4G Wifi Module SMD Module ESP-WROOM-02 With Best RF Performance

Espressif provides the SMD module—ESP-WROOM-02 that integrates ESP8266EX. The module has been adjusted to get the best RF performance. We recommend using ESPWROOM-02 for tests or for further development.

The module size is (18.00±0.10) mm x (20.00±0.10) mm x (2.80±0.10) mm. The type of flash used on this module is an SPI flash with a package size of SOP 8-150 mil. The gain of the on-board PCB antenna is 2 dBi.

MCU

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.

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 16 MB memory capacity theoretically. ESP-WROOM-02 currently integrates a 2-MB SPI flash. ESP-WROOM-02 supports these SPI modes: Standard SPI, DIO (Dual I/O), DOUT (Dual Output), QIO (Quad I/O) and QOUT (Quad Output).