lance@helios.ucsc.edu (Lance Bresee) (09/28/90)
I am having trouble hooking up an 8049 to a 2764 EPROM. I hooked up a 74373 latch with latch and 'OE tied directly to ALE, and the 'CE and 'OE of the 2764 hooked to 'PSEN. The program should alternately output 00h and FFh on port 1, with a significant delay. The output of port one is connected directly to led's. Does anyone out there have any schematics of a known working, simple, 8048 device that I can look at? Thanx muchly lance%helios@ucscc.ucsc.edu
fayne@tellabs.com (Jeffrey Fayne) (10/03/90)
In article <7266@darkstar.ucsc.edu> lance@helios.ucsc.edu (Lance Bresee) writes: > >I am having trouble hooking up >an 8049 to a 2764 EPROM. I hooked >up a 74373 latch with latch and 'OE >tied directly to ALE, and the 'CE and 'OE >of the 2764 hooked to 'PSEN. The program >should alternately output 00h and FFh on >port 1, with a significant delay. The output >of port one is connected directly to led's. > >Does anyone out there have any schematics >of a known working, simple, 8048 device >that I can look at? > >Thanx muchly >lance%helios@ucscc.ucsc.edu As you aren't too specific on what exactly the problem is, I am assuming that you've debugged your program 'on-the-bench' and the logic looks right but when you burn an EPROM and power your system up it just sits there. Your EPROM hook up sounds right except, did you bring the EA pin (External access, pin 7) high (tie to Vcc) ? Without this pin wired high the 8048 will be executing internal ROM code, not your EPROM code. Also check that the RESET line is asserted high (a simple RC circuit is all that is needed). Good references to 8048 'projects' are Intel Databooks, BYTE circuit Cellar projects and Circuit Cellar Ink magazine. - Jeff -- _____________________________________________________________________________ F-14 | _ | | Jeffrey M. Fayne Tomcat | /^ ^\ | | Tellabs, Inc. Lisle, IL 60532 ____________|_( . )_|____________ | 708-512-7726 FAX:708-852-7346 --*/--|_| (___) |_|--\*-- | fayne@tellabs.com * O O * fjs | #include<StdDisclaimer.h> _____________________________________________________________________________