On 16.10.13 01:04, Dave Cole wrote: > Don't over think this.. Personally I think a PIC is WAY over thinking > this.. a cheap PLC with relay outputs would be easier to work with > and more cost effective for a one off like this..(if it is even > required) Automation Direct has relay output PLCs for less than $100. > The programming software is free.
+1 Something that is ready to go, and programmable in the problem domain (i.e. already has commands which deal with the real world; controlling outputs and timing, as well as sense inputs), will give much quicker results. Having spent 30 years designing with microcontrollers (in telecommunications R&D), I'll offer these thoughts: 1) Both AVR and PIC have their fans, leaving other good contenders such as the MSP430 less popular. Beware of fans pushing their mascot, without fully considering your design issues. Any of them will do your job - after many weeks of learning, design, implementation, and debugging. Heck, even an AT89C2051 has the advantage of eliminating a lot of confusing on-chip hardware from one's first effort. 2) Availability of a bootloader is useful if you need to update the firmware in the field. Otherwise, it adds zero so long as you have a programmer for the device. These are dirt cheap, can be DIY, and can be as little as a few wires from a PC parallel port, in the case of AVR. If tackling a project which _must_work_flawlessly_on_the_night_, without some years of experience with 'C' and assembler programming, then please add a month or two to the project. The other big hurdle is mastering the on-chip hardware on an unfamiliar microcontroller - definitely non-trivial if it's your first. (On one project, I remember the hardware design team sending one of their guys to Australia from Tokyo, with the populated first system prototype under his arm, because it wouldn't do anything. I had chosen the micro, so my team had to help work out which clause of over 300 pages of manual had been overlooked in the circuit design. With perhaps 50 man-years of experience on tap, it was solved in a couple of hours.) A beginner under time pressure may struggle with a series of such device familiarisation experiences. 3) Hand-knitted prototypes can be less than robust. Wires soldered onto pins of devices stuck through matrix board don't endure tumbling around on a stage. If the solution must involve a microcontroller, then grab something like an Arduino, and build the IO on a plug-in daughterboard, which they insist on calling a "shield". 4) If it's DIY, build at _least_ two, and make all connection plug-in. Standing there on the night saying "I think the relay driver's futzed", with no plan B, is not a winning hand for the "man of the night" award. 5) The one essential ingredient in such a design project is time; time to learn, time to make mistakes, time to find them in the code, and time to fix and test and test. But plays don't run to split second schedules. Since remote control is needed anyway for initiation of one or more sequences, is there need for more automation than a PLC can readily provide? Erik -- Harrisberger's Fourth Law of the Lab: Experience is directly proportional to the amount of equipment ruined. ------------------------------------------------------------------------------ October Webinars: Code for Performance Free Intel webinars can help you accelerate application performance. Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most from the latest Intel processors and coprocessors. See abstracts and register > http://pubads.g.doubleclick.net/gampad/clk?id=60135031&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
