ESP8266 and MicroPython

Nick Moore
@mnemote

ESP8266

original image: zeptobars.com

original image: zeptobars.com

Originally came to prominence as a WiFi controller for AVR and similar, but ...

AVR (Arduino)	ESP8266	ARM / Broadcom (RPi 2)
ATMega328P	Tensilica Xtensa LX106	Cortex A53
8 bit	32 bit	32 bit
1 core	1 core	4 core
20 MHz	80-160 MHz	900 MHz
2KB RAM	160KB RAM	1GB RAM
32KB Flash	DIO/QIO Flash	MicroSDHC

Modules — 1

image: Random Nerd Tutorials

Modules — 2

source images: itead.cc

not the ESP-14, which is very different

original image: adafruit.com

original image: adafruit.com

Programming the ESP8266

• Serial programming mode to flash memory
  by pulling GPIO0 low at reset
• Any of the usual RS232-TTL converters
• 3.3v at 250mA ...
• ... bad power gives unpredictable results!

The easy way ... NodeMCU

• 3.3v regulator
• USB to serial interface
• Automatic flash &
  reset functions
• Standard 0.1" headers
• $8-$10 on Ebay

Other Boards

esptool

github: themadinventor/esptool

$ git clone https://github.com/themadinventor/esptool.git

or

$ pip install esptool

or

$ apt install esptool

esp-open-sdk — 1

github: pfalcon/esp-open-sdk

• C development using GCC toolchain
• "Free and open (as much as possible)"
• Includes some binary blobs from Espressif

Other Languages

• Lua: Node Lua
• Javascript: Espruino, Cesanta V7 ...
• Forth, Lisp, Basic

... and thanks to a successful Kickstarter campaign and Damien George ...

MicroPython

micropython.org

Getting MicroPython

• Git Repo: https://github.com/micropython/micropython.git
• Download firmware from https://micropython.org/download#esp8266

Use esptool to load onto board:

$ export ESPTOOL_PORT=/dev/ttyUSB0
$ export ESPTOOL_BAUD=115200
$ export ESPTOOL_FS=32m
$ esptool write_flash 0 esp8266-20161110-v1.8.6.bin

MicroPython REPL

$ cu -l /dev/ttyUSB0 -s 115200
MicroPython v1.8.6-7-gefd0927 on 2016-11-10; ESP module with ESP8266
Type "help()" for more information.
>>> dir()
['uos', '__name__', 'webrepl', 'gc', 'bdev', 'vfs']
>>> print("Hello, World!")
Hello, World!
>>>

MicroPython I/O — 1

>>> import machine
>>> import time
>>> pin2 = machine.Pin(2)
>>> pin2.init(machine.Pin.OUT)
>>> while True:
...     pin2.low()
...     time.sleep(0.5)
...     pin2.high()
...     time.sleep(0.5)

MicroPython I/O — 2

class Servo:
    def __init__(self, pin):
        self.pwm = machine.PWM(machine.Pin(pin))
        self.pwm.freq(50)

    def set(self, pos):
        pulse_us = 1000 + 1000 * min(1,max(pos,0))
        self.pwm.duty(int(pulse_us * self.pwm.freq() * 0.001024))

MicroPython WiFi

>>> import network
>>> sta_if = network.WLAN(network.STA_IF)
>>> sta_if.active(True)
>>> sta_if.scan()
>>> sta_if.connect("my_ap", "my_password")
    

MicroPython Sockets

>>> import socket
>>> sock = socket.socket(socket.AF_INET)
>>> sock.bind(('0.0.0.0', 80))
>>> sock.listen(5)
>>> sock.accept()
(<socket state=2 timeout=-1 incoming=0 off=0>, ('10.107.1.4', 37464))

Python Files

• Frozen in the firmware ...
  • micropython/esp8266/modules/: precompiled and then frozen into the firmware
  • micropython/esp8266/scripts/: frozen into the firmware as python source
• ... or copied in later to the internal VFAT FS
  • WebRepl: copy files through the webrepl interface
  • mpy-utils: copy files through the serial port REPL
    github: nickzoic/mpy-utils

Micropip

$ (cd unix; make axtls; make)
$ unix/micropython -m upip install \
    -p esp8266/modules micropython-functools

github: micropython/micropython-lib

What doesn't MicroPython have?

• An operating system
• Multiprocessing
• Much memory to play with
• Debugger / Profiler

My Projects ...

• Nicer WebREPL ... WebPAD
• mDNS
• Flobot

Summary

If you're interested in Microcontrollers / IoT / Robotics:

• ESP8266 is about the cheapest
• MicroPython is about the easiest

Hands On Workshop ...

Questions / Comments

Nick Moore
Mnemote Pty Ltd

• nick@mnemote.com
• http://mnemote.com/
• @mnemote

Slides:

• http://nick.zoic.org/buzzconf3/

Content and images © Mnemote Pty Ltd except where otherwise noted