On Mon, 5 Aug 2002 14:14:12 +0100 Cole Christopher J writes: > Afternoon all, > > I fear this is a very stupid question, sorry :) > > Sadly, my MAX488E chip isnt working with my PIC16C74A. I'm almost > certain the problem is something to do with internal pullup resistor > on the PortB input that the RO line from the Max488e is connected > to. The RO line into the PIC is never going high. > > Data transfer (PIC->Max488->Max488->PIC) works when RO from the > Max488 is connected to an input on PortA, without any pullup > resistor (although the input is then floating when it should be > low). > > Basically I can use PortB and get a proper 'low' state but an > invalid 'high' state, or use PortA and get the opposite. > > Should it be possible to wire up a Max488 directly to a PIC? (I > assumed it would be simply because the PCB I'm using has been > designed by someone who obviously thought you should be able to) If > this is not the right way to go about things, does anyone got a > simple circuit diagram showing how it should be done? > Yes, I use the MAX488 in all the Dove Systems DMX products. No problems! It should be able to drive a line high and low with or without a pull-up. I use them to drive hardware UARTs on port C of 18C452s, 18F452s, and 16F74s. Harold FCC Rules Online at http://hallikainen.com/FccRules Lighting control for theatre and television at http://www.dovesystems.com Reach broadcasters, engineers, manufacturers, compliance labs, and attorneys. Advertise at http://www.hallikainen.com/FccRules/ . ________________________________________________________________ GET INTERNET ACCESS FROM JUNO! Juno offers FREE or PREMIUM Internet access for less! Join Juno today! For your FREE software, visit: http://dl.www.juno.com/get/web/. -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads