Arduino-compatible IDE with ESP8266 support

This project brings support for ESP8266 chip to the Arduino environment. ESP8266WiFi library bundled with this project has the same interface as the WiFi Shield library, making it easy to re-use existing code and libraries.

Downloads

OS	Build status	Latest release
Linux		arduino-1.6.1-linux64.tar.xz
Windows		arduino-1.6.1-windows.zip
OS X		arduino-1.6.1-macosx-java-latest-signed.zip

Building from source

$ git clone https://github.com/esp8266/Arduino.git
$ cd Arduino/build
$ ant dist

Things that work

pinMode, digitalRead, digitalWrite, analogRead

Pin numbers correspond directly to the esp8266 GPIO pin numbers. To read GPIO2, call digitalRead(2);

GPIO0-GPIO15 can be INPUT, OUTPUT, INPUT_PULLUP, and OUTPUT_OPEN_DRAIN. GPIO16 can be INPUT or OUTPUT.

analogRead(0) reads the value of the ADC channel connected to the TOUT pin.

Pin interrupts (attachInterrupt, detachInterrupt)

Interrupts may be attached to any GPIO pin, except GPIO16. Standard Arduino interrupt types are supported: CHANGE, RISING, FALLING.

shiftIn, shiftOut

millis, micros

delay, delayMicroseconds, yield

Remember that there is a lot of code that needs to run on the chip besides the sketch when WiFi is connected. WiFi and TCP/IP libraries get a chance to handle any pending events each time the loop() function completes, OR when delay(...) is called. If you have a loop somewhere in your sketch that takes a lot of time (>50ms) without calling delay(), you might consider adding a call to delay function to keep the WiFi stack running smoothly.

There is also a yield() function which is equivalent to delay(0). The delayMicroseconds function, on the other hand, does not yield to other tasks, so using it for delays more than 20 milliseconds is not recommended.

Serial

Only 8n1 is supported right now. By default the diagnostic output from WiFi libraries is disabled when you call Serial.begin. To enable debug output again, call Serial.setDebugOutput(true);

WiFi(ESP8266WiFi library)

This is mostly similar to WiFi shield library. Differences include:

• WiFi.mode(m): set mode to WIFI_AP, WIFI_STA, or WIFI_AP_STA.
• call WiFi.softAP(ssid) to set up an open network
• call WiFi.softAP(ssid, passphrase) to set up a WPA2-PSK network
• WiFi.macAddress(mac) is for STA, WiFi.softAPmacAddress(mac) is for AP.
• WiFi.localIP() is for STA, WiFi.softAPIP() is for AP.
• WiFi.RSSI() doesn't work
• WiFi.printDiag(Serial); will print out some diagnostic info

WiFiServer, WiFiClient, and WiFiUDP behave mostly the same way as with WiFi shield library. Three samples are provided for this library.

Ticker

Library for calling functions repeatedly with a certain period. Two examples included.

EEPROM

This is a bit different from standard EEPROM class. You need to call EEPROM.begin(size) before you start reading or writing, size being the number of bytes you want to use. Size can be anywhere between 4 and 4096 bytes. EEPROM.write does not write to flash immediately, instead you must call EEPROM.commit() whenever you wish to save changes to flash. EEPROM.end() will also commit, and will release the RAM copy of EEPROM contents.

Three examples included.

I2C (Wire library)

Only master mode works, and I haven't tested if Wire.setClock gives correct frequency. Before using I2C, you need to set pins you will use for SDA and SCL by calling Wire.pins(int sda, int scl), i.e. Wire.pins(0, 2); on ESP-01.

OneWire (from https://www.pjrc.com/teensy/td_libs_OneWire.html)

Library was adapted to work with ESP8266 by including register definitions into OneWire.h Note that if you have OneWire library in your Arduino/libraries folder, it will be used instead of the one that comes with the Arduino IDE (this one).

mDNS responder (ESP8266mDNS library)

Allows the sketch to respond to multicast DNS queries for domain names like "foo.local". See attached example and library README file for details.

Other libraries that don't rely on low-level access to AVR registers.

• PubSubClient - sample

Upload via serial port

Select "esptool" as a programmer, and pick the correct serial port. You need to put ESP8266 into bootloader mode before uploading code (pull GPIO0 low and toggle power).

Things not done yet

• analogWrite (PWM). ESP8266 has only one hardware PWM source. It is not yet clear how to use it with analogWrite API. Software PWM is also an option, but apparently it causes issues with WiFi connectivity.
• pulseIn
• SPI. HSPI and bit-banging are two interfaces that will be supported.
• I2C slave mode
• Serial modes other than 8n1
• WiFi.RSSI. SDK doesn't seem to have an API to get RSSI for the current network. So far the only way to obtain RSSI is to disconnect, perform a scan, and get the RSSI value from there.
• Upload sketches via WiFi. Conceptually and technically simple, but need to figure out how to provide the best UX for this feature.
• Samples for all the libraries

License and credits

Arduino IDE is based on Wiring and Processing. It is developed and maintained by the Arduino team. The IDE is licensed under GPL, and the core libraries are licensed under LGPL.

This build includes an xtensa gcc toolchain, which is also under GPL.

Espressif SDK included in this build is under Espressif Public License.

Esptool written by Christian Klippel is licensed under GPLv2, currently maintained by Ivan Grokhotkov: https://github.com/igrr/esptool-ck.

ESP8266 core support, ESP8266WiFi, Ticker, ESP8266WebServer libraries were written by Ivan Grokhotkov, [email protected].