In terms of flash patterns, so am I. Anyway, just looking here: **broken link removed** I got overwelmed.
With flash patterns, i think of Knight Rider kind of things.
Seems like anywhere from 1 to 3 Amps as an output. So, ball park. Lets; hope you can measure the current that a lamp draws. A multimeter or a multimeter and a shunt or some other way.
There is definately going to be some terminology problems. For instance, a "dash display" already has issues. I'm thinking something like this:
https://www.sparkfun.com/products/9937
So, you'll have to learn programming, the PICAXE is programmed in BASIC ans should be very easy to learn. I2C is an inter integrated circuit communication bus that operates at 100, 400 kbps using 2 wires and ground, Typically it's a short bus, but can be extended. The PICAXE has instructions to implement that protocal. NXP defines the addresses of the chips which is how they make money.
So, if I'm making any sense, somewhere you have a controller. a Dash display (indicator) and a high powered display.
So, the Dash display can be one of these I/O expanders and a ULN2003 and possibly something to control the brightness of the LEDS. Dimming from the DASH lights. It's a complication that you may want to plan for.
In the old days, there was a rheostat the brought the dimmed power to the bulbs, Who nows what's used now. That dimmed voltage supply becomes the supply for the indicator. So, simplistically, it looks like a BAR LED display, a resistor for each LED. Powered by the dimmed 12V. The ULN2003 type chip drive the LED and the I2C I/O expander is a serial protocol cal that tells that circuit what lights need to be on. So, you have a small board and hopefuly a Bezel that needs a few wires to do it's dead.
** +12
** High current ground (10 LED (10*20 mA) is like 200 mA)
***+12 Dimmed source or logic DIM or the value of DIM etc.
(there are a few ways to implement dim)
SDL
SCL
Logic Ground
+3.3 or 5 probably
So, it might be 2 twisted pair foil shielded cable and three standard wires. Like an Ethernet cord and just wires.
Getting the I2C bus to operate over large distances is not imposable. Then, again, if the controller and the box are an integral part, you can dispense with the complexities of making the bus longer. So, no matter how many LEDS, up to about 128 (half of the 256 total), you don't need any more wires.
You would be doing nothing more than sending a serial stream continuously with delays. You'd be using the same bus, but sending the same data to the front and the back almost at the same time. A lamp test function?
Yea, there is stuff to learn about called logic translation and you may need 5V and 3.3 V. I'm after conceptual. Earlier, I brainstormed a user interface with parts pulled out of the air that may or may not exist.
Don;t mind me, I like to think out loud and include everything that I might like given infinite resources and time. When the design starts, it might take little effort to include the secondary parts of the design or you might leave it unpopulated or you might never implement it.
So, the high power version would be similar.
Larger wires for +12 and High current ground. You may or may not want an enable signal. t might be easy to add. It might not. You might incorporate a blown bulb signal. Again, a wait an see.
But the same thing happens. An I2C bus, high power +12, high power ground and some control signals like blown bulb or enable maybe.
You cam back at me and I suggested to measure the current. I'm asked what a dash indicator is. I briefly touched on a user interface and i gave an idea on how this thing might work.
Proof of concept of the "hello world" program is where you start. That "hello world" program might be 4 LEDS going back and forth and then the same program using I2C. Rethink the interface and try to figure out if the process chosen has enough resources.
In order to do the automotive environment right, you do have to pay more attention to managing transients.