555 question

What did someone say, the PIC10 and 12 series are the 555 of today? I would just about agree, with a little programming you could do the above without all the external support parts. Use the internal RC osc and you are on your way. Just look for the edge, do the output "thing" and wait for the next edge, rising or falling, it's up to you.

Jim

Search on this page for differentiator.

--- View in Courier:

+V>----+-----------+------+-------+--------+---------------+ | | |K | |8 | [10K] [100K] [1N4148] [750K] +---+---+ | | | | | 2|_ Vcc |3 | +--[0.1µF]--+------+-------|---O|T OUT|--->OUT | | | 6| | | | +----|TH | |C1 | O | 7|_ 555| [0.1µF] S1-->| +---O|D | | | O | | GND | | | |+ +---+---+ | | [1µF] |1 | | | | | GND>---+--------------------------+--------+---------------+

C1 goes directly across pins 1 and 8

-- JF

Need some theory help here. :-) What's going on with the 10k, .1uF, 100k, and diode? While the button is up, I'm thinking that 10K charges that side of the cap faster (obviously), keeping the trigger high as the charging goes on. Then when the button is pushed, that side of the cap is yanked to ground causing the other side to do basically the same thing resulting in triggering the 555. While the button is held down, the right side (100k side) of the cap proceeds to charge back to +V thru the 100K resistor. When the button is released, the left side begins charging towards the V+ rail possibly causing the right side to attempt to rise above V+. The diode stands in the way of that letting the extra voltage dump into the V+ rail. Is that close?

Show us your code. :-) Them's the rules. If you say "use a pic" you're obligated to show how it's done. ;-)

.+V>----+-----------+------+-------+--------+---------------+ . | | |K | |8 | . [10K] [100K] [1N4148] [750K] +---+---+ | . | | | | 2|_ Vcc |3 | . +--[0.1µF]--+------+-------|---O|T OUT|--->OUT | . | | 6| | | . | +----|TH | |C1 . | O | 7|_ 555| [0.1µF] . S1->| +---O|D | | . | O | | GND | | . | |+ +---+---+ | . | [1µF] |1 | . | | | | .GND>---+--------------------------+--------+---------------+

--
Yup!

.+V>----+-----------+------+-------+--------+---------------+ . | | |K | |8 | . [10K] [100K] [1N4148] [750K] +---+---+ | . | | | | 2|_ Vcc |3 | . +--[0.1µF]--+------+-------|---O|T OUT|--->OUT | . | | 6| | | . | +----|TH | |C1 . | O | 7|_ 7555| [0.1µF] .S1-->| +---O|D | | . | O | | GND | | . | |+ +---+---+ | . | [1µF] |1 | . | | | | .GND>---+--------------------------+--------+---------------+

--- Oops... for minimum current draw, you should use a 7555, and if it can't source enough current for your sensors use it to drive a transistor or MOSFET that can.

--
JF

Clever :-)

Hear, hear!

Thanks, Rich

Of course the next time you suggest a 555, you have to post a schematic as well. ;-)

PSST! This is a non binaries group! Redirect them to A.B.S.E. or there can be no schematic posted excepting only crappy ASCII art.

How's this?

while(TRUE) { if(edge_hightolow() && timed_out()) handle_output(); }

or

while(TRUE) { if(edge_lowtohigh() && timed_out()) handle_output(); }

Now, just fill in the functions..... ;)

Jim

Yeah, why don't I just go ahead and do that while you go outside and play "hide and go f*ck yourself"?

Cheers! Bobo

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Cheers!
Rich^H^H^H^HBoBo