195 lines
9.0 KiB
ReStructuredText
195 lines
9.0 KiB
ReStructuredText
.. _intro:
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Getting started with MicroPython on the ESP8266
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===============================================
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Using MicroPython is a great way to get the most of your ESP8266 board. And
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vice versa, the ESP8266 chip is a great platform for using MicroPython. This
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tutorial will guide you through setting up MicroPython, getting a prompt, using
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WebREPL, connecting to the network and communicating with the Internet, using
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the hardware peripherals, and controlling some external components.
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Let's get started!
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Requirements
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------------
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The first thing you need is a board with an ESP8266 chip. The MicroPython
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software supports the ESP8266 chip itself and any board should work. The main
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characteristic of a board is how much flash it has, how the GPIO pins are
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connected to the outside world, and whether it includes a built-in USB-serial
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convertor to make the UART available to your PC.
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The minimum requirement for flash size is 1Mbyte. There is also a special
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build for boards with 512KB, but it is highly limited comparing to the
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normal build: there is no support for filesystem, and thus features which
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depend on it won't work (WebREPL, upip, etc.). As such, 512KB build will
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be more interesting for users who build from source and fine-tune parameters
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for their particular application.
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Names of pins will be given in this tutorial using the chip names (eg GPIO0)
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and it should be straightforward to find which pin this corresponds to on your
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particular board.
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Powering the board
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------------------
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If your board has a USB connector on it then most likely it is powered through
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this when connected to your PC. Otherwise you will need to power it directly.
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Please refer to the documentation for your board for further details.
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Getting the firmware
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--------------------
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The first thing you need to do is download the most recent MicroPython firmware
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.bin file to load onto your ESP8266 device. You can download it from the
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`MicroPython downloads page <http://micropython.org/download#esp8266>`_.
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From here, you have 3 main choices
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* Stable firmware builds for 1024kb modules and above.
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* Daily firmware builds for 1024kb modules and above.
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* Daily firmware builds for 512kb modules.
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The best bet is nearly always to go for the Stable firmware builds.
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An exception to this though is if you have an ESP8266 module with only 512kb
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of onboard storage. You can easily tell by trying to load a Stable firmware
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build and if you get the error below, then you may have to use the Daily
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firmware builds for 512kb modules.
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WARNING: Unlikely to work as data goes beyond end of flash.
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Deploying the firmware
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----------------------
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Once you have the MicroPython firmware (compiled code), you need to load it onto
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your ESP8266 device. There are two main steps to do this: first you
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need to put your device in boot-loader mode, and second you need to copy across
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the firmware. The exact procedure for these steps is highly dependent on the
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particular board and you will need to refer to its documentation for details.
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If you have a board that has a USB connector, a USB-serial convertor, and has
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the DTR and RTS pins wired in a special way then deploying the firmware should
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be easy as all steps can be done automatically. Boards that have such features
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include the Adafruit Feather HUZZAH and NodeMCU boards.
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For best results it is recommended to first erase the entire flash of your
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device before putting on new MicroPython firmware.
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Currently we only support esptool.py to copy across the firmware. You can find
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this tool here: `<https://github.com/espressif/esptool/>`__, or install it
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using pip::
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pip install esptool
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Versions starting with 1.3 support both Python 2.7 and Python 3.4 (or newer).
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An older version (at least 1.2.1 is needed) works fine but will require Python
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2.7.
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Any other flashing program should work, so feel free to try them out or refer
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to the documentation for your board to see its recommendations.
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Using esptool.py you can erase the flash with the command::
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esptool.py --port /dev/ttyUSB0 erase_flash
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And then deploy the new firmware using::
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esptool.py --port /dev/ttyUSB0 --baud 460800 write_flash --flash_size=detect 0 esp8266-20170108-v1.8.7.bin
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You might need to change the "port" setting to something else relevant for your
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PC. You may also need to reduce the baudrate if you get errors when flashing
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(eg down to 115200). The filename of the firmware should also match the file
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that you have.
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For some boards with a particular FlashROM configuration (e.g. some variants of
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a NodeMCU board) you may need to use the following command to deploy
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the firmware (note the ``-fm dio`` option)::
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esptool.py --port /dev/ttyUSB0 --baud 460800 write_flash --flash_size=detect -fm dio 0 esp8266-20170108-v1.8.7.bin
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If the above commands run without error then MicroPython should be installed on
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your board!
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Serial prompt
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-------------
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Once you have the firmware on the device you can access the REPL (Python prompt)
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over UART0 (GPIO1=TX, GPIO3=RX), which might be connected to a USB-serial
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convertor, depending on your board. The baudrate is 115200. The next part of
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the tutorial will discuss the prompt in more detail.
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WiFi
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----
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After a fresh install and boot the device configures itself as a WiFi access
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point (AP) that you can connect to. The ESSID is of the form MicroPython-xxxxxx
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where the x's are replaced with part of the MAC address of your device (so will
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be the same everytime, and most likely different for all ESP8266 chips). The
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password for the WiFi is micropythoN (note the upper-case N). Its IP address
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will be 192.168.4.1 once you connect to its network. WiFi configuration will
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be discussed in more detail later in the tutorial.
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Troubleshooting installation problems
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-------------------------------------
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If you experience problems during flashing or with running firmware immediately
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after it, here are troubleshooting recommendations:
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* Be aware of and try to exclude hardware problems. There are 2 common problems:
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bad power source quality and worn-out/defective FlashROM. Speaking of power
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source, not just raw amperage is important, but also low ripple and noise/EMI
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in general. If you experience issues with self-made or wall-wart style power
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supply, try USB power from a computer. Unearthed power supplies are also known
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to cause problems as they source of increased EMI (electromagnetic interference)
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- at the very least, and may lead to electrical devices breakdown. So, you are
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advised to avoid using unearthed power connections when working with ESP8266
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and other boards. In regard to FlashROM hardware problems, there are independent
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(not related to MicroPython in any way) reports
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`(e.g.) <http://internetofhomethings.com/homethings/?p=538>`_
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that on some ESP8266 modules, FlashROM can be programmed as little as 20 times
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before programming errors occur. This is *much* less than 100,000 programming
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cycles cited for FlashROM chips of a type used with ESP8266 by reputable
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vendors, which points to either production rejects, or second-hand worn-out
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flash chips to be used on some (apparently cheap) modules/boards. You may want
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to use your best judgement about source, price, documentation, warranty,
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post-sales support for the modules/boards you purchase.
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* The flashing instructions above use flashing speed of 460800 baud, which is
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good compromise between speed and stability. However, depending on your
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module/board, USB-UART convertor, cables, host OS, etc., the above baud
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rate may be too high and lead to errors. Try a more common 115200 baud
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rate instead in such cases.
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* If lower baud rate didn't help, you may want to try older version of
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esptool.py, which had a different programming algorithm::
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pip install esptool==1.0.1
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This version doesn't support ``--flash_size=detect`` option, so you will
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need to specify FlashROM size explicitly (in megabits). It also requires
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Python 2.7, so you may need to use ``pip2`` instead of ``pip`` in the
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command above.
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* The ``--flash_size`` option in the commands above is mandatory. Omitting
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it will lead to a corrupted firmware.
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* To catch incorrect flash content (e.g. from a defective sector on a chip),
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add ``--verify`` switch to the commands above.
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* Additionally, you can check the firmware integrity from a MicroPython REPL
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prompt (assuming you were able to flash it and ``--verify`` option doesn't
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report errors)::
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import esp
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esp.check_fw()
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If the last output value is True, the firmware is OK. Otherwise, it's
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corrupted and need to be reflashed correctly.
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* If you experience any issues with another flashing application (not
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esptool.py), try esptool.py, it is a generally accepted flashing
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application in the ESP8266 community.
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* If you still experience problems with even flashing the firmware, please
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refer to esptool.py project page, https://github.com/espressif/esptool
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for additional documentation and bug tracker where you can report problems.
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* If you are able to flash firmware, but ``--verify`` option or
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``esp.check_fw()`` return errors even after multiple retries, you
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may have a defective FlashROM chip, as explained above.
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