Posted on by — Leave a comment

CUMonitor Consumer Release

Development of the CUMonitor hardware is progressing and the first boards acceptable for consumer release have arrives and are going thru soak testing.

CUMonitor PCB changes

The major changes have been to add the facility to power the board through a micro USB connector adding onboard voltage regulation of the 3.3v.  The new A to D circuits can run without the the addition of a burden resistor so these have been removed. This means that the CUMonitor consumer PCB assumes that the 30A 1V current clamps will be used. But this should be OK form most household use cases. The surface mount spaces for the burden resistor have been left in case 100A clamps are required. There was a missing resistor on the previous board that is also fixed.

Posted on by — Leave a comment

CU Monitor PCB Upgrades

The CU Monitor PCB upgrade has involved quite a few changes. Moving to the ESP32S2 processor has meant completely revamping  the build to use  the newer and faster processor. Aside from doing away with the with the ADS1115 chip and reading the A to D values across the I2C bus the board has simplified in a number of other ways.

I’m pleased with the upgrade process even though the PCB board will have to be recreated. The  porting meant using new libraries and did away with the I2C bus. There is lot more space on the chip for expansion and the number of samples  per second has risen to more than 9000 from the few hundreds we had with the old design. The current run of PCB’s have burden resistors that are now redundant and one missing resistor from channel 2. But otherwise appear to work great. I’m soak testing them now before ordering some production quality boards and to see if there are any “undocumented software features” in the new libraries.

One change to go in is adjusting the recess of the jack plug sockets these need to be less as when the jack plugs are inserted thru the case they experience an ejection force because the case pushes the jack plugs away from the PCB. Also I need to add pylon holes to allow rapid alignment when the PCB is inserted into the case

Posted on by — 2 Comments

A week of Gaming

Holiday in the Isle of Wight

A group of friends meet up in the idyllic setting that is a well converted barn in the rural wilds of  the Isle of Wight on the 24th October(already sounds like a Plot from the ICFTLLLS). Instead of roving picturesque countryside that surrounds us  we drag out of dusty bags and carryalls, pieces of paper and dice that have not  seen the light of day for a dozen years and start chattering about characters long not used. Generating new characters and starting to a prepare for the week ahead

Two games a planned for the first weekend with two others in the wings in case there should be a gap in the gaming. 

  • It came from the Late Late Late Night Movie Show
  • Golden Heroes
  • Space 1889
  • Melee,Magic and Maelstrom (my system) 

It came from the Late Late Late show (ICFTLLLS :Saturday)

Is a tongue in cheek role playing game set in the world of American B movies where players play vapid and silly characters through suspect plots with hilarious consequences.  Not at all serious this game resounds of with shouts of “Stunt Double !” as players try to muddle their way through a plot where cinematic treats such and red eyed zombies, EMP Bombs and cursed crystal skulls  try to eat,blow up or possess the characters

The scenario:  The players characters are  attending an audition for a Movie set in the grounds of Rochester Castle which also happens to be the site on an Archaeological  dig when a crystal skull is dug up by the Archaeologists! …. this explodes with an EMP blast  which beside being inadequately explained resulted in black out of Rochester! and most of the population of Rochester being converted into Red eyed Zombies. The characters are then pursued through the streets of Rochester by Zombies…… After a charge up and down the A2 in a double decker  bus the characters are pursued by supernatural forces and the movie climaxes with  the characters detonating the SS Richard Mongonery on Nore sandbank in the Thames estuary near Sheerness  to destroy  the  crystal Skull… A hugely cinematic ending to a days gaming.  

Golden heros

Never a sensible game we played a mixture of eclectic Superheros through a meandering set of encounters where the players failed to deal with two different alien races some mainly marital/martial super villains and failed to stop the end of the world plot that was only saved by one players misspelling of martial meaning they were a marital expert  rather than a Martial Arts expert and therefore could save the day. Far to little alcohol can be used as an excuse. 

Melee Magic and Maelstrom

The climax of the high level parties trip to hell culminated in the return of the high level  characters to the prime material plane only to find the BBEG laying in wait to ambush them  with a fight including dragons and spell jamming space ships bombarding evil nasties with cannon fire.  Suitably apocalyptic with my attempt to run two intersecting time lines where the away teams return from Hell was being intercepted by the BBEG and the characters left behind on the spell Jammer Charging in all guns blazing to rescue the beleaguered away team.

Space 1889

A game set in the Victorian era exposed the whole gamut of Victorian opinions, bigotries and inhibitions. The party, a mixture of minor nobility, anarchists , domestic staff and common tradesmen  foiled a Prussian plot to steal “secrets”  that would tilt the balance  of power. With cameo appearances from Nikola Tesla and Thomas Edison. The party followed the trail of breadcrumb clues down the Nile to a mysterious pyramid. 

Unamed

A system that still remains unnamed after more than 35 years of existence. A table top FRP game set in a bespoke medieval  fantasy world with magic and combat with 35 years of player lore and campaigning.  The players were tasked with finding out why NPCs were disappearing from a local community …. A classic and almost traditional trope for a fantasy setting. Resulting in a delve into local limestone caves populated by Bug Bears and Spider themed bad guys.

Nuclear Armageddon !!!

A number of table top board games were played through out the a week:

  • The game Warlord apparently “the Original game” that the Games Workshop game of the 1980-90s previously known to me as   Apocalypse was based on.
  • Nuclear war and Nuclear Proliferation

Bit of a Nuclear Armageddon theme I thought ! These games were played in a tongue in cheek Homage by those of us who grew up in the shadow of the mushroom  cloud and now are nearing retirement. Much to the confusion of the Younger generation players. 

The Little Barn, Dungewood lane, Shorwell IOW

 A great place to holiday with friendly and helpful management, Richard and Susan were fantastic hosts we heartily recommend this venue for your stay on the IOW. They coped very well with our group of eccentric table top game players. Thank you both we had a fabulous time

My only regret was that we didn’t make the  time to visit the stunning local scenery… Please pardon a bunch of philistines who don’t  meet up often enough for not taking advantage of your fantastic local sights. The sunrises thru the patio doors are Epic !

Posted on by — 13 Comments

GM Light

GM Light is an actual product now, rather than an idea in my head! I suppose I need to explain what it is and where it originated, well I have been a player of fantasy role playing games since I was at university in the 1980s initially as a player but very soon after, a GM. I have run many campaigns over the years and one thing that struck me was the sheer quantity of papers and paraphernalia that a GM ends up carrying to a game session. This is my attempt to reduce the amount of stuff you have to tote. Also you can bet if you roll a random encounter you won’t have the exact figure for the monster.

GM light is my solution. I have sourced 310 tokens of all the typical monsters and bad guys to allow a phys. rep. of the monster to be placed down. The numbers of the tokens lend themselves to creating a random encounter for most encounters. Rather than have a fold out battle mat which has issues with the creases and laying flat I have created two sided dry wipe tiles.

Because I wanted to cover as many role playing game systems as possible, I came up with the idea of the flavour pack. The full GM travel set comprises the GM Light core set and a flavour pack.

The flavour pack will have all the extras that are specific to a game system like monster stat cards,  a combat tracker, a GM screen and a spell template. This way generic monsters from myth, folklore and popular fiction can be reused with the flavour pack for each game system.

Possible flavour packs include :

  1. DnD 5th Edition
  2. Pathfinder 2nd Edition
  3. DnD 3.5
  4. Pathfinder
  5. Chivalry and Sorcery
  6. Runequest
  7.  Basic Fantasy RPG
  8. Warhammer Fantasy Roleplay 4E
  9. King Arthur Pendragon
  10.  Middle Earth Role Playing
  11. GURPS (Generic Universal RolePlaying System)
GM Light  core could support all of them (once the appetite for GM light Core is proven) but practically, before paying for the development of flavor packs for games that may no longer be played. I need find some way to identify which are still relevant. Comments on how to poll the community please !
 

The GM travel kit will provide most of the reference material and game mechanics required to run a fantasy role playing game in a handy pack,  significantly reducing the amount of materials required to run a session.

Posted on by — Leave a comment

Calculating the power

The CU monitor senses the current flow at the two points marked.  It’s important to realise that even if the voltage generated by the Grid tie inverter has exactly the same peak voltage as the National Grid the current draw into the house may vary throughout the waveform because the loads in the house are not perfectly resistive and the current consumption of devices in the house will not be linear with voltage. Practically, this may result in current flowing into the house at some parts of the waveform and out at others. This means that the current at the the solar panels and the Grid tie inverter input feed will have an ambiguity, adding a safe margin ensures that current flow in or out throughout the whole of the waveform can be accounted for.

The current will be in phase  with the voltage for a purely resistive load, will lead the voltage for a capacitive load and will trail for an inductive load. We need to measure the current at the sensors throughout a full cycle so this can be assessed and we can do this by sampling the current multiple times throughout the 50Hz cycle to  calculate the aggregate current.

Reasonable number of samples

Each current data point sample has to be individually processed (read, scaled and logged). To give a reasonable approximation of the current flowing throughout the cycle, I insisted that a minimum of 10 samples are taken each cycle

This means the sample frequency needs to be at least 500hz per channel to sample a 50Hz cycle. Both the output from the Grid tie inverter and Grid feed need to be sampled. My first design used the ESP8266 ESP01S card which was able to achieve this but the I2C bus connecting the ADS1115 to it was having problems keeping up switching between the two channels and all the other processing.

The Grid connection in my perception is the most dynamic link, potentially switching direction more times  than the other sample point. I decided to over sample this link while maintaining the 500hz minimum for the Grid Tie Inverter so I started using the ESP12

This was marginally more expensive than ESP01S but provided access to a 12bit on board ADC that allowed for this oversampling.

This combination worked well but meant only one channel of the 4 Channel ADS1115 was being used.

Having two components is more costly. The cost of ADS1115 plus the cost of the ESP8266 ESP12 is more expensive than the  ESP32-S2-WROOM  (which supports multiple ADCs). So I have redesigned the PCB to use this processor.

Posted on by — Leave a comment

Power and the grid

The power to the house is from the National Grid and our solar panels.

240V AC mains power

In the UK mains power is supplied from the National Grid. Alternating Current (AC) as voltage and current input is supplied as a nominal sinusoidal voltage of 240v RMS at 50 Hz with a peak to peak of about 338v. In reality this varies between 216 and 253 RMS. The voltage from the Grid goes from 0 volts to +338 volts down to -338 volts in 20 milliseconds. It repeats this 50 times a second (1000ms).

Resistive load

On the very simplest level a house is a resistive load. The voltage inside your house will follow a similar sinewave voltage at a slightly lower voltage because of the resistance in the wires of the Grid and inside your house.

Mains 240V AC ->
--> House Load AC

The voltage at the substation (on the Grid) will be more than that at the resistive load of the house and therefore the current will flow into the house from the Grid, through the electricity meter.

Grid tie inverter

Solar panels on the house generate electricity as Direct Current (DC). DC is fed in to a Grid tie inverter. The inverter inspects the sine wave voltage that is generated by the Grid as seen at the resistive load of the house and creates a matching sine wave voltage  slightly above that of the house. This will cause current to flow from the Grid tie inverter through to the house and if there is enough power from the solar panels, out onto the Grid.

Grid <--
<-- Grid tie inverter

So the power consumption of the house will approximate to 240Volts RMS multiplied by the current into the house from the Grid plus that  from the Grid tie inverter from the solar panels. Because the loads used in the house are not purely resistive this is not the whole store but it is a fairly good approximation.

Power management and current flow

To truly calculate the power usage, we would need to measure the voltage and the current profile throughout each cycle. In power management our aim is to manage the current supplied to the house so that we may use locally generated current rather than draw from the Grid. Power management rather than accurate power monitoring. Knowing the current flow is sufficient to achieve this if we also know the direction of flow. Both the Grid tie inverter and the National Grid will determine the voltage dynamically but use of the 240V RMS value will suffice to estimate power usage for our power management needs. Some electricity meters offer an LED that becomes solid lit when current is flowing out of the house and pulses when current is consumed by the house.

Posted on by — Leave a comment

CU monitor redesign ?

The latest PCBs for the CU monitor arrived this week. They were supposed to be the test batch to prove the release of the CU Monitors to the website. There followed a frustrating two days of soldering up and testing. Essentially I had the surface mount ADS1115 that needed to be soldered onto the board. These are tiny chips that can be tricky to solder. After soldering 3 boards I had one that worked intermittently and two that just plain failed to work. So I looked at the working one on the bus analyser and the timing of the I2C bus seemed to be causing a lot of NAKs. After tweaking the software driver, this became a lot more reliable, which suggested the bus layout on the PCB was bad! making the communication timing marginal.

This means this will not be the last board! This got me thinking. The ADS1115 is a fairly low cost  16 bit A to D converter, initially I chose this chip because it was a module that lends itself to rapid prototyping but it has 4 channels and is accessed across an I2C bus. This chip  has caused me to redesign the CU Monitor PCB in the past because we are reading more than one channel rapidly it can cause significant slow down in the sample rate. Currently the CU monitor only uses one of the channels to boost the read speed. This makes this chip way over specified for our purpose.

So I intend to reassess the use of this chip and I will create a sequence of design/posts and explain my design decisions to document this procedure and help me get it straight in my mind

Posted on by — Leave a comment

Web RD

Web RD a simple development project aims to connect a display as cheaply as possible to the internet. This development is intended for anyone wishing to display information available online without actually requiring a separate device. The Web RD PCB is available in our store. This will allow you to build your own project without recourse to hardware design. The Web Rd development consists of :

  • CP2102 USB to TTL Serial Converter
  • WebRD PCB or Assembled WebRD Module
  • MAX7219 Dot matrix LED Display
  • USB Male to Female Extension lead
  • ESP8266 ESP01S

The CP2102 is a low cost stable and reliable way to connect a project to the power providing both 5V and 3.3v outputs. I’ve run them for thousands of hours with no problem. Powering a Project can can be an issue. This piece of test gear does the trick nicely.

The MAX7219 Dot matrix LED display is the low cost way to display large text.

The ESP8266 ESP01S is a very capable processor that provides plenty of processing power and a very cost-effective way of connecting to the internet.

We have available in our store 3d printed enclosures that provide housing for the display available in a mixture of colours

There are many use cases that make use of the Web Rd

  • Web Clock
  • Network connectivity display
  • Twitch Account display
  • UTube account display
  • Stock price ticker

For more information see

Posted on by — Leave a comment

CU monitor

The CU monitor is a development designed to calculate the current flowing to the consumer unit  from the grid and solar panels, broadcast is within the LAN and record the data to a website. I have taken a minimalist approach to keep the costs down. It uses two current clamps to measure the current

 

Current clamp sensor

One is clipped around one of the single core cables to the consumer unit into the house from the grid and the other other is clipped around the one of the single core cables that come from the solar panels inverter.

These connections provide the minimum number of connections. We have an algorithm that predicts whether the grid connection is importing or exporting to the grid from the profiles of the currents observed on these clamps.

The CU monitor also provides an optional photo resistor input that can be blue tacked to the front of your electricity meter as some electricity meters have an LED that becomes illuminated when power is being exported to the Grid. This can offer a confirmation that our algorithm is correct.

CU monitor Hardware

The CU monitor kit comprises our own PCB which hosts a processor that is used to calculate the AC current flow and records it to our display website. The PCB may be powered either by a USB lead or via a 240V mains power plug. The electronics are housed in an IP55 mini Junction box.

USB connection kit (no soldering required)

  • CP2102 USB to TTL Serial Converter
  • 2 or 4 Female to Female Jumper wire
  • USB extension cable
  • USB Cable
  • USB power brick or available USB socket

Mains powered kit (minimal soldering):

  • Hi Link 3.3V  3W P/N HLK-PM03
  • Varistor
  • Power Block

Either power system will suffice. The USB connection requires no actual soldering and  does not require the user to handle mains AC power. If you are comfortable  wiring into the mains power then the other kit is available.

disclaimer: handling mains voltage can be very dangerous. Do not do so unless you are qualified and comfortable with the wiring and connecting of mains power.

 

 
IP55 mini Junction box
Posted on by — Leave a comment

Solar panels

Many years ago I joined the Government’s FIT scheme and had solar panels installed. They have worked well so far but we only had a vague idea of how the energy they produced was being used. So I decided to develop a device to quantify and record the power usage. I wanted to make this device available to other owners of solar panels who may wish to find out more about quantity of power they produce from their solar panels to know how to predict their future usage.

The CU monitor is my attempt to make the energy usage profiles that our solar panels produce easily accessible. This will allow me to make informed choices on electrical power questions.