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 On Sat, May 28, 2022 at 10:33 PM gene heskett <[email protected]> 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-hooku > > 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 <[email protected]> > 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 > > > [email protected] > > > 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 > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
