On Saturday 21 November 2020 03:40:08 andrew beck wrote: > ok just did some testing > > when I flash the 5i25 with this 5i25_7i76x2.bit file it all works fine > > this is just with the 7i76 connected up > > when I try to connect up the 7i77 and flash this bit file > (5i25_7i76_7i77.bit) into the 5i25 I get a issue > > the 7i77 is coming up with a red led though in CR16 I read in the > manual that this goes red when there is a communication error with > 5i25. > > now I have just discovered that I powered the 7i77 with 5v and had the > polarity wrong so was trying to send -5v into 7i77. I may have > stuffed it I suppose. all the jumpered are set correctly but I may > have created a problem for myself
I think it may have some protection against reversed polarity, but don't quote me. The minus sign on lots of dvms gets hard to see when the window gets scratched up. I've not knowingly tested that. Read the pdf docs from Mesa, it should be noted if it has some reverse protection. > any thoughts or ideas sing out. > > I have another brand new 7i77 I will try now and just see if that one > works. Good idea, you can test it for sseriel com without having to hook up any i/o, just the cable from the5i25 and if not powering from the 5i25, the +5 volts. Its why I buy 3 cards if I'm going to use two. My wiring practices haven't always been as neat as they should be. While working on the contact holefinder, I was bitching, on this list, about the epoxy paint making very iffy grounds, but I found the heavy braided strap that supposedly grounds the frame of the 6040 to the electrical ground bar, didn't quite reach the ground bar. It had come unplugged from the tunnel type screw terminal and was just laying there about 2" away. That was all built while standing on the top step of a 4 foot stepladder as all its electrics are on a 2x4 shelf hanging from the ceiling on plumbers friend above the 6040. And nobody my age, 86, has any business that far up on a ladder. That is what folks keep telling me, for my own safety of course. :) With the shack gone, I've been reduced to making simple boards on the milling machine. That works, but tends not to be adequately documented by me, leading to what the heck was I doing there? questions 2 or 3 years later. The little one power v-fet board that runs the mister pump on the 6040 is one such example. :) > the existing 7i77 worked last week when I was testing which is why I > didn't double check wiring lol > > On Sat, Nov 21, 2020 at 9:23 PM Gene Heskett <ghesk...@shentel.net> wrote: > > On Saturday 21 November 2020 02:17:55 andrew beck wrote: > > > I have two plugs connected from 5i25 > > > > > > The cable to the 7i77 is a known good cable that was working last > > > week. If its a ribbon cable, that doesn't mean squat. Failure IS an option. And way too many designers forget to treat it as a transmission line. Improperly terminated, anything over a foot ought to be terminated in 125 or so ohms or it rings like the liberty bell. The theoretical impedance is about 132 ohms for such cabling. [...] Cheers Andrew, 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) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
