hi,
ok..
i build f1ring systems for big f1reworks displays and i'm currently building some new units that can be programmed by a PC using the USB port.. each unit will be able to fire 16 f1reworks.. it will hold 6 standard patterns and 2 custom patterns downloaded from the PC.. it will also have 8 standard speeds to run these patterns..
for example it could fire all channels sequentialy@1 second intervals:
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16
or:
1 + 9, 2 + 10, 3 + 11, 4 + 12, 5 + 13, 6 + 14, 7 + 15, 8 + 16
..etc
going to have three push buttons.. one that selects the Pattern, one that selects the speed (for the built in patterns), and one that when you press it it will preview the pattern on the output leds.. two of the 8bit I2C bus expanders will just have the status leds on them.. 8 for pattern and 8 for speed.. when the preview button is hit it will sequence through its sequence outputting it onto the LEDs.. the other two 8 bit I2C bus expanders get connected to darlington arrays..
ok so thats the unit.. the idea is that this unit can be plugged into any other f1ring system.. some use 6v other 12v, others 24v..etc when these f1ring systems test the system to check that there are f1reworks on the channels there are supposed to be it test fires the circuit with the f1ring voltage but limited to 10-20mA just to show continuity..
these units then get wired into one of the channels on the main f1ring system.. when the system tests that channel it puts say 12v @ 10-20mA down the line.. the PIC needs to know NOT to fire the sequence.. when the display comes along and the system presents 12v at as much current as it can get through its darlington arrays the unit needs to fire its sequence. the f1ring voltage is only on for 500ms which is enough to fire the f1ring caps.
thanks
chris
p.s. sorry for the secrecy and the funny numbers, this sort of thing is important to keep quiet from other companies.. (as he posts the whole design of the system on the net ;-))