The KeyRack Interface Project

Submission by Mark Goodwin – Scenario, I am leaving my house, pat down pockets, glance at exposed surfaces and scream to SWMBO “Has anybody seen my keys?”

If you are lucky enough to have a biometric, card entry system or other electrical device that has removed the need for traditional aluminum or steel keys, then this project is not for you. However, if like me you manually open and close windows and doors then read on. I was fed up with constantly having to solve the riddle of the missing keys so I embarked on this project with the aim of automating my arrival and departure by using traditional keys which I would integrate into “Homevision” and Frank McAlinden’s “probe Zone Hub” and “FirM” to create a catchall solution which would resolve my “lost keys” situation while integrating into and enhancing my daily arrival and departure experience.

Introduction – Each household varies according to the persons inhabiting the living space, and living habits tend to vary according to the age, gender, number of residents, their income, lifestyle and religious practices. These factors tend to influence the need for and adoption of new technologies within the home. My habitat or living space consists of two able bodied adults who are interested in technology, however we often find ourselves having to find ways of automating the seemingly simple yet frustrating everyday tasks. On this occasion, we have decided to embark on the task of solving the mystery of the disappearing keys. Having tried every available or saleable item from whistling chains to glow in the dark key rings, house keys were still a problem and the only answer was to find a way to create a permanent yet visible base station that would integrate well with “homevision” I have assigned “Homevision” the task of automating the mundane yet essential tasks of a normal household so took this opportunity to combine the “power down” of my equipment and lighting with the house keys in what has come to be known as the “key rack interface”.

I immediately set about some research and looked into various potential solutions such as iButtons, RFID and Magnetic Tagging, all of which could be interlinked into a Home Automation System. Each had their technical advantages, however, they all fell short as they could not psychically store or hold the keys. Part of the answer presented itself from a past project by Shawn Boyle on his ‘Automated KeyRack’; it was a practical and cost effective solution. Its limitation was in its fixed cable length that connected to HomeVision. If the fixed length cable could be replaced by a cat5 cable, the KeyRack would have greater flexibility relating to placement and positioning.

After several conversations with Frank McAlinden (who I had previously collaborated with on the Probe Zone Hardware) lead to the conclusion that it was possible to re-engineering one of his Probe Zone Monitor board and use his newly developed HomeVison I/0 Expander to create a Cat5 enabled ‘KeyRack Interface’ for the HomeVision controller, with the addition of custom housing being designed to look aesthetically pleasing so it can blend into the homes surroundings.

The Concept – To have a control interface into my Home Automation system that can run specific automation modes of “arriving home” and “exiting home”, which also doubles as storage for keys. This would allow for me and Swimbo’s keys to be properly stored for later retrieval and provide us a method to setup the home when we arrive home to our specific requirements and upon exiting the home all zones being automatically checked and powered down.

Proposed Functions:-

Enter Home

Problem – On arriving home the house is often dark, I have too many remotes and the main light is too aggressive . Result is often a poor welcome after slaying dragons!

Solution – Place key (3.5mm plug) into relevant socket , all Zones in the home are scanned to check whether any equipment is switched on ,thus signalling that someone is home. If nobody is home a Macro is activated setting lights to specific levels dependent on the time of day. This also activates other functions such as TV/Cable or Music which are routed to the appropriate zones.

Result – Automatic Ambient Home Environment without the need for remotes or manual control . I am welcomed by my home and feel more relaxed.

Exit Home

Problem – When we try to leave in a hurry we don’t know where the keys are , equipment and lights have to be switched off in every zone not to mention looking for my wallet this equals Mega Stress .

Solution – When the key (3.5mm plug) is removed from the socket , all zones in the home are scanned by HomeVision + the Probe System for current status . If any equipment or lighting is on then it’s turned off and HomeVision sets the mode as being away from home.

Result – By removing the key (3.5mm plug) from the socket you have a single key Power down which allows you to leave the house quickly , safely and stress free .

Over ride

Problem – If someone is using equipment or lighting and another use wishes to leave for a short period HomeVision needs to be informed not to change the current Home status…

Solution – By activating the override toggle switch marked O/R any or all Keys (3.5mm plug) can be removed without the Exit Home settings being activated . This means that any home occupants can continue enjoying the facilities undisturbed.

Hardware Components

  • HomeVision – Home Automation Controller
  • Probe Zone Monitor – Used to hold Key(s) + User led indication
  • HomeVision I/O Expander – Interface between HomeVision + Keyrack
  • X10 CHIME Module – Status feedback for Override mode
  • 3.5mm Stereo Plugs – Used for keys
  • 12v power supply – Required to power the Probe Zone Monitor
  • Cat5 Cable – Cable required to connect the Keyrack to HV


  • HomeVision XL – Runs macros + reads the HV I/O Expander

Setting Up/Configuration

Hardware Integration & Configuration

1. Powered down the HomeVision controller and connected the HomeVision I/0 Expander hardware via a 14 pin cable to the HomeVisions Expansion Bus.

Figure 1: HomeVision I/0 Expander

2. Assigned the HomeVision I/0 Expander hardware a dedicated I2C Address by way of addressing its 3 programming pins. The KeyRack was given an I2C address of 116 (Device 3). If using standard HV software or 3A if using HomeVision XL software.

3. Removed one end of a Cat5 cable and stripped back the wires and proceeded to connect the Cat5 wires to the HomeVision I/0 Expander screw connectors (Input).

HomeVision I/0 Expander Connections:

CAT5 Cable HV I/O Expander Port
Green white Port 1
Green Port 2
Blue white Port 3
Blue Port 4
Orange white Port 5
Orange Port 6
Brown white +12v
Brown 0v

4. The connection tip of a 12v power supply was removed and wires stripped back. The positive (+) wire was then attached to the +12v output on the HV I/0 Expander with the Brown white cat5 wire . The Negative (-) wire connected to the 0v connection with the Brown cat5 wire. Please Note the +12v leg should be fused . Recommend using a reset able fuse rated at approx 100Ma.

5. Plugged in the Cat5 cable into the Probe Zone Monitor’s socket then re-connected the power supply to the HomeVision controller then proceeded to connect the power supply for the HV I/0 Expander. The led’s on the Probe Zone Monitor board lit up and displayed all six led’s as green, so all appears ok .


Figure 2: Probe Zone Monitor Board

Software Configuration

1. Edited the Windows registry to activate the ‘I2C’ commands in HomeVisionXL.

2. Created a macro for Homevision to read the status of the HV I/0 Expander. This macro forms the main mechanics for the KeyRack.

Figure 3: I2C Macro for the HV I/0 Expander


Figure 4: I2C Macro for the HV I/0 Expander

Testing the HV I/0 Expander

To test if HomeVision was reading the correct 12C states of the HV I/0 Expander, I inserted a Key (3.5m Stereo plug) into the Probe Zone Monitor sockets. Then I would check the appropriate variable . Also inserting a plug into any of the sockets causes the corresponding User Led to change displaying ‘Green’ to ‘Red’. I tested all 6 inputs and they changed status from ‘Green’ to ‘Red’.

Custom Housing & Hardware Modifications – With the prototype KeyRack interface up and running, the next stage was to design the KeyRack’s custom housing and the addition of a toggle switch to the Probe Zone Monitor’s circuit board to allow for an override function. As the KeyRack was to be on display within the home, not hidden out of sight in ‘Node 0’ or an Automation Closet, it was essential that the design be aesthetically pleasing with clean lines to complement my attempt at a minimalist feel. The clean lines are essential to ensure that the project achieves user buy in or acceptance as SWIMBO would reject anything too visually disturbing which can potentially disturb the decor and colour scheme. We had originally wanted a white square housing of similar size to the Probe Zone Monitor; however, Frank McAlinden spoke with the engravers who came up with the idea of using a brush aluminium finish with more of a wedge shape which was fantastic in concept but even better when the finished result was delivered.

Figures 5: Custom KeyRack Housing


Figures 6: Custom KeyRack Housing

Up and Running With the prototype Keyrack mechanics in full operation, the final stage was the design of the keyRack modes. Swimbo and I decided that the best way forward was to conduct an analysis of our living and social habits over a typical 24 hour period, this would then be checked against a weekday schedule and a weekend schedule. A separate schedule would be created to take into consideration any guests that we may be entertaining. Having worked out the schedule, we wrangled over whether we should use a chime to announce that an override to the system had been set. However, it was agreed that the chime should remain as it is important to know when the override is complete.

For the settings to work effectively we had to look at the habits and patterns of the users and put the moods into context as to who was present at what time. For example, I have a stressful job and on returning home, I enjoy an ambient environment including dimmed lights and soothing music. I therefore created a mood suitable for these purposes which I called the “arriving home mode” see table on weekday settings below. However, this mode is only effective if we do not have guests as the mood may be a little too relaxed. As part of this process we decided that anybody undertaking such a project should conduct a thorough contextual review of the settings and how they will make us and anyone who shares our habitat feel and the subconscious psychological cues that they may lend to any given setting.

It was also agreed that a separate group of settings be constructed for the weekend. Again, this was due to the desire to psychologically separate the weekend from weekdays. We looked at our behaviour patterns of a weekday and weekend and came to the conclusion that we prefer to unwind after work, whereas we prefer a higher octane weekend. We therefore took the decision to have brighter lighting, selected Music that was more upbeat and generally strove to create a balanced yet uplifting weekend environment that would support comfortable moseying, writing or reading, cooking and entertaining Guests. The weekday mode selection concentrated on maximum relation and de-stressing after a hard days work.

The Different Modes are described below for the “Weekday” settings:

Enter Home

Morning Mode [ 6am – 8am]

If I have an early morning jog , on my return , my usual morning settings are run.

The Bedroom TV is switched on and the Cable channel is changed for the News and Morning lighting set to 70%.

At Work Mode [8am – 6pm]

If anyone arrives home during working hours only the lighting mode is activated.

Whole house lighting set to 75%

Arrive Home Mode [6pm – 8pm]

On arriving home , lighting is dimmed and suitable ambient music is selected for the relaxed welcome home .

The CD Jukebox is switched on and the “Lounge Music” is selected for the Lounge and whole house lighting is set to 65%.

Evening Mode [8pm – 9pm]

If anyone arrives home late after a long day at work , a more soothing mode of music is selected with lower light levels .

The CD Jukebox is switched on and the “Mood Music” is selected for the Lounge and whole house lighting is set to 45% .

Late Evening Mode [9pm – 12am]

If we have been out , on return the entertainment system is activated displaying a list of programmes suitable for viewing .

PVR Mode is selected to see what TIVO has recorded for the Day ? and the Lounge lights are set for 30% .

Night Mode [12am – 6am]

If we have been out , on return only the lighting mode is selected.

Whole House Lighting is set to 20% with a global house timer set to power down all zones in 30 minutes.

Exit Home Mode

Available 24 hrs

Exit Home is a fixed Mode . It has been set to power down Equipment , lighting in all Zones and set Exit home flag. Actions
All Home Zones are scanned for Status , any equipment or lighting that is on is powered down and the “Away from Home” mode is set.


The Keyrack has been up and running for over 3 months with no problems. It has proven to be very responsive and stable. We have found it has provided us with a unique way to remove dependence on remote controls when setting up and powering down zones; to date we have not misplaced a set of keys since the implementation. The physical design has been a resounding success and SWMBO (she who must be obeyed) has remarked on the way it has slotted easily into our existing home routine while enhancing our overall automation experience in the home. She has found it simple, useful and aesthetically pleasing enough to have it mounted in our hallway. An excellent project with fantastic results.

This review provides an insight into some of the many possible uses of the HV I/0 Expander Interface created by Frank McAlinden. To find out more about the HV I/0 Expander interface please visit Laser Business Systems Ltd…

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