Build your own IoT/MQTT node for less than $2 | Hacker News Reader

Build your own IoT/MQTT node for less than $2

albert-david.blogspot.com

198 pointsalbert007_d40 comments

For those new to this, you can get little esp8266 based modules with usb, header pins etc for about the same price. https://en.m.wikipedia.org/wiki/NodeMCU

Arduino software compatible too.

Those are really cool. Here's an esp8266 framework primarily intended for home automation: https://github.com/xoseperez/espurna

I use this in about ten devices (one of which is a custom-built dog feeder) and love it. I hate using closed-source IoT devices and this is a perfect alternative.

custom-built dog feeder

You better not hook up to the amplifier. There's a slight possibility for overload.

https://www.youtube.com/watch?v=WjX1jU9pQeY

Please do tell more! Is there a blog?

My site is at https://www.stavros.io/ and various smaller projects at https://www.makerfol.io/stavros/. The particular dog feeder is mostly my dad's build, I only provided the software and relays to trigger it, so it's not written up anywhere. I can post some photos if you like.

I would go with the Lolin D1 mini, it's better designed and has a more convenient form factor, in my opinion.

Having worked with a ton of ESP8266 variants, I agree with this. (The D1 Mini Pro has more RAM and is great.)

The ESP32 is good out of the box, and can be even better if you need dual core or Bluetooth.

> Arduino software compatible too.

The Moddable JavaScript (ES2017) runtime[1] works great on ESP8266 and ESP32 microcontrollers as well.

[1] https://github.com/Moddable-OpenSource/moddable

It's cheap but what's the 0power consumption? This tutorial from Eric Tsai covers a similar architecture but a lot more extensible, with a lot more explanation, and each end node can be powered from a coin cell for many years:

https://www.hackster.io/erictsai/lora-tooth-small-ble-sensor...

ESP-12f module running with tasmota firmware consumes around 30mA when measured on the 5V side, if you want to go further down, deep-sleep option of ESP8266 is the way to go, but tasmota firmware doesnt support deep-sleep(may be you need node-mcu firmware to achieve sub-mA consumption). There are CR-123 3v battery powered ESP8266 temperature/humidity products which use deep-sleep mode and report the sensor samples every hour so that devices operates atleast a year on battery power(check out shelly H&T product)

That was a very useful article. Thank you for the link.

I recently found out about Sonoff-Tasmota ( https://github.com/arendst/Sonoff-Tasmota ), i hate it. Because now i bought for 300 € of Sonoff products for home-automation based on the MQTT protocol.

(The project allows you to flash the Sonoff products with custom firmware)

They also have an IR module, for customizing your remote.

Anyone else has other ideas that are similar for home automation without adjusting your electronic wiring?

Like you hinted, flashing Sonoff-Tasmota firmware on ESP8266 hardware lets you get A LOT of home automation equipment for fairly little. They make many devices and someone getting started should checkout the Sonoff-Tasmota for supported devices AND check out Sonoff.

If you don't want to use a Sonoff Basic or maybe the bigger 4 channel option, I'd suggest getting some of their wall adapters like the S31 (think Wemo wall plug). There is a confirmed flash for Sonoff-Tasmota & ESPurna for it and would let someone dip their toes into cheap home automation with MQTT.

Yeah, but on the plus side, if you were buying "polished" products, 300 € would get you a hub and two lightbulbs...

Is there an hobby equivalent for Bluetooth Low Energy (BLE)? Wifi tends to be power hungry for battery-operated devices. With BLE, you can get months of lifespan while still being able to connect to it with your phone.

I was looking at the micro:bit, but it's still $15. Anything in the $2 range for BLE?

Try the ESP32, it might fit the bill, although I've never worked with its Bluetooth capabilities and don't know much about them.

I've experimented with those ESP32 chips from a few sources on a handful of boards (lots of cheapo knockoffs floating around) and haven't been happy with the performance or reliability of any of them for BLE. So far Nordic nRF52 holds the lead in my experience (they do cost a bit more though).

Nordic is good, but STM32 is also affordable and quite decent.

There are some cheap nRF51822 modules from China which come close to that price range. You might even be able to get them working with the open source Apache Mynewt stack, though I never got around to trying.

I wouldn't use an esp32 if your concern is power consumption, as they tend to be pretty power hungry, even when they're only doing BLE. The Nordic nRF52 series is pretty good, and you can find shielded modules for around $10-15 in single unit quantities.

$2 is a bit of a stretch... You can probably get the bare IC for ~$5 if you're willing to do the antenna yourself.

It sounds like you're after closer-range than this is intended for, and I've no idea on relative power consumption - but you may want to check out LoRa [1]. More Zigbee-alike than BT(LE)-alike.

[1] https://en.wikipedia.org/wiki/LoRa

ESP32 does BLE

Can someone ELI5 what can be accomplished with these devices?

I am not familiar with them, and the build looks simple - but what do once created? Is it simply a BLE beacon?

Cheap boards like the ESP-12F (ESP8266) allow you to remotely control a device or receive sensor data, like that from a DHT11 temperature-humidity sensor. Instead of paying a lot of money, you can flash your own firmware on a device and make your own custom IoT device.

MQTT is a messaging protocol used to communicate with the device. You can use something like Mosquitto to communicate with your new IoT device. It is lightweight protocol and easy to work with.

You'd use something like an ESP32 – which has Bluetooth – if you want a simple BLE beacon, otherwise if you don't need Bluetooth then an ESP8266 device would likely work better.; If you want to look at related videos, I'd suggest looking at the YouTube channel Andreas Spiess publishes with various devices. He has a few videos on BLE and ESP32 (ex: https://www.youtube.com/watch?v=KNoFdKgvskU) where he goes into detail.

On the one side, you have WiFi and therefore can communicate with servers using different protocols. On the other side, you have spi, i2c and gpio, to talk to sensors, blink LEDs, move motors.

It's a real-world-to-web interface.

The ESP8266 is wifi. The slightly more expensive ESP32 adds Bluetooth and some extra features. You can use them to run mini web server, MQTT, etc. Think of them like a supercharged Arduino with connectivity built in.

Ahh - so coupled with whatever sensor you have, you can have a wifi broadcast capability at extreme low cost...

So, ostensibly - if you have these all participate in an SSID of e.g. "sensors", then you can place these all over and have a low-cost mechanism to deliver the reads to your (already) existing wifi infra...

So the key, then, is the family of sensor types you want to place on them. The limitations in the case of this object are power and size....

So given that - whats the minimum size battery req'd to run this little guy?

Then What is the power req of the sensors you attach -- then whats the lifespan of that power budget and then servicability to replace it?

I like this... a lot.

I have a bunch of BLE sensor beacons from china which cost ~8 but they are dumb as rocks.

This provides a heck of a lot more functionality than those...

Unless there are gotcha's which I am naive to?

Battery depends more on what you are doing.

Most boards and sensors use either 5 or 3.3 volts DC.

You can put the device in a sleep or hibernate mode and have it only connect to wifi periodically or when triggered.

Also, using encryption, like WPA2 increases battery use.

The esp8266 module itself runs at 3.3V but seems happy with a couple of AA batteries. Tried with CR3032 but it can't deliver enough current. After all, it is doing WiFi.

Google ‘joule thief’.

This is interesting. What chip do ESP12F's have for USB?

I did a quick search and nothing came up. Most ESP8266 projects refer to the node mcu board rather than the module. Those boards usually have a USB <-> serial chip.

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