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Add blog post for ESP8266 and MicroPython
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‎source/_posts/2016-07-21-esp8266-and-micropython-part1.markdown

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---
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layout: post
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title: "ESP8266 and MicroPython - Part 1"
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description: "Using MicroPython on ESP8266 based devices and Home Assistant."
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date: 2016-07-21 06:00:00 +0200
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date_formatted: "July 21, 2016"
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author: Fabian Affolter
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comments: true
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categories: How-To
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og_image: /images/blog/2016-07-micropython/social.png
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---
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<img src='/images/blog/2016-07-micropython/micropython.png' style='clear: right; border:none; box-shadow: none; float: right; margin-bottom: 12px;' width='200' />
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The first release of Micropython for ESP8266 was delivered a couple of weeks ago. The [documentation](http://docs.micropython.org/en/latest/esp8266/esp8266_contents.html) covers a lot of ground. This post is providing only a little summary which should get you started.
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If you don't participated in the KickStarter campaign only the source code was available. This meant that you needed to build the firmware on your own. As of now the [pre-built firmware](https://micropython.org/download/#esp8266) is available for the public.
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<!--more-->
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The easiest way is to use [esptool.py](https://github.com/themadinventor/esptool) for firmware handling tasks. First erase the flash:
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```bash
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$ sudo python esptool.py --port /dev/ttyUSB0 erase_flash
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esptool.py v1.0.2-dev
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Connecting...
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Erasing flash (this may take a while)...
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```
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and then load the firmware. You may adjust the file name of the firmware binary.
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```bash
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$ sudo python esptool.py --port /dev/ttyUSB0 --baud 460800 write_flash --flash_size=8m 0 esp8266-2016-07-10-v1.8.2.bin
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esptool.py v1.2-dev
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Connecting...
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Running Cesanta flasher stub...
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Flash params set to 0x0020
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Writing 540672 @ 0x0... 540672 (100 %)
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Wrote 540672 bytes at 0x0 in 13.1 seconds (330.8 kbit/s)...
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Leaving...
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```
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Now reset the device. You should then be able to use a terminal program like `minicom` or `picocom` to connect and get the [REPL (Read Evaluate Print Loop)](http://docs.micropython.org/en/latest/esp8266/esp8266/tutorial/repl.html#getting-a-micropython-repl-prompt) prompt.
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```bash
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$ sudo minicom -D /dev/ttyUSB0
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#4 ets_task(4020e374, 29, 3fff70e8, 10)
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WebREPL daemon started on ws://192.168.4.1:8266
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Started webrepl in setup mode
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could not open file 'main.py' for reading
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#5 ets_task(4010035c, 3, 3fff6360, 4)
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MicroPython v1.8.2-9-g805c2b9 on 2016-07-10; ESP module with ESP8266
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Type "help()" for more information.
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>>>
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```
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<p class='note'>
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The public build of the firmware may be different than the firmware distributed to the backers of the campaign. Especially in regard of the [available modules](http://docs.micropython.org/en/latest/esp8266/py-modindex.html), turned on debug messages, and alike. Also, the WebREPL may not be started by default.
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</p>
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Connect a LED to pin 5 (or another pin of your choosing) to check if the ESP8266 is working as expected.
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```python
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>>> import machine
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>>> pin = machine.Pin(5, machine.Pin.OUT)
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>>> pin.high()
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```
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You can toogle the LED by changing its state with `pin.high()` and `pin.low()`.
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Various ESP8266 development board are shipped with an onboard photocell or a light dependent resistors (LDR) connected to the analog pin of your ESP8266 check if you are able to obtain a value.
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```python
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>>> import machine
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>>> brightness = machine.ADC(0)
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>>> brightness.read()
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```
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The REPL can also be accessed through with a browser. For your convinience, is an instance of the WebREPL client hosted at [http://micropython.org/webrepl](http://micropython.org/webrepl). Alternatively, you can create a local clone of their [GitHub repository](https://github.com/micropython/webrepl). This is neccessary if your want to use the command-line tool `webrepl_cli.py`.
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Make sure that you are familiar with REPL and WebREPL because this will be needed soon. Keep in mind the password for the WebREPL access.
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Read the [instructions](http://docs.micropython.org/en/latest/esp8266/esp8266/tutorial/network_basics.html) about how to setup your wireless connection. Basically you need to upload a `boot.py` file to the microcontroller and this file is taking care of the connection setup. Below you find a sample which is more or less the same as shown in the [documentation](http://docs.micropython.org/en/latest/esp8266/esp8266/tutorial/network_basics.html#configuration-of-the-wifi).
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```python
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def do_connect():
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import network
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SSID = 'SSID'
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PASSWORD = 'PASSWORD'
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sta_if = network.WLAN(network.STA_IF)
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ap_if = network.WLAN(network.AP_IF)
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if ap_if.active():
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ap_if.active(False)
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if not sta_if.isconnected():
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print('connecting to network...')
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sta_if.active(True)
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sta_if.connect(SSID, PASSWORD)
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while not sta_if.isconnected():
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pass
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print('Network configuration:', sta_if.ifconfig())
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```
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Upload this file:
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```bash
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$ python webrepl_cli.py boot.py 192.168.4.1:/boot.py
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```
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If you reboot, you should see your current IP address in the terminal.
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```bash
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>>> Network configuration: ('192.168.0.10', '255.255.255.0', '192.168.0.1', '192.168.0.1')
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```
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First let's create a little consumer for Home Assistant sensor's state. The code to place in `main.py` is a mixture of code from above and the [RESTful API](/developers/rest_api/) of Home Assistant. If the temperature in the kitchen is higher than 20 °C then the LED connected to pin 5 is switched on.
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<p class='note'>
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If a module is missing then you need to download is it from [MicroPython Library overview](https://github.com/micropython/micropython-lib) and upload it to the ESP8266 with `webrepl_cli.py` manually.
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</p>
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```python
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# Sample code to request the state of a Home Assistant entity.
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API_PASSWORD = 'YOUR_PASSWORD'
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URL = 'http://10.100.0.197:8123/api/states/'
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ENTITY = 'sensor.kitchen_temperature'
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TIMEOUT = 30
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PIN = 5
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def get_data():
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import urequests
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url = '{}{}'.format(URL, ENTITY)
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headers = {'x-ha-access': API_PASSWORD,
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'content-type': 'application/json'}
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resp = urequests.get(URL, headers=headers)
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return resp.json()['state']
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def main():
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import machine
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import time
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pin = machine.Pin(PIN, machine.Pin.OUT)
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while True:
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try:
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if int(get_data()) >= 20:
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pin.high()
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else:
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pin.low()
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except TypeError:
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pass
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time.sleep(TIMEOUT)
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if __name__ == '__main__':
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print('Get the state of {}'.format(ENTITY))
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main()
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```
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Upload `main.py` the same way as `boot.py`. After a reboot (`>>> import machine` and `>>> machine.reboot()`) or power-cycling your physical notifier is ready.
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If you run into trouble, press "Ctrl+c" in the REPL to stop the execution of the code, enter `>>> import webrepl` and `>>> webrepl.start()`, and upload your fixed file.
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‎source/images/blog/2016-07-micropython/micropython.png

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