I try to make a clock on 8048 kit, with the enclosed PIC 16f627. Since I need 4 pins for output (i use a bcd to 7 segment decoder to drive the led display) and 4 bits for multiplexing, i try to use all pins of the port b. Unfortunately, portb,6 and portb,7 seem to be always on - the display looks weird (a randomly sparkling at the corresponding digits, although the application runs fine on simulator and also i can get on those digits something like a response when pressing the adjusting buttons (some segments look a little more bright). I look at the schematic of the project and i see that there are some resistors pulling up those pins (from the programing part of the board), but even after i remove those resistors, i don’t get any improvements.
So, i want to know if any of you run into the same problem trying to use all pins of the port b, and if so, what is the remedy. I think i should try a stand-alone version of the project, but i am afraid that the pcb is to difficult to manufacture.
Any sugestion/help wold be higly appreciated. Thanks!