start and stop dates for the indefinite future, but that was
hard because the DST rules are rather informal: “DST
starts at 2 am on the second Sunday in March and ends at
2 am on the first Sunday of November.” Instead, I just
made a table with the DST start/stop dates for the next 15
years and I use that to adjust the inputs from these
time/date sites.
50-Pin RCM5450W Repeater
Early in this project — as I was debugging my initial
code for controlling relays — I was faced with a mystery:
The relays were “chattering,” implying one or more of
them was turning on and off rapidly, or maybe the relay
drive circuit was behaving erratically. To track the problem
down, I wanted to use my scope and my logic analyzer,
but there were no convenient places to attach the probes
because the guy who designed the board (me) had not
provided any. I fixed that omission on the next revision of
the board by bringing every module interface signal to a
pin staked to the board in a standard 1/10” configuration.
That turned out to be a really good idea (although it was
by no means trivial to hand route all 50 lines from the
Rabbit socket over to the pin field), but it got even better
when I remembered to label each pin on the next board
rev’s silkscreen.
Rabbit’s C Compiler
The Rabbit RCM module is
available from Digi-Key. The Rabbit C
compiler is available free from Rabbit
at www.rabbit.com/support/
downloads/dc/ dc10.shtml. Then, all
you need is a programming cable
(available for $39 at www.rabbit.
com/products/usb-prg-cable/
buyOnline.shtml). The rest of the
code and files needed for this project
can be found at the article download
link. There is also a README file
which describes the various files and
directory structures.
Wrap-Up
TCPmaker for control over the Web
Simple Upgrade Management System
Easy as 1-2-3:
1. Define Your Data, with variable names that
YOU create.
2. Lay Out Your Content (with gorgeous
web-ready screen controls that you can grab
on to ) using TCPmaker’s drag & drop Visual
Page Designer.
3. Generate Your Code, for all Microchip C
compilers, to “wire it all together.”
NO PC PROGRAMMING AT ALL – just point your
web browser at your device!
Low cost integrated system manages upgrades
across different processors & connectivity types:
> Lets your end users upgrade your PIC
firmware safely, simply, and securely.
> Automatically delivers upgrade by email.
> Simple for non-technical end users.
> Encrypted system protects your firmware
from theft or from being programmed into the
wrong device.
> Grows with your product line: for a new
product w/ different processor or connectivity
type, just add another SUMS bootloader.
This article has covered the
basics of the Wi-Fi sprinkler project
hardware. I’ve tried to give some
rationale for the choices made in its
design, including the LCD and relay
interfaces which will impact the
programming necessary to make all
this work. Besides making a dandy
sprinkler system controller, this
design is very general – a low cost,
networked, wireless controller that
knows the date and time, has a Flash
file system beneath it, lots of sample
code, and is a lot of fun. Use it for
sensing, controlling, monitoring …
your imagination is the limit. I have a
couple of things in mind already.
NV
www.tracesystemsinc.com
888-474-1041
From the makers of HIDmaker FS:
Bob Colwell was Intel’s chief Pentium
microprocessor architect for most of the
1990’s. Before that he was a hardware
engineer at VLIW minisupercomputer
startup Multiflow Computer, a hardware
design engineer at workstation vendor
Perq Systems, and a member of technical
staff at Bell Labs. He has 40 patents and is
the author of The Pentium Chronicles. He
is currently an independent consultant.
40
February 2011
