• ESP32-S2-DevkitC ^[4](figure 8) ,
  

The ESP32-S3^[5][6] is an advanced version within Espressif S family, offering improved performance and expanded capabilities compared to its predecessors. ESP32-S3 is an MCU with a dual-core 32-bit Xtensa LX7 microprocessor, dual ULP coprocessors with Wifi 2.4 GHz and Bluetooth LE radio, and numerous useful peripherals. ESP32-S3 offers enhanced processing power, lower power consumption, and improved IoT and wireless connectivity application features. ESP32-S3 is designed for mobile systems, Industrial and Home Automation, Health Care devices, Touch and Proximity Sensing, wearable electronics, and Internet-of-Things (IoT) applications. In addition, ESP32-S3 includes support for vector instructions in the MCU, which provides acceleration for neural network computing and signal processing workloads. The ESP32-S3 is the first low-cost microcontroller with a built-in peripheral that can drive TTL displays, and it can come with enough PSRAM to buffer those large images. For now, the ESP32-S3 family includes the following chips in mass production:

• ESP32-S3 (figure 9) ,
  
• ESP32-S3-Pico-1 (figure 10).
  

Figure 11 shows a functional block diagram of the ESP32-S3 chip. ESP32-S3's main common features of the ESP32-S3 are:

Processors

• Main processor: • Xtensa® dual-core 32-bit LX7 microprocessor, up to 240 MHz:
  • Cores: 2
• Ultra low power coprocessor:
  • Cores: 2
  • ULP-RISC-V coprocessor - based on RISC-V instruction set architecture:
    
    • Support for RV32IMC instruction set,
    • Thirty-two 32-bit general-purpose registers,
    • 32-bit multiplier and divider,
    • Support for interrupts,
    • Booted by the CPU, its dedicated timer, or RTC GPIO.
  • ULP-FSM coprocessor - based on finite state machine:
    • Support for common instructions, including arithmetic, jump, and program control instructions,
    • Support for on-board sensor measurement instructions,
    • Booted by the CPU, its dedicated timer, or RTC GPIO.

Wireless connectivity

• WiFi: 802.11 b/g/n/mc (802.11n @ 2.4 GHz up to 150 Mbit/s) with simultaneous Infrastructure BSS Station mode/SoftApp mode/Promiscuous mode.
• Bluetooth:
  • Low Energy Bluetooth 5, Bluetooth mesh,
  • Speed 125kbps, 500 kbps, 1 Mbps, 2 Mbps,
  • Internal sharing antenna with WiFi.

Memory: Internal memory:

• ROM: 384 kB (booting and core functions),
• SRAM: 512 kB (for data and instruction),
• RTC SRAM: 16 kB (for data storage and main CPU during RTC Boot from the deep-sleep mode),
• Embedded flash:
  • 0 MB (ESP32-S3, ESP32-S3R2, ESP32-S3R8, ESP32-S3R8V chips),
  • 4 MB (ESP32-S3FH4R2 chip),
  • 8 MB (ESP32-S3FN8 chip).
• Embedded PSRAM:
  • 0 MB (ESP32-S3, ESP32-S3FN8 chips ),
  • 2 MB (ESP32-S3R2, ESP32-S3FH4R2 chips ),
  • 8 MB (ESP32-S3R8, ESP32-S3R8V chips ).

Peripheral Input/Output:

• 45 programmable GPIOs,
• 2 × I²C (Inter-Integrated Circuit,
• 3 x UART (universal asynchronous receiver/transmitter),
• 4 × SPI (Serial Peripheral Interface),
• 2 × I²S (Integrated Inter-IC Sound),
• 1 x RMT (TX/RX),
• Motor PWM (pulse width modulation),
• LED PWM up to 8 channels,
• DMA controller with 5 transmit and 5 receive channels,
• 1 x TWAI controller compatible with CAN Spec. 2.0,
• 4 x pulse counters,
• 1 x full-speed USB OTG,
• 1 × USB Serial/JTAG controller,
• 1 x DVP 8/16 camera interface (I2S),
• 1 x LCD parallel interface,
• 1 × SD/MMC host controller.

Analog interfaces:

• 2 x 12-bit ADCs up to 20 channels,
• 14 x touch sensing GPIO,
• 1 x temperature sensor.

Low power management:

• Power Management Unit with five power modes,
• Ultra-low-power (ULP) coprocessors.

Security:

• Secure boot,
• Flash encryption,
• IEEE 802.11 standard security features are all supported, including WFA, WPA/WPA2 and WAPI,
• 4096-bit OTP, up to 1792-bit for customers,
• Cryptographic hardware acceleration:
  • AES-128/192/256,
  • Hash (FIPS PUB 180-4),
  • HMAC,
  • RSA,
  • Digital signature,
  • random number generator (RNG).

ESP32-S3-PICO-1 has all the functions of ESP32-S3 but integrates all peripheral components, including a crystal oscillator, decoupling capacitors, SPI flash/PSRAM, and RF matching links, within a single package. Figure 12 shows a functional block diagram of the ESP32-S3-PICO-1 chip.

The company also produces ready-made modules^[7][8][9]for easier implementation in user systems. These modules combine ESP32-S2 microcontroller, antenna and additional components mounted on PCB with EM shield ^[10] (table 2):

To facilitate the use of ESP32-S3, Espressif and other companies produce different development kits to suit different needs and present different processor functions. The original Espressif best-known small development boards are:

• ESP32-S3-DevkitM,
• ESP32-S3-DevkitC,
• ESP32-S3-BOX-3,
• ESP32-S3-BOX,
• ESP32-S3-EYE,
• ESP32-S3-Korvo-1,
• ESP32-S3-Korvo-2,
• ESP32-S3-LCD-Ev-Board.

For this book, we present only a few of the most popular, universal for various applications development boards:

• ESP32-S3-DevkitM(figure 16) ,
  
• ESP32-S3-DevkitC(figure 17) ,
  
• Waveshare ESP32-PICO-1^[11] (figure 18),
• M5Stamp-S3^[12] (figure 19).

Table 3 provides a brief comparison of the most essential features of the ESP32-S2 & ESP32-S3 systems^[13]