On Thursday 09 August 2018 22:02:01 Mark Johnsen wrote: > > The parport emulator is available, but why tie up 90% of the gpio, > > when it can be done faster with just 4 wires? > > You have a point, but there's probably more paraport BOB's available > than the 4 wires spi boards. Probably less $$ for a simple paraport > BOB. > > But, I do like the SPI 4 wire solution, is pretty slick. > > Mark
Note that I am usually referring to the gpio available from the likes of a mesa 7i90HD interface card, not the 4 that are used to implement the spi on the pi itself. The 7i90HD is about $70, and gives you up to 72 gpio's. But its a fpga, and can be destroyed by motor switcher noises and such that exceed 3.4 volts. Its output is on 50 pin scsi like connectors, which aren't the handiest way to connect it to the real world, so there is also the 7i42TA, a bit over $40/copy, designed to protect the 7i90 from that sort of destructive noise, and gives you a couple rows of the green screw terminal strips to plug your wires to the real world into, and you then need only to make up the short 50 pin cables to jumper from the 7i90HD to the 7i42TA's. My 26 wire cable from the pi to the 7i90 is maybe 1.5" long, achieved by turning the pi upside down, removing the 180 degree twist in the cable at the same time. The 50 pin cables are 3 to 6" long and I have the 7i42TA'S stair-step stacked on top of the 7i90HD. The write speed of a 32 bit packet from the pi to the 7i90HD is 42 megabaud, and the data coming back is read at 25 megabaud. So I think that rather handily beats the parports speed while using only 3 pins and grounds on the pi's long connector. Doing a parport right on the pi will use just about every gpio it has. Firmware for the 7i90HD can be run from a parport, or the spi, you just have to program it with the right *.BIT file. I keep an old slow Dell around just to program mesa cards with mesaflash. It doesn't run on arm's (yet). > ---------------------------------------------------------------------- >-------- Check out the vibrant tech community on one of the world's > most engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > 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) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
