The RGB LED Colour wash has proved to be
very popular and has been the most frequently downloaded code on the
site since it was made available. The section in the original PIC
Projects page for the LED colour wash got so long I decided to give it a
page of its own. If you want to build your own RGB LED controller
read on.
For 2006 I've completely rewritten the
application. It's now much easier to add, edit and change the
sequence data. It also now has a sleep function so a battery
operated version can be built that doesn't need a power switch.
The new code runs on the 12F629, 12F675 and the newer 12F683 which, with
2K of program memory has plenty of room for user sequences.
I now also have working an RGB PWM driver
that is controlled over a serial interface. Each RGB driver will
receive data from a PCs RS232 interface, or standalone controller and
they will all run in sync with each other. (Full
details here)
Finally here's some photo's of the
controller software described here operating with Kingbright XPower LED
modules. These LED's are really bright. Note: the output driver has been
modified to use BS170 mosfets. (XPower LEDs are available from http://www.rapidelectronics.co.uk/)
Another LED I've tried is made by Lamina Ceramics. Their latest
product is called the Atlas and the RGB version has 6 LED dies (2 x red,
2 x green, 2 x blue) in a single package. It operates at 350mA and
is the best 350mA LED I've seen, the brightness is exceptional.
Available in the UK from http://www.leds.co.uk/ (the Atlas LED
is not currently listed on the web site but if you contact them they can
supply it)
More details of this and
the other developments will be appearing on this page over the next few
months. August 2006.
The original RGB PWM driver application
that I wrote in 2004 had a few shortcomings. Probably the biggest was
that it was not easy to add to or change the sequences. This new
version addresses that problem, is more flexible and now includes the
ability to put the PIC to 'sleep' and 'wake' it again using the sequence
select switch, eliminating the need for an on/off switch in battery
powered applications.
The circuit uses (RGB) Red, Green and Blue
high brightness LEDs that are pulse width modulated (PWM) to vary the
intensity of each colour LED. This allows effectively any colour
to be generated with rapid changing strobe effects, fast and slow colour
fades as well as static colours. The data used to set and
change the colours is held in an easy to edit file so if you don't like
the sequences provided with it, you can modify the sequence data include
file yourself and reprogram with your own sequences.
The code can be assembled for use with the
following PICs: 12F629, 12F675, 12F683. Just select the correct
processor in the MPLAB IDE before assembling.
If you are currently using the old version
of the RGB PWM code (light10.asm) you can reprogram the PIC with the new
version of code as it is fully compatible with the original
PCB.
When the PIC is first powered on after
programming, it should start running the first RGB sequence found. If
you're using the original sequences supplied with the code here it
will run a sequence of red-fade out, green-fade out, blue-fade out
repeatedly.
Press the SW1 sequence select switch to
step through all available sequences. When the last sequence has been
reached it will go back to the first available sequence. Each
time the SW1 switch is pressed the RGB LED PWM values are set back to
0 (LEDs off)
Press and hold SW1 switch for about 1.2
seconds to put the PIC into sleep mode. Once in sleep mode,
press the SW1 switch for about 2 seconds then release it to wake the
PIC from sleep. If the SW1 button isn't held for two seconds the PIC
returns to sleep - this prevents the circuit from being accidentally
turned on. When operating the RGB controller from
batteries (without a 78L05 regulator) a power on/off switch is no
longer needed since the PIC uses only a few microamps when
'sleeping'
About 10 seconds after the SW1 sequence
switch is last pressed the currently selected sequence number is saved
to non-volatile EEPROM memory. When the RGB LED driver is next
powered on, the saved sequence number is read back and will
automatically start running.
Anytime the PIC is put into sleep mode
by holding SW1 switch down, the currently selected sequence is also
saved to EEPROM.
Source Code (rgbsa-inet.asm -
23/06/2006) The source code comprises a single .ASM file and four
.INC files. All five files are required and should be extracted
to a single directory on your computer. To reassemble the code,
open the rgbsa-inet.asm file, then select Project - Quick Build from
the MPLAB IDE menu bar.
Programmer
ready .HEX files Hex for 12F629 and 12F675 (right-click Save
As) Hex for 12F683 (right-click Save As) (please read
the FAQ
below)
Schematic JPEG , PDF If you build the battery version shown in the
schematic, the power on/off switch is no longer needed since the SW1
switch can be used to put the PIC into sleep mode and wake it up
again
PCB version Front, Back, Lit The LEDs and switch are tacked onto the track
side of the PCB with rest of the components mounted normally, this
looks much better when it's mounted in a light fitting. These photo's
show the original PCB design. The artwork below is the third
revision I've done and puts the switch in a better position on the
board.
The data used
by the application for the RGB sequences is held in the file
'sequenceData.inc' You can edit this file to add, remove or
change the data provided. You must ensure that it follows the
format described. In particular pay attention to the 'end of
sequence' and 'end of all data' markers and also ensure that each line
of sequence data contains five comma separated entries. (see screen dump
below)
In the screen
dump above note the 'end_of_sequence' markers circled in red and the 'end_of_all_data' marker circled in
purple.
You must have
at least one sequence present up to a maximum of 256 individual
sequences, although you're likely to run out of available memory on the
PIC before you reach this limit.
Each line of
data starts with a 'dt' (data table) assembler directive.
All data is
specified using decimal values.
Each data value must be separated by a
comma
The sequence
data on each line has five fields:
Fade Rate:
speed the colours fade from the current values to the new values.
Each step occurs at an interval of 5ms x Fade Rate.
Fade Rate
value of 0 indicates the RGB values will be updated immediately
without fading.
Fade Rate
value must not be set to 255 except to indicate end of
sequence. (see d. below)
Hold Time:
after fade completes, delay before moving to next line of data.
Interval is 50mS x Hold Time
Hold Time
value of 255 following a Fade Rate of 255 indicates
end_of_all_sequence data.
Red, Green
and Blue PWM values. 0 = 0% (LED off) through to 255 = 100%
(LED fully on)
Typically changes in LED brightness are more
noticeable between 0 and 128 than from 128 to 255.
End of the
current sequence data is indicated by the Fade Rate field being set to
'255'. When the application encounters this it restarts the
sequence from the beginning.
At the end of
all available sequence data both the Fade Rate and Hold Time fields
must be set to '255'
After editing
sequenceData.inc the file should be saved and the
rgbsa-inet.asm reassembled. The resulting rgbsa-inet.hex
file can them be programmed into the PIC.
Saving the
Internal Oscillator calibration instruction.
This only
applies to the 12F629 & 12F675. The 12F683 uses a different
method for calibration
Rather than
explaining this myself, here's the section from the 12F675
datasheet. Your programmer software should read this value from
the PIC, then merge it with the .HEX file before programming.
Multiple RGB
lights not staying in sync This note follows a query I had from
someone who built these RGB lights. Because the timing is
generated from the internal 4Mhz oscillator and there is no way to
synchronize each device with others, even if they are running the same
sequence, the colours quickly get out of sync with each
other.
If you're
building a light bar or any application where you need more than one
unit and they need to stay in sync you should build the 'serial
controlled RGB driver'.
Oscillator
Calibration Instruction I've had
a number of enquiries from people who can't get the code to work and it
has transpired that they / their programmer has erased the OSCAL value.
Without the calibration RETLW instruction the code crashes so you must
ensure that it is present or the code will not run.
How can I
recalibrate the internal oscillator on a 12F629 or
12F675?
Microchip have published an application note and
software to allow you to recalibrate the internal oscillator and this
will of course allow you to find the correct value if you've
accidentally erased it. http://ww1.microchip.com/downloads/en/AppNotes/00250a.pdf
Search on Microchip's website for
"an250.zip" for the application code.
Verify
Errors after programming The RGB light programme code uses the
PICs EEPROM to store the last used mode. When the PIC is powered
up for the first time after it has been programmed it checks to see if
the last sequence value saved in EEPROM is less than or equal to the
number of available sequences. If it is not, the code set the value in
the EEPROM to 0.
I had a series of e-mails from a guy in Greece
who had lots of problems with "Verify 0000!" errors. I eventually
built the programmer hardware he was using and ran the software to try
and find out what was happening. It turned out that this
particular combination of programmer/software was powering up the PIC
between writing the code into the PIC and verifying it. This
caused the EEPROM to get initialised to "00" but the software was still
expecting "FF" so the verify failed.
The programmer hardware was
PLMS OziPIC'er and the software was IC-Prog 1.05D. I must stress
that apart from this idiosyncrasy this is a perfectly capable PIC
programming setup and once aware of what is happening it is easy to
account for and work around.
(A special thank you to Panagiotis from Athens - thanks to the
Internet, his excellent English and much patience we got to the bottom
of this problem despite the language barrier and the
distance)
Editing,
adding changing the RGB sequence data.
All the sequence data
is now held in the sequenceData.inc file so it is really easy to add
your own sequences. The application works out how many sequences
are present, where they start and finish and takes care of page boundary
crossing. All you have to do is put the correctly formatted data into
the file, save it then reassemble.
Please take your time when
editing the sequenceData.inc file since errors are likely to cause the
RGB Driver to do unexpected things or crash.
If you see an
'Warning [220]' error during assembly like that shown below, you've
added more sequence data than the PIC has available memory.
Clean: Deleting
intermediary and output files. Clean: Done. Executing: "C:\Program
Files\Microchip\MPASM Suite\MPAsmWin.exe" /q /p12F675 "rgbsa-inet.asm"
/l"rgbsa-inet.lst" /e"rgbsa-inet.err" Warning[220]
C:\CODE\RGBSA-INET.ASM 158 : Address exceeds maximum range for this
processor.
If you see
an Error [112] message during assembly check for missing comma
separators in the sequenceData.inc file
All information and software on
this website are provided "as is", and without warranty of any kind,
either express or implied.
In no event shall I be
liable to you or any third party for any consequential, incidental,
direct, indirect, special, punitive or other damagesarising out of the use or inability to use the
software and/ or hardware on this web site.
