Since each LED on the bargraph is individually accessable (ie, both anode and cathode are separate from the other LED anodes and cathodes) then you can easily implement a multiplexing or charlieplexing scheme. So you could drive 10 LEDs with 6 pins from the PIC: 1 pin goes to four of the LED cathodes (row 1) 1 pin goes to the other four led cathodes (row 2) 4 pins go to two anodes each (columns 1 through 4) If you bring row 1 low, row two as input, then you can light any of the four LEDs on row one by bringing any of the columns high. Then switch row 1 to input, bring low 2 low output, and do the same. Swithc back and forth more than 30 times per second and users will see all the LEDs being operated at once. Charlieplexing is a bit more complicated, but allows you to control 20 LEDs from 5 pins, or 12 LEDs from 4 pins, etc: http://www.instructables.com/id/ED0NCY0UVWEP287ISO/?ALLSTEPS -Adam On 4/19/07, Edward King wrote: > Hi! > > This is my first post, so hello to everyone on the list... > > I need to run a bargraph display from a PIC (exact type to be decided, but I have a range of 16F and a couple of 18F devices lying around). > The trouble is that due to space constraints, Im not really able to squeeze a 40 pin device in to the assembly and I dont have many GPIO lines left over... > > So my intention was to use a serial to parallel shift register to give me the required outs from a couple of pins. Trouble is that it seems only 8 bit SRs are common now (and the level meters / bargraph displays are all 10 part) so I was wondering how other people have done this. > > I tried looking through the archives, but I couldnt find anything where the designer has adopted this approach. > > EK > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Moving in southeast Michigan? Buy my house: http://ubasics.com/house/ Interested in electronics? Check out the projects at http://ubasics.com Building your own house? Check out http://ubasics.com/home/ -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist