So basically you have a hammer, so the task is to make every project look like a nail, so you can use the one tool you have, But then you end up using a A/D converter and FPGA and a Linux PC with a real-time operating system to run an air compressor motor.
But all you really need is a comparator to compare the current pressure to the desired, and close contact or not. On Sun, May 29, 2022 at 4:09 AM gene heskett <ghesk...@shentel.net> wrote: > On Sunday, 29 May 2022 01:56:23 EDT Chris Albertson wrote: > > So you want to be able to control the air pressure from within LCNC? > > One way is to have LCNC output a desired pressure then the air > > compressor just does what it is told. Use a $4 microprocessor (even > > an Arduino would work) to read the I2c and also read some output from > > the Mesa card. The Meas could just set a bit to control on/off or use > > PWM to send a desired pressure value > > > > The pressure regulation could be done by the compreoor > > More hardware I'd need to learn to program. Why bother when hal can do > it? hal can do all that. And I've been manually (from the axis gui) > controlling the peristaltic pump that delivers koolmist to the mister for > a couple years now, so adding another circuit in hal to throttle the pwm > to the compressor driver is for me, quite trivial. The sum2 module can > do the math. It should have been named math2. The name sum2 hides its > real abilities. It can do all 4 functions of a $6 calculator. hal has the > tools, they are in the toolbox so why not use them? pyvcp can even show > me the actual pressure in the gui if I can figure out how to calibrate > it. The biggest problem I can see is nuiquist related due to the somewhat > springy use of air screwing with the response time. hal can do that too, > its called a limit3, so I'd imagine I'll have to limit the rate of change > out of the sensor to keep it from oscillating. With the sensor watching > the output manifold, and 5 compressors running out of synch, the > pulsations in pressure will be far more than the average, which is what > I'm after. The lag in the i2c seriel channel of the sparkfun device will > add considerably to that tuning difficulty. > > > On Sat, May 28, 2022 at 10:33 PM gene heskett <ghesk...@shentel.net> > wrote: > > > On Sunday, 29 May 2022 00:21:48 EDT Chris Albertson wrote: > > > > This would be the sensor I would use. The link below is a very > > > > detailed gud that tells you how to use the sensor, including > > > > working > > > > example software. > > > > > > > > https://learn.sparkfun.com/tutorials/sparkfun-qwiic-micropressure-h > > > > ooku p-guide > > > > > > I've looked at that but I need an analog output I can op-amp up to > > > the > > > swing range I need. Mesa doesn't have an i2c interface that could > > > talk > > > to. I have some honeywell gage mode analogs coming from Mouser in > > > that > > > price range which can tolerate up to a 12 volt vcc, and that will > > > help > > > the noise budget considerably. But they won't ship till Teusday. > > > > > > > Yes, it is an absolute sensor but air pressure on Earth does not > > > > change that much/ If you really care a lot then use two pressure > > > > sensors, leaving one open to the ambient air. (But that would be > > > > over the top, nuts for an air mister) > > > > > > Agreed, just an offset to cancel the first 14.7 psia should work fine > > > too. > > > > > > > The interface is easy to use I2C using the pseudo-standard "QWIIC" > > > > connectors (physically JST connectors) The documentation is makes > > > > using this easy. > > > > > > But where do I find an i2c fed D/A? I didn't note such a beast at > > > Lady > > > Ada's place. > > > > > > > On Sat, May 28, 2022 at 8:44 AM gene heskett <ghesk...@shentel.net> > > > > > > wrote: > > > > > Greetings all; > > > > > > > > > > I'm getting frustrated, but I know it has to be out there, > > > > > someplace. > > > > > I need a differntial air pressure sensor, differential so it > > > > > references local barometric as its reference zero, and up to 10 > > > > > psi, > > > > > with a 3 wire analog output. > > > > > I've solved the control aspect, but not how to detect a pressure > > > > > to > > > > > accomplish the control. > > > > > > > > > > automotive EGR types seem seem the most promising as they are > > > > > affordable and 2 port gismo's but all I can find just lists the > > > > > vehicles it fits and works with, but zero info on how to hook it > > > > > up > > > > > and get an analog reading out of it. "MAP" sensors whose > > > > > internal > > > > > reference is a good vacumm can have their signals clipped and > > > > > massaged into something usable, but so far I've bought 4 w/o > > > > > finding > > > > > a working one that actually reads the 14.7 psia of normal air. > > > > > > > > > > So how are you folks solving that problem? > > > > > > > > > > Or are you burning up the shop compressor feeding your misters? I > > > > > can't see that as being an acceptible solution since none of > > > > > those > > > > > have an intake muffler so you can still hear yourself think. > > > > > > > > > > What I have cobbled up at the moment is giving me more than > > > > > enough > > > > > air to run a mister, and I can't hear it running over the 2 fans > > > > > in > > > > > this 6040 mill. One in the vfd is really noisy. > > > > > > > > > > Thank you. > > > > > > > > > > Cheers, Gene Heskett. > > > > > -- > > > > > > > > > > "There are four boxes to be used in defense of liberty: > > > > > soap, ballot, jury, and ammo. Please use in that order." > > > > > > > > > > -Ed Howdershelt (Author, 1940) > > > > > If we desire respect for the law, we must first make the law > > > > > respectable.> > > > > > > > > > > - Louis D. Brandeis > > > > > > > > > > _______________________________________________ > > > > > Emc-users mailing list > > > > > Emc-users@lists.sourceforge.net > > > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > Cheers, Gene Heskett. > > > -- > > > > > > "There are four boxes to be used in defense of liberty: > > > soap, ballot, jury, and ammo. Please use in that order." > > > > > > -Ed Howdershelt (Author, 1940) > > > If we desire respect for the law, we must first make the law > > > respectable.> > > > - Louis D. Brandeis > > > > > > _______________________________________________ > > > Emc-users mailing list > > > Emc-users@lists.sourceforge.net > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > Cheers, Gene Heskett. > -- > "There are four boxes to be used in defense of liberty: > soap, ballot, jury, and ammo. Please use in that order." > -Ed Howdershelt (Author, 1940) > If we desire respect for the law, we must first make the law respectable. > - Louis D. Brandeis > > > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
