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SHOCK
Home Automation System
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SHOCK
is constantly evolving. Please check back for updates.
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SHOCK
is a system which I designed to control lights, cameras,
and various other devices in my home. I now have more than forty-two
devices connected inside my home including five digital thermometers,
a light sensor, a valve to fill my hot tub, and a video switcher for
my web cam (with panning). My system controls the temperature in four
zones (including my hot tub), garage doors, ten lights, and my alarm
system. The beauty of the system is that, no matter how many devices
are connected, the system speed remains nearly constant. I can monitor
and control all devices through any browser over the Internet (see
the working
demo page). Using the INetCam
software, I can also view the output of the video switcher.
SHOCK
is home automation system in which one computer controls and manages
many 'dumb' (non-computerized) devices. SHOCK is a wired system and
is based on Dallas
Semiconductor's 1-wire series of devices and runs on a Bagotronix
DOS Stamp computer module. SHOCK differs from other home-automation
systems in that device feedback is standard. Every I/O device communicates
with the control computer and communication errors are continuously
detected, logged, and corrected.
The control
system is completely configurable using a simple language which connects
the inputs and outputs of control 'blocks'. These blocks define input
modules, processing functions, and output modules. For example, you
might connect a light switch module directly to the input of a lamp
module. If your kids
are constantly leaving the light on, you may want to make it turn-off
after ten minutes. This can easily be done by inserting a timer block
between the switch and the light:
If you want
to control a light from two or more switches, just configure another
switch module to connect to the light module's input.
New
Features
I recently designed a 1-wire MSP430-112 interface module.
The module behaves similarly to the DS2407 bus has four inputs, three
outputs, and an IR reciever (finally I can control the lights from
my TV remote!). Of course, the board fits easily inside a standard
switch box.
SHOCK can
now be configured through a text file (config.txt). This means that
you can now build the SHOCK home automation system without compiling
any code! See the CONFIGURATION section.
A T-Bus controlled 1-of-8 video switcher and a servo output is used
to pan a camera horizontally using a standard R/C servo. The servo
output is switched between the cameras using the video switcher so
only one DOS Stamp output is required to pan all of the cameras. I
will soon add vertical panning and a simple pulse decoder.
The SHOCK software can now be compiled and run using Visual C++ 6.0
as a console app. Although there is no support for the T-Bus, the
"emulation" is useful for testing new function blocks and
overall program stability.
A wired
control system- are you NUTS?
Unlike the
X-10 system which communicates through existing power lines, SHOCK
is a wired control system. This means that every device module must
be wired to the control bus. Although running a set of wires to each
light switch in a house sounds insane, the task is worthwhile in light
of the advantages of such a system. All devices are connected using
only one set of wires: power, ground, data, and (optionally) direction.
The following illustration shows a simple bus configuration:
Features:
| Small
module size |
switch/output
modules fit into existing switch boxes |
| Transparent |
existing
light switches are used making the system transparent to the user |
| Multiple
device types |
discreate
input and output, analog input, and digital temperature sensors |
|
High-speed
|
lights
turn-on and off with no noticable delay |
| Flexible
|
switches
and software-configurable control blocks can be combined in almost
any imaginable configuration |
| Internet
Remote Control |
devices
can be controlled and monitored via a browser |
| Expandable |
using
bus amplifiers, there is almost no limit to the number of devices
which can be controlled |
Hardware
SHOCK hardware consists of the computer module, T-Bus (one-wire bus)
interface, 2x20 character LED display, keyboard, power supply, and
various I/O modules. The Bagotronix DOS Stamp was chosen as the computer
module due to its low-cost, simplicity, and features which include
a 40Mhz AM188ES core, 512K RAM, 128K FLASH disk, 16 digital I/O ports,
two serial ports, real-time clock, and Disk-On-Chip socket. It was
necessary to buy the optional 8M Disk-On-Chip in order to provide
sufficient storage for the program. A simple two-chip circuit interfaces
the DOS Stamp to the T-Bus and an optional LT694 provides watchdog
functionality (the watchdog resets the DOS Stamp in the event of a
crash). Below is a schematic of the interface. I added a watchdog
timer since the DOS Stamp's watchdog is permanently disabled at startup.
The keyboard is optional but is great for central control of temperature
"zones" and groups of lights.
This T-Bus
"extender" is just a two-way amplifier for the 1-wire bus.
Althought the 1-wire I/O devices present a very low load, the long
wires neccessary to control an entire house present a substantial
inductance to the TTL T-Bus output. The T-Bus extender allows the
bus to be split into two or more loads and does not require any additional
software overhead. Actually Dallas Semiconductor has addressed the
loading problem with their DS2409 MicroLAN Coupler device, but this
is simply a T-Bus controlled 1-to-2 multiplexor and requires substantial
programming overhead (it creates two completely independant networks).
My T-Bus extender is transparent to system operation although it does
require an extra wire for the direction control.
Software
The SHOCK program is written almost entirely
in C++ and is compiled using the freely available Borland Turbo C++
3.1 compiler. The program provides a low-level T-Bus interface combined
with high-level real-time control processing and a command prompt
for debugging and Internet interfacing. SHOCK is configured using
a simple connect-the-blocks scheme which is contained in separate
CONFIG.CPP module. Currently, any configuration change requires the
entire program to be built and uploaded to the controller. Eventually
the configuration will be read from a text file without the need to
re-make the program.
In addition
to a Turbo C++ 3.1 project, I have added compiler conditional statements
and created a Visual Studio 6 application which simulates SHOCK on
a PC. Although there is no I/O, this PC application can aid in testing
new function blocks and other basic operations.
Configuration
NEW! Shock is
now configured through a simple text configuration text file (config.txt)
which is read at runtime. The SHOCK program no longer needs to be
compiled every time the configuration is changed. Simply run the binary
(SHOCK.EXE) in the same directory as the configuration text file (config.txt).
Each line of the config file can either declare a new function block,
set an input to a constant value, or connect an output to an input.
For example:
new
input BathrmSw1 A2000000 19613346 A ;Declares a new switch on port
A
new input BathrmSw2 A2000000 19613346 B ;Declares another new switch
on port B
new output MyLight 9F000000 1961B212 B ;Declares a new output on port
B of a device
new gate MyAndGate ;declares a new AND gate
MyAndGate.gatetype = AND ;Makes the gate an AND gate.
BathrmSw1.out
> MyAndGate.inA
;Connect switch 1 to AND gate input A
BathrmSw2.out
> MyAndGate.inB
;Connect switch 2
to AND gate input B
MyAndGate > MyLight ; Connect output of AND gate to the light
Function block outputs can, of course, be connected to other function
blocks to make very complex circuits. Because the blocks are only
scanned when a value changes, these circuits are scanned completely
using 100% of the CPU resource. This also means that multiple outputs
can be connected to a single input. In the previous example, we could
have simply connected both switches to the light:
BathrmSw1
> MyLight
BathrmSw2 > MyLight
When either
switch is activated, its circuit is scanned so there is no contention.
Ouputs can
also be connected to mutiple inputs. The only rule is that feedback
loops must contain a FEEDBACK BUFFER block which prevents the scanning
of infinite loops.
There are currently four interface blocks and sixteen processing blocks
available as shown in the following table:
| Discrete-Input |
| Discrete Output |
| Temperature Sensor |
| A/D Input |
| Pulse Detector |
| Display |
| Compare |
| Delay |
| User-Adjust |
| Time Compare |
| Time Pulse |
| 4-Input Gate |
| Edge Trigger |
| Value Selector |
| 10-input OR Gate |
| FeedBack Buffer |
| Temperature Selector |
| Antifreeze |
| Byte-to-Discrete |
| Switch Timer |
