Scripts, notes and the odd fish for the ESP8266

Hamish Cunningham, Gareth Coleman, and Crowds.Work

A small corner of The Commons

("Tragedy?!" That was bad science!)

Note: the Lua code uses NodeMCU. This is a great firmware for the ESP8266, but sometimes struggles with the resource constraints of the device. It is also quite a lot of work to port existing Arduino code for the sensors etc. that we're using over to Lua. So the new stuff now uses the ESP Arduino IDE (forum).

• A Lua port of code for the TSL2561 I2C Luminosity sensor.
• A library for configuring the ESP8266 over the air to join existing wifi networks (and later version WeGrow.
• Code exhibiting memory size limits on the ESP.
• A (failed) attempt to abstract the control regime of joinme, Control Freak.
• Arduino-style libraries and sketches for an ESP-based sensor/actuator board: ARDESP.

This is all AGPL 3. Like it or lump it :-)

## Developing on the ESP8266 with NodeMCU

• check out this tree including its submodules (third-party dependencies)
  • git clone --recursive git@github.com:hamishcunningham/fishy-wifi.git
• the Makefile assumes you've either checked out and rebuilt the open source SDK (see below), or -- if you're on 64 bit Linux -- you're using the local copy in ./esp8266-local-sdk
• there are targets for
  • rebuilding the NodeMCU firmware (inc. with or without a DNS server)
    • make nodemcu[-with-dns]
  • flashing the firmware (inc. to several choices of board)
    • pull the relevant ESP pin low; cycle chip enable (or do a hard reset; the Olimex board always seems to require a hard reset) -- see below
    • make flashnodemcu (for e.g. the ESP01 or other board with small flash)
    • make flasholimex (for e.g. the Olimex, 2MB flash)
    • disconnect the flashing pin and cycle chip enable (or hard reset) again
• running the ESPlorer development tool
  • to pick up a set of useful code snippets, run make seed-esplorer-prefs
  • to run ESPlorer make esplorer
  • then do a scan, port open, etc.
• uploading Lua code and experimenting
  • have a poke around in e.g. the JoinMe code (below)
  • open the .lua files in ESPlorer and save them to the ESP
  • restart the board and off you go (details here)
• running the MQTT Spy tool: make mqtt-spy

If you're using a breadboard from me with a DIP switch, you can fiddle with the flashing pin and chip enable via that switch:

Flashing is enabled by setting switch 1 to on; chip enable is switch 5.

How to...

(Note: some of these are superseded by the above...)

Build open source toolchain:

• instructions from http://nathan.chantrell.net/20141230/wifi-mqtt-display-with-the-esp8266/
• sudo apt-get install make unrar autoconf automake libtool gcc g++ gperf flex bison texinfo gawk ncurses-dev libexpat-dev python python-serial sed
• cd esp-open-sdk
• make STANDALONE=n
  • Xtensa toolchain is built, to use it:
  • export PATH=${HOME}/fishy-wifi/esp8266-local-sdk/esp-open-sdk/xtensa-lx106-elf/bin:$PATH
  • TODO is this nesc?
    • Espressif ESP8266 SDK is installed. Toolchain contains only Open Source components To link external proprietary libraries add:
    • xtensa-lx106-elf-gcc -I${HOME}/fishy-wifi/esp8266-local-sdk/esp-open-sdk/sdk/include -L${HOME}/fishy-wifi/esp8266-local-sdk/esp-open-sdk/sdk/lib`

Rebuild NodeMCU:

cd nodemcu-firmware
PATH=${PATH}:${HOME}/fishy-wifi/esp8266-local-sdk/esp-open-sdk/xtensa-lx106-elf/bin make

Flash the firmware to the ESP8266:

cd app
make flashnodemcu

or, for the Olimex board:

make flasholimex

Older methods:

.../esptool.py --port /dev/ttyAMA0 write_flash 0x00000
  ../bin/0x00000.bin 0x10000 ../bin/0x10000.bin 0x7E000 ../bin/blank.bin
  0x7C000 ../bin/esp_init_data_default.bin
.../esptool.py --port /dev/ttyAMA0 write_flash 0x00000 ../nodemcu_512k_latest.bin

Rebuild ESPlorer:

ant -Dplatforms.JDK1.7.home=/usr/lib/jvm/jdk-8-oracle-arm-vfp-hflt/ jar

Connect via picocom:

(first disable getty on /dev/ttyAMA0 via /etc/inittab)
picocom /dev/ttyAMA0 --omap crcrlf
(then toggle DTR to get elua prompt)

Picocom commands:

^A plus...
^T toggle DTR line
^U baud rate up (^D for down)

Wiring the ESP01 breadboard:

• red vcc
• black module gnd
• brown module rx
• gpio0
• black gnd
• white tx

Wiring the Olimex board:

• gpio 1 & 3 are rxt and txt
• need gpio 15 low and cp_en high
• to flash hold gpio0 low -- sometimes I think it doesn't float high so might try using 4.7k resistor to connect it to high?
• to get normal mode after flashing perhaps most useful

Luatool filetransfer thingy:

${HOME}/fishy-wifi/esp8266-local-sdk/luatool/luatool/luatool.py -p /dev/ttyAMA0 -f init.lua -t init.lua -v

Resources

• ESP8266 BB: http://www.esp8266.com/
• Wiki: https://github.com/esp8266/esp8266-wiki/wiki/
• NodeMCU: http://nodemcu.com/index\_en.html
• File API: https://raw.githubusercontent.com/nodemcu/nodemcu-firmware/master/app/modules/file.c
• Why not worth bothering with ad hoc Javascript PK encryption (do HTTPS instead): http://matasano.com/articles/javascript-cryptography/
• Chip datasheet: https://nurdspace.nl/images/e/e0/ESP8266\_Specifications\_English.pdf
• Nurdspace notes: https://nurdspace.nl/ESP8266
• Espressif BB: http://bbs.espressif.com/
• Olimex: https://www.olimex.com/Products/IoT/MOD-WIFI-ESP8266-DEV/