(I still haven't decided what to do with the serial in/out pins yet. It's either tie them to 0V or connect them a 3.5mm jack so the Picaxe can be programmed in place.)
How it works
The combination of R1-R2-C1-C2 form a 2nd order low pass filter which attenuates (reduces) frequencies above 338'ish Hz. (design centers around a maximum reed switch frequency of 290 Hz @120 Mph)
D6 is a voltage 'dropping' diode which lowers the supply voltage (5.0V) by .4 or so volts (it all depends on the amount of current flowing).
D3-D4 are used as transient suppressors. (can't have static destroying components can we!) When the reed switch in the speedometer is closed, diodes D3 and D4 conduct whenever the voltage tries to go over 5.0V OR below -.4V (current flows in a loop) When the reed switch is open those same diodes conduct at approximately .4V OR -.4V (Rail voltage 4.6V OR .0V depending on if the reed switch is open or closed)
R3-R4-C3-C4 are 2nd order low pass filters for the cancel circuit (there are low pass filters at the input of Q1 and Q2 as well), keeping 'noise' from false triggering the Right, Left and Cancel circuits.
(hey! I didn't push that switch, why are the turn signals on?) D1 and D2 are the transient suppressors for the cancel circuit.
U1 is the microcontroller (µC) that takes the input from the reed switch, right, left and cancel switches and uses those inputs to pull either the reset (RST) or trigger (TRIG) lines of U3 low (near 0 Volts) turning on or off the signals.
U3 (U3.1-2-3) is a bi-stable flip flop (stable in the 'on or off' condition until triggered in the opposite state)
Q3 and Q5 (Q4-Q6 also) are nothing more than an electronic relay allowing current to flow from turn signal flasher to the turn signals.
U2 is a 5 volt regulator which powers the device.
D8 is to protect from a battery being connected backwards.
D5-D7-D9-D10 are also transient suppressors to protect their associated circuits.
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A BIG thanks to Duanage for his help getting this portion of the project started and to Robert Barr and Wallogreen (Martin) for their input and help as well.
'Banging the bits' software design in progress.
Wish me luck!
EDIT*** Uploaded latest iteration 05-17-14
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