Espressif provides the SMD module—ESP-WROOM-S2 that integrates ESP8266EX. The module has been adjusted to achieve the best RF performance. We recommend using ESP-WROOM-S2 for tests or for further development. The flash used on this module is a 2-MB SPI flash connected to HSPI, with a package size of SOP 8-150 mil. The gain of the on-board PCB antenna is 2 dBi. The ESP-WROOM-S2 works as the SDIO/SPI slave with the SPI speed of up to 8 Mbps.
ESP8266EX contained in the ESP-WROOM-S2 integrates Tensilica L106 32-bit microcontroller (MCU) and a 16-bit RSIC. The CPU clock speed is 80 MHz and can reach a maximum value of 160 MHz. The system can readily run a Real-Time Operating System (RTOS). Currently, the Wi-Fi stack only takes up 20% of CPU time. The remaining CPU time (80% of total MIPS) can be used for user applications. The MCU can work in conjunction with the other parts of the chip through the following interfaces.
- Programmable RAM/ROM interface (iBus) that connects to the memory controller and can access the external flash.
- Data RAM interface (dBus) that connects to memory controller.
- AHB interface that accesses the register.
ESP8266EX Wi-Fi SoC integrates the memory controller including ROM and SRAM. MCU can access the memory controller through iBus, dBus, and AHB interfaces. All these interfaces can access ROM or RAM units. A memory arbiter determines the running sequence in the arrival order of requests.
According to our current version of SDK, SRAM space available to users is assigned as follows.
- RAM size < 50 kB, that is, when ESP8266EX is working in Station mode and connects to the router, available space in the Heap + Data sector is around 50 kB.
- There is no programmable ROM in ESP8266EX, therefore, user program must be stored in the SPI flash integrated into the ESP-WROOM-S2.
ESP8266EX supports SPI flash. Theoretically speaking, ESP8266EX can support an upto 16 MB SPI flash.
ESP-WROOM-S2 currently integrates a 2-MB SPI flash. ESP-WROOM-S2 supports these SPI modes: Standard SPI, DIO (Dual I/O), DOUT (Dual Output), QIO (Quad I/O) and QOUT (Quad Output).
Key Benefits
- 2.4 GHz Wi-Fi module
- Tensilica L106 integrated 32-bit RISC processor for ultra-low power consumption and reaches a maximum clock frequency of 160 MHz.
- Support IEEE 802.11 b/g/n standards
- Wi-Fi mode: Station/SoftAP/SoftAP + Station
- Size 16 mm x 23 mm x 2.8 mm
- Operating ambient temperature –40 °C ~ 85 °C
- Green certification RoHS/REACH
