LED Clock, Part III: Alexa?

Whilst I await delivery of more WS2812 LEDs, I wanted to start investigating how I can leverage the Alexa Gadget Toolkit integration, so that when I set a timer using Alexa, my LED clock can show the countdown.

Amazon make an Echo Wall Clock which does just that.

I found an open source project called nixie-timer, which had an Alexa Integration and was written for the ESP32

After a few hours of digging around, I had a very basic idea of what the code was doing. I started by trying to replicate the flow using the OOB ESP-IDF.

After many, many, many hours, I realised that I really didn’t know what I was doing, so I went back to the nixie-timer code and added the btstack ESP32 port into my code. This meant I could at least follow the samples provided.

I began trying to run some code myself, but the Bluetooth radio wouldn’t even start. I then took one of the BTStack examples and used that as a starting point. At least they worked.

After more hours, I got the code running, with the occasional kernel panic as I figured stuff out..

Eventually, I got it responding to the Alexa queries and receiving the messages for wakeword, timeinfo and timer.

Exactly what I wanted to achieve. I’m not 100% sure I know what’s going on, but I’ll get more understanding over time.

For starters, I want to use timeinfo to set the internal clock and then I want to use the timer command to display the countdown of an alexa timer.

Now that I’ve moved back to ESP-IDF, I’m going to have to bin my existing Arduino code which powers the LED strip and look at how to make that work.

Happy with progress.

My other WS2812 strip arrived the other day, so I’ve got to look at cutting and connecting the two strips to form one long 180 LED strip. Then I get get a feel of the overall diameter and cut some MDF to house the damn thing.

LED Clock, Update!

I managed to rework the time calculation and hour hand movement!

The clock is ticking!

I removed the RTC component and just let the loop run, with simple counters to simulate the passage of second, minutes and hours.

I think the transition of the “hands” needs to be smoother, more analogue. I’ll have to investigate if FastLED can do this.

LED Clock, Part II: Tick, Tock

In Part I, I covered the basics of controlling the LEDs. This covered the hands of the clock.

The second part of my investigation covers time and how to make the clock tick. The ESP 8266 I am using for this prototyping work doesn’t include a Real Time Clock, so I was required to add an external one.

Connecting the RTC module to my Wemos D1

With the module connected, I turned to the code. I’m using Arduino for this as it’s easy to prototype and there are lots of libraries!

#include <Wire.h>      //I2C library
#include <RtcDS3231.h> //RTC library

Setup is achieved in a couple of steps. To get me started, I just set the time.

RtcDS3231<TwoWire> rtcObject(Wire);

void setup()
{
  Serial.begin(9600);

  rtcObject.Begin();

  RtcDateTime currentTime = RtcDateTime(20, 04, 22, 0, 0, 0);

  rtcObject.SetDateTime(currentTime);
}

This starts the clock. In reality, as the module I’m using is battery backed, this step should only be performed once, but I found that having a fixed “time” would make debugging the lights a little easier.

I plan to revisit this code to ensure that I grab the current time from the internet when required.

Using the time is achieved by reading it.

void loop()
{
  Serial.println("Loop()");

 //get the time from the RTC
  RtcDateTime currentTime = rtcObject.GetDateTime();

  char str[20]; //declare a string as an array of chars

  //print the time for debugging.
  sprintf(str, "%d/%d/%d %d:%d:%d", 
          currentTime.Year(),       //get year method
          currentTime.Month(),      //get month method
          currentTime.Day(),        //get day method
          currentTime.Hour(),       //get hour method
          currentTime.Minute(),     //get minute method
          currentTime.Second()      //get second method
  );

Each part of the time is available in a named method, so to get an idea of where my LEDs should be, I grabbed the hour, minute and second.

// Fetch the current time
//
hour = currentTime.Hour();
minute = currentTime.Minute() * 2;
second = currentTime.Second() * 2;

I multiply them as I’m using a strip with 120 LEDs on it.

Building on my LED control code, I make the clock tick by turning off LEDs in the right place.

fill_solid(leds, NUM_LEDS, CRGB::DarkGreen);

// Fetch the current time
//
hour = currentTime.Hour();
minute = currentTime.Minute() * 2;
second = currentTime.Second() * 2;

// Hour
leds[hour - 1] = CRGB::Black;
leds[hour] = CRGB::Black;
leds[hour + 1] = CRGB::Black; 
leds[hour + 2] = CRGB::Black;
  
// Minute
leds[minute] = CRGB::Black;
leds[minute + 1] = CRGB::Black;

// Seconds
//
leds[second] = CRGB::Black;
leds[second + 1] = CRGB::Black;

FastLED.show();

I use multiple lights to make it more visible. With it now ticking, I hastily assembled the LED strip into a circle using cardboard and sellotape. I ran a length of alarm cable from the strip to the breadboard. To see it in action, I sellotaped it to the wall!

After letting it run for quite a while, I was surprised the hour “hand” hadn’t moved. It took my wife to point out that there aren’t 60 hours on a clock face 🤣

I’m pleased with these initial results.

As for my next steps, I’m not 100% sure. I’ve got to refine the “hands” code. I also need to think about how to mount it on the wall. I suspect it won’t be self contained and I’ll probably have a control box somewhere.

I’ve ordered another strip from the excellent Pimoroni and this will, I hope, let me add another 36 LEDs to the strip, taking it up to 180, which I think will give me a nice resolution.

I’ve got to think about power too. My estimate is that I’ll need around 3.5A to power the whole affair.

Expect another blog post soon!

LED Clock, Part I: Hands

The first part of making an LED clock was actually learning how to control the LEDs in the strip.

I had experimented with the LED strip before, flashing a rainbow, before realising I had no practical use the damn thing. At the time, I had used a Neopixel library.

Upon googling the subject again, another library came recommended, called FastLED. I had a quick look at the library and decided to give it a go.

#include <Arduino.h>
#include <FastLED.h>

#define NUM_LEDS 144

CRGB leds[NUM_LEDS];

void setup()
{
  Serial.begin(9600);

  FastLED.addLeds<NEOPIXEL, D4>(leds, NUM_LEDS);

  fill_solid(leds, NUM_LEDS, CRGB::Black);
}

void loop()
{
  leds[0].red   = 255;

  leds[1].green   = 255;

  leds[2].blue   = 255;

  leds[3] = CRGB::White;

  FastLED.show();
}
Four LEDs lit with different colours

Flashing an LED was just a case of turning it “black” and blue.

#include <Arduino.h>
#include <FastLED.h>

#define NUM_LEDS 60
CRGB leds[NUM_LEDS];

void setup() 
{ 
  Serial.begin(9600);
  FastLED.addLeds<NEOPIXEL, D2>(leds, NUM_LEDS); 
}

void loop() 
{
  Serial.write("On");

  leds[1] = CRGB::White; 
  FastLED.show(); 
  delay(30);
	
  Serial.write("Off");

  leds[1] = CRGB::Black; 
  FastLED.show(); 
  delay(30);
}
Flashing between white and “black”

I experimented a little more and ended up with a moving yellow light and a pretty static red slash of colour. This was sort of how I imagined the clocking running.

Power consumption was also on my mind. I had read that the each WS2812 on the strip would consume around 80mA. With my intention to power 180 of these, the power requirement was around 12A. This seemed very excessive, especially given the puny wires that were soldered to the strip. If somebody had tried to light them with that power consumption, the wire would have evaporated.

With my initial experimentations, a year before, I was sure I had run a LED rainbow lighting program through it and I new my 3A supply did the job and nothing went on fire.

I hooked it all up and lit all 144 LEDs.

It was only consuming 2.7A, including 200mA required to run the ESP8266 that was controlling it. I knew I’d need another 0.7A to power the intended 180 LEDs. This put the consumption at a little under 20mA for each WS2812.

With the LEDs under control, my next area of investigation was Real Time Clocks. I’ll do a post about that, once I’ve got something to report!

Lockdown LED Clock

A year or two ago, I picked up a WS2812B LED strip, but, for the life of me, could never think of anything useful to do with it.

Recently, however, I came across these LED powered clocks.

This feels like a project that will combine a few things:

  • ESP MCU
  • Real Time Clock
  • WS2812B strip
  • Maybe some Alexa integration?

Since I’m working from home for the duration, due to COVID-19, I get to recoup my usual commute time and put it towards something.

My starting point will be hooking up the strip to an ESP32 and trying to light one of the LEDs. I plan on a series of posts as I work towards my own clock!

Part I – https://tomasmcguinness.com/2020/04/14/led-clock-part-i-the-leds/

Part II – https://tomasmcguinness.com/2020/04/25/led-clock-part-ii-tick-tock/

Do we have any hot water?

A common occurrence in our house is bath time.

Another common occurrence is not having enough water for afore mentioned bath.

Our hot water is provided by a system boiler/unvented cylinder arrangement and I use a Nest to control the hot water (more on that later). The current schedule has it running the boiler for thirty minutes each day.

What is very annoying is that on some bath days we have ample hot water and on others, we don’t. We end up boiling the kettle to make up the difference. I don’t like the idea of just turning on the hot water as we might just be heating water that is already hot enough.

How much hot water do we have?

The first thing to figure out is how much how water we actually have. As I’ve mentioned, one some days we have ample and on other days we run out. Why does this happen?

Here are a few of the main factors that spring to mind:

  • The duration of the showers in the morning.
  • The ambient temperature in the loft.
  • How much washing up we’ve done.

The image above shows the basic operation of an unvented cylinder. Cold water enters the tank at the bottom and hot water exits at the top. The coil inside the tank is connected to the boiler and is responsible for actually heating the water in the tank. The whole thing works off the principal that the hot water will sit on top of the cold water and be pushed out the top.

My plan, therefore, was to attach temperature probes to the cold water entry and hot water exit and see what I could measure.

I was also interested in trying to measure the effect of the loft temperature on heat loss.

The Sensor

With my requirement of three sensors, I set about building a circuit that included an ESP-8266 and three DS18B20 temperature probes.

The DS18B20 uses something called the OneWire protocol, which means you can connect multiple sensors in parallel and use a single GPIO to read all the values. I found an excellent tutorial on the subject here – https://lastminuteengineers.com/multiple-ds18b20-arduino-tutorial/

With the long DS18B20 probes attached
The three temperature probes connected to the D1

For power, I wanted to use an off the shelf power supply. As these are mostly 5v, I added an LV1117V33 LDO. This little device accepts up to 7v input and outputs 3.3v, which was perfect to power the D1 and the sensors. To this, I connected a barrel input.

Powering the device with a 5v power supply

Software

I had originally planning on writing my own software to read the values from the sensors and send via MQTT to my HA instance. I actually did write my own software and even got the auto-discovery working, but as I wanted a web UI running on the device, so I could change easily change WiFi and MQTT settings, going down the custom road made little sense.

I was vagly aware that the excellent Tasmota Firmware (which I use in lots of smart sockets) did have some form of sensor support, so I did some reading. It turns out that not only did it support the DS18B20 sensor, it supported multiple ones 🙂

I flashed it onto the D1 mini and, after setup, navigated to the Configuration page.

You can select Module type as Generic (18) to gain access to the various GPIO pins on the device. I had connected the data wire of my sensors to D4, which is GPIO2. I choose teh DS18x20 option.

Setting up GPIO2 to handle the temp sensors

Once I hit save, the device rebooted and, lo and behold, the temperature started flowing into the UI!

Housing

Knowing how dusty my attic can be, I wanted to house the electronics in something, just to keep it clean and tidy. I had some Hammond enclosures (https://www.hammfg.com/electronics/small-case) and one of them seemed perfect.

I drilled four holes. One for each of the temperature probes and one for the power connector. The probes are held by three IP68 glands. Not necessary at all, but I just had them and thought they’d suit.

All the holes drilled and the sensor glands added
Circuit board installed
Lid on.

Once I had it all assembled, I plugged it in. It was at this point I wished I had some sort of indicator light to tell me it was powered or connected to the internet. I had to wait a minute, but eventually the Tasmota appeared on my list of connected clients.

Installation

I have a pretty standard unvented cylinder. There are two pipes entering at the bottom, the cold water inlet and the hot water return to the boiler. The hot water outlet is at the top.

My hot water tank in all its glory!
I stuffed one of the probes under the lagging at the top
The cold water inlet at the back – It isn’t even fully lagged!
I stuff another probe up against the cold water.

The third probe I just left hanging in the air, supported by a piece of furniture. My loft really is full of junk!

The data

The reading from the probes

From the three probes, I could have a guess as to which probe was were!

The 15.8 was the ambient temperature in the loft, with the 19 and 48 degree measures pointing to the inline and outlets.

Measures taken first thing in the morning

My hot water turns on for 30 minutes each morning (30 mins because the Nest Thermostat won’t let me do anything shorter). I looked at the temperatures when I got up around 7am and I could see the top temp was at almost 60 degrees.

Next Steps

I’m going to let this setup run for a few weeks and note the days we run low/out of hot water.

Combined with better control of my hot water (I’m thinking of replacing my Nest’s control), I think there is an opportunity to reduce the time my hot water needs to actually be turned on.

Other things might be possible, such as extra hot water when we have guests over (using their connection to the house WiFi as an indicator of presence). Or ensuring these is hot water for washing the dishes at 6pm each night.

I’ll post an update, once I’ve got some findings!

Update 24th Feb

With the sensor installed for over a week, I pulled a graph from Home Assistant.

A week’s worth of readings

The green line, which reaches the highest values is the outlet temperature. You can see the rather pronounced peaks and troughs. The orange line represents the inlet temp and that does spike a little, each morning, when the heating is turned on. The red line is the ambient temp of the loft. It does vary by a few degrees.

From the graph, it’s very obvious when we’re very low on hot water!

I also find the temperature loss over the course of the day to be interesting. This is obviously a function of the ambient temperature in the loft, but also, I suppose, of the temperature of the incoming water.

I’m in the process of upgrading my Home Assistant instance and I hope to be able to retain more data than I can do right now. I’d like to be able to compare summer months to winter months, so I need a few months of stored data to perform that comparison.

More to come!

Shelly 1 Relay

With Den Automation facing immanent demise, I’ve been looking at alternatives.

I came across the Shelly 1 relay, quite by accident, whilst looking at some Sonoff stuff. It immediately piqued my interest, mostly because it taught me that I didn’t know anything about lighting circuits in the UK.

I’ve installed my fair share of lighting fixtures during the rennovation of my home and whilst I was astonished at the number of connections in a ceiling rose, I never really took any time to investigate why.

Image result for ceiling rose wiring
Typical ceiling rose wiring arrangement in UK home

I had made my own attempts at automating lighting when I first moved in. This was a crude affair, which involved putting a Sonoff Basic relay in between the rose and bulb.

Whilst functional, the downside was that flipping the physical switch turned the relay off. Bye, bye, remote switching.

This is where the Shelly 1 comes into play.

Shelly 1 Wi-Fi WLAN switching actuator 16 A SHELLY SHELLY 1
The Shelly 1 relay. Small, but powerful 🙂

I came across an excellent post, which explained how to connect the little unit to a UK ceiling rose, which is well worth checking out – https://gist.github.com/lordneon/aecf24035a4dc5e6b950977e37aeb930

Essentially, the Shelly 1 is connected to the permanent supply, so it’s always on, regardless of the physical switch. The Shelly is also connected to the physical switch, so it knows when it’s been flipped.

This means that the light can be turned on and off via an API *and* by the existing light switch! I immediately ordered some.

A Christmas tree of relays.

My order included two Sonoff Minis, but I choose the Shelly1 to begin with as it supports MQTT control out of the box (which bypasses the Shelly Cloud – local control all the way). I know the Minis have to be flashed with Tasmota firmware to support MQTT and I didn’t want to get distracted!

Installation

WARNING! Please don’t attempt anything related to mains electricity unless your confident in your ability. Always remember to isolate circuits from the fuse board before doing anything!! I am not responsible if anything happens.

Installation was very straight forward with the help of the excellent WAGO connectors. Following the diagram, I installed the Shelly 1.

Wiring Diagram
https://gist.github.com/lordneon/aecf24035a4dc5e6b950977e37aeb930
The Shelly 1 wired in!

Once I’d restored power from the fuse board, I went through the configuration process. This followed the standard pattern of connecting to the Shelly’s WiFi network, connecting to my own WiFi network and then entering the MQTT server address and credentials.

It worked first time!

I set it’s Switched Live mode to edge, so that means that any change in the physical switch will turn it on or off, perfect for my needs.

Adding the Shelly to my Home Assistant required the addition of an MQTT entity with the appropriate topics.

  - platform: mqtt
    name: "Shelly-1"
    state_topic: "shellies/shelly1-B8B728/relay/0"
    command_topic: "shellies/shelly1-B8B728/relay/0/command"
    payload_on: "on"
    payload_off: "off"   

I repeated the process on another light in my house.

This was installed into a standard plastic ceiling rose, but unfortunately the cover wouldn’t close due to the thickness of the Shelly.

As this is pretty unsightly, I’ve decided to find a nice ceiling rose with the space to hold the Shelly before I install any more.

I’m so happy with these, they are a perfect replacement for my defunct Den switches. I’ll be replacing all of Den’s switches with these Shelly 1s once I find a good rose.