Add flash/upload instructions, sample firmware image, and nodemcu-uploader

[submodule "ext/nodemcu-uploader"]

	path = ext/nodemcu-uploader

	url = https://github.com/kmpm/nodemcu-uploader.git

Most practical applications (such as the example in init.lua) also need the

following modules.

* hdc1080

* gpio

* hdc1080

* http

* mqtt

* node

* tmr

Readings will be published as `ccs811[influx_attr] eco2_ppm=%d,tvoc_ppb=%d,status=%d,error=%d`.

Unless `influx_attr = ''`, it must start with a comma, e.g. `influx_attr = ',device=' .. device_id`.

## Flashing

This repository contains a NodeMCU build that provides the required modules.

You can flash it using e.g. esptool:

```bash

esptool write_flash 0x00000 firmware/nodemcu-release-12-modules-2024-01-18-19-25-08-float.bin

```

This is required just once; changes to Lua files generally do not mandate

flashing a new NodeMCU image.

After flashing, the firmware will need a few seconds to initialize the

filesystem. You can then upload the Python code, e.g. using nodemcu-uploader:

```bash

ext/nodemcu-uploader/nodemcu-uploader.py upload *.lua

```

Afterwards, you can check whether everything works using the serial connection,

e.g.

```bash

pyserial-miniterm --dtr 0 --rts 0 /dev/ttyUSB0 115200

```

You may need to adjust the `/dev/tty` device name.

## Images

![](https://finalrewind.org/projects/esp8266-nodemcu-ccs811/media/hass.png)

Subproject commit 6178f40fff2deadd56b5bc474f9b4475ef444b37