ESP-WROOM-02 (32MBIT) WiFi, FTP, HTTP, IEEE 802.11b/g/n, IPv4,TCP, UDP, SMD

Description

ESP8266EX integrates a Tensilica L106 32-bit RISC processor, which achieves extra-low power consumption and reaches a maximum clock speed of 160 MHz. The Real-Time Operating System (RTOS) and Wi-Fi stack allow 80% of the processing power to be available for user application programming and development. The CPU includes the interfaces as below.

• Programmable RAM/ROM interfaces (iBus), which can be connected with memory controller, and can also be used to visit flash.
• Data RAM interface (dBus), which can connected with memory controller.
• AHB interface which can be used to visit the register.

Memory

Internal SRAM and ROM

ESP8266EX Wi-Fi SoC integrates memory controller and memory units including SRAM and ROM. MCU can access the memory units through iBus, dBus, and AHB interfaces. All memory units can be accessed upon request, while a memory arbiter will decide the running sequence according to the time when these requests are received by the processor. According to our current version of SDK, SRAM space available to users is assigned as below.

• RAM size < 50 kB, that is, when ESP8266EX is working under the Station mode and connects to the router, programmable space accessible in heap + data section is around 50 kB.
• There is no programmable ROM in the SoC, therefore, user program must be stored in an external SPI flash.

SPI Flash

ESP8266EX uses external SPI flash to store user programs, and supports up to 32 MB memory capacity . ESP-WROOM-02 supports these SPI modes: Standard SPI, DIO (Dual I/O), DOUT (Dual Output), QIO (Quad I/O) and QOUT (Quad Output).

Crystal Oscillator

ESP-WROOM-02 uses a 26-MHz crystal oscillator. The accuracy of the crystal oscillator should be ±10 PPM. When using the download tool, please select the right type of crystal oscillator. In circuit design, capacitors C1 and C2 which connect to the earth are added to the input and output terminals of the crystal oscillator respectively. The values of the two capacitors can be flexible, ranging from 6 pF to 22 pF, however, the specific capacitive values depend on further testing of, and adjustment to, the overall performance of the whole circuit. Normally, the capacitive values of C1 and C2 are within 10 pF for the 26-MHz crystal oscillator.

ESP-WROOM-02 Datasheet