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ESP-01S Wifi ESP8266 1MB Module
This is the upgradation of ESP-01 board, had small improvement on PCB.
This small board can act as WiFi module for Arduino (or other µc - Teensy, Netduino, etc) or as standalone microcontroller. With RISC processor running at 80 MHz and with 1MB Flash You can do lot interesting projects. It has 2 GPIO pins to interact with other modules (OneWire).
2 GPIO ports, each PWM capable
RISC processor 80MHz
power supply 3.3V
logic levels 3.3V
To program ESP You will need FTDI friend or USB/Serial converter. FTDI cable 3 V will work only if You provide other power source, FTDI cable, even 3V version has 5V at it's power line.


Power supply During start and in some working modes ESP takes up to 220 mA of current. Not all USB/Serial converters will provide such current. In that case You will need some separate 3.3V source to power module. More on ESP8266 current consumption topic. TL;DR: module takes from 220 mA in 802.11b mode, through 130mA - 150 mA in n or g modes to single mA in power save modes.


To program this module You can use LUA language, just upload nodeMCU firmware and You are ready to go :)


Features:
1MB (8Mbit) Flash size.
Very competitive price
AP, STA, AP+STA modes available.
Very simple AT commands, easy to use.
Internal LWIP interface.
Four pins interface, VCC-3V3, GND, TXD and RXD. Two extra GPIOs can use.
AT commands firmware. New IC ESP8266ex
ESP-01S  General DIP PTH version, less pin lead out, easy to use