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Emergency Vehicle Strobe Light Pattern Indicator

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Black-Wolf

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To anyone who is willing to help, let me say thank you right now.

First, I have some basic knowledge of how circuits work. I was an aircraft electrician for 18 years, so I understand basic terminology, and also some more advanced concepts.

Here's my problem: I'm now a volunteer fire-fighter/EMT. I installed a strobe kit and switch set which I built myself, to power the strobes and switch the patterns for them.

What I would like to do, is add a digital counter that will count from 1-24 (the number of the pattern). The counter should increase each time I press the Flash Pattern Change switch, until it reaches 24, and then it should reset back to 1. I understand the basic idea of how to do this using gates/flip-flops, or perhaps a PIC or an 74LS192 or 373.

At this point, I'm honestly thinking a 373 would work better for my needs.

There are five switches that control the strobes as well as two other switches for a pair of grille mounted lights. The switches for the strobes are:

Switch 1: Master Power (controls both the grille lights and the strobes)
Switch 2: Hi-Low Power
Switch 3: Heads 1-4
Switch 4: Heads 5 & 6
Switch 5: Change Flash Pattern (Increment from pattern 1 through pattern 24, at which time it resets to pattern 1).

Here are my questions:
1) When turning off the master power switch, how do I "kill" the display for the two LED displays, WITHOUT losing the value that they are currently set on?

2) When turning the master power back on, how do I reload the current value to the LEDs?

3) If constant power must be provided to the circuit to keep the current value, how do I make the LED Numeric display go black or look like it is off, again, while maintaining the value they currently display?

4) Are there any LED numeric displays out there that are "dimmable" - that is, I want to be able to wire them into my vehicle's instrument lighting system and have them dim as I adjust the rheostat... I am assuming that if there is such a thing, I could just figure out the appropriate resistor to plug in between the instrument cluster lights and the digital display.

5) I would also like to consider a more advanced circuit - one which has a text display (say 15 characters) which can be either scrollable or steady, but which would display, for example: "PAT1: Single Simul Flash" or "Pattern 2: Single Alternating Flash" or something similar. What sort of chip(s) would I need to do run this, and how would I program the text in (I'm assuming a patch cable into my PC or something similar?)

Again, any help you can give will be greatly appreciated!

I have uploaded the wiring diagram for the switches so you can see how it's wired (in case that might help).

Thanks!

V/R

Black-Wolf
Bennett VFD.
 

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  • 7ButtonSwitchWireDiagram.pdf
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Think "digital clock". It does many of the tings you need. It requires +12, ACC, and a DIM input.

The Texas Instruments MPS430 processor has various modes and therefore you can put it to sleep so it consumes very little power. This is one way of handling the problem. LCD displays such as on your Laptop change the brightness of the backlight.

Here is some examples of displays: Serial Display Modules

I^C and SPI are other comunications interfaces

Take a look here: **broken link removed** and CPUStick. The previous uses this OS.

Also take a look here: Microchip Technology Inc. is a Leading Provider of Microcontroller and Analog Semiconductors, providing low-risk product development, lower total system cost and faster time to market for thousands of diverse customer applications worldwide.

So the issue is to find a processor which can be placed in a low power mode.

Analog inputs can be conditioned to accept the DIM signal and provide the commands for the display.

Inputs can be suitably debounced and an output used to interface to your device. Seems like you need a way to sync your device with the strobe and therefore it makes more sense to interface to the processor and have the processor interface to the strobe module.

LED displays for a car have a habit of getting washed out. So a backlit LCD or vacuum florescent is usually used.

While you can take two digits and do the multiplexing in software, it's difficult.

Here is some info on the MSP 430. MSP430 LaunchPad Value Line Development kit - MSP-EXP430G2 - TI Tool Folder A development system is available for $4.30. No, it's not programmable in BASIC and that particular processor may or may not have the capabilities you need.

In many cases the archetecture is scaleable.

The CPUSTICK website has a DOS application which can be used to evaluate the BASIC.

Do some reading.
 
Excellent advice KISS. Some of that might work for what I want, w/o me having to build the system completely from scratch. The price is right on the CPUStick stuff too. Plus, I know VB so jumping to BASIC shouldn't be too big of a stretch for me. Patching directly into the stobe system is probably not an option however, as it uses high voltage on all the outputs to the strobes, and patching into the box itself will void the warranty that came with it. Patching into the inputs would be the same as just doing it at the switches in the controller box, but with more wire...

Thanks!

Anyone else, I'm still open to other suggestions. I'm not just going to jump into this w/o reading a lot more (I've already been reading for days now). Note: As the controller box with the switches is located under my steering column, washout from sunlight is not really a problem, but if I move the box onto my dash, I suppose it could be later.

V/R

Black-Wolf
 
Most of my microcontroller and microcomputer experience comes from 30+ years ago and included a gantry crane for a model rail road. I have a few projects of my own I'd like to do:

1. (car) Buzzer for x seconds on first transition of speedometer sensor transition after brake on. (low power)
2. (audio) Generate pulses based on edges of AC inputs. (low cost)
3. (car) Glitchless power-on delay timer (low cost)
4. (sensor) Allow replacing of one thermistor sensor with another using a different curve.

Unfortunately, priorities are elsewhere.
 
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