ESP8266 ESP-01S WiFi Serial Transceiver Module

Description:

comparing to ESP-01 (old version), ESP-01S (updated version) has these advantages:

The PCB layout has changed for an improvement in WiFi radio performance
1MB Flash Memory?upgraded from 512KB
Latest version esp-01s, with stronger signal
Feature

SDIO 2.0, SPI, UART
Four pins interface, VCC-3V3, GND, TXD and RXD. Two extra GPIOs can use.
AT commands firmware. New IC ESP8266ex
Wi-Fi Direct (P2P), soft-AP
Integrated TCP/IP protocol stack
Integrated TR switch, balun, LNA, power amplifier and matching network
Integrated PLLs, regulators, DCXO and power management units
+19.5dBm output power in 802.11b mode
Power down leakage current of <10uA
Integrated low power 32-bit CPU could be used as application processor
SDIO 1.1/2.0, SPI, UART
STBC, 1?1 MIMO, 2?1 MIMO
A-MPDU & A-MSDU aggregation & 0.4ms guard interval
Integrated RF switch, balun, 24dBm PA, DCXO, and PMU
Integrated RISC processor, on-chip memory and external memory interfaces
Integrated MAC/baseband processors
Quality of Service management
I2S interface for high fidelity audio applications
On-chip low-dropout linear regulators for all internal supplies
Proprietary spurious-free clock generation architecture
Integrated WEP, TKIP, AES, and WAPI engines
Specification:

802.11 b/g/n
Wake up and transmit packets in < 2ms
Standby power consumption of < 1.0mW (DTIM3)