In message , "HOLDSTOCK S.M" writes >I'm a student at staffs Uni in my last year of a Elecronic >Eng Hons Degree. For my final year project, I'm interested >in designing a digital multimeter data aquistion device. > >Basically a device which will measure voltage and current, >probably using a PIC, and then download the >information (real-time) in Binary format via the RS232 >Serial port to a PC, where a WIN '95 application I'm >developing at the moment will tabulate all Data. I've been meaning to build something similar for a while now, but haven't got round to it yet!. I'm intending using a 16C84 with an external 12 bit ADC, something like an LTC1298 (I think that's the correct number). For the input side I'm planning using two channels, with scope type attenuators and opamps feeding into a cmos switch operated by an output from the PIC. Some of the LTC chips already have two inputs, that would obviate the need for the CMOS switch. So far I'm undecided wether to have the processor continually reading the inputs and sending the data back to a PC, or to have the PC request the data for the channel it wants to read. Using the second method requires two way RS232, the first way only requires one way. As it would be a good idea to opto-isolate the unit from the PC, it would make life easier just one way. On the other hand, with two way communication you could use the PIC to switch the input ranges from a nice on-screen meter/scope display. I'd be interested to see how your system develops. -- Nigel. /--------------------------------------------------------------\ | Nigel Goodwin | Internet : nigelg@lpilsley.demon.co.uk | | Lower Pilsley | Web Page : http://www.lpilsley.demon.co.uk | | Chesterfield | | | England | | \--------------------------------------------------------------/