Hey guys,

My name is Mike. I came over here after talking to Pete.

I am looking to make a module to control some LED tail lights in a "Chase" pattern. Its similar to the sequential, but instead of each light, lighting up and staying on during the pattern, the lights will come on and go back off as the next light is being lit up.

I am starting my research, with the help of Pete, and am trying to learn everything about programming these chips as well as what parts I need to buy in order to do it.

So I will be hanging out here for a while.

Looking forward to hearing and learning from you guys!!!

Welcome.

It sounds like you already have a good mentor but don't be backwards in coming forward if you get stuck.

The idea here is to use a picaxe to do the sequence, and is what Mike is about to get a bapthtisum of fire with

Here is the first draft of a schematic so the rest of you can see the basics of the project.

Note that the resistor values might not be correct for the full circuit, and i expect the led lights are already setup for 12 volt operation so no limiting resistors shown.

Pete.

Why high-side drivers, and will they even work in that configuration?

Because as far as i know most car tail light assembles have a common chassi ground and are high side switched. (bugger)

No it dont appear they will work in that configuration. (bugger,bugger)

Any ideas on a high side driver, brains?

Pete.

Duly Noted !! Any advice is GREAT advice.



Ut Oh, what did I get myself into?!?! Fire !!

Transistors aren't my strong point, but I think you have to use PNPs as the drivers with bases pulled to 12v with resistors to turn them off. Then pull the PNP bases low (through another resistor) with NPNs to turn them on.

You could use relays, or those small SS relays.


Only if you get the wiring wrong

Here's how I think a high-side driver would work.



But as I said, transistor aren't my bag.

What are you like on mosfets.
Do you have a bag of ideas on them?

Pete.

Same as I am with transistors, whatever that means

It's essentially the same circuit with resistors upped because MosFETs don't need any current.



This is better in that there will be bugger all heat generated, worse because FETs are very susceptible to ESD and these wires will presumably be running the length of a vehicle.

In either case the high-side transistor has to have the base/gate pulled up to 12v or it won't turn off. That's why you can't drive them directly from 5v on a 12v system.

There are however special high-side driver FETs that boost the gate voltage internally.