The safe way to do that is to use pullups on the four lines and only every set pins to output and low. Any lines that need to be high are left as inputs. So to put 0011 on the bus you would set the tris bits to output, output, input, input.
Sure, as long as only one PIC's TRIS register is set to output at a time. The code in each PIC will have to watch the respective "ChipEnable" input Pin, and then set its four output pins to output mode only as long as ChipEnable is high; when it goes low, it will have to set its four output pins to input mode.
Sure, as long as only one PIC's TRIS register is set to output at a time. The code in each PIC will have to watch the respective "ChipEnable" input Pin, and then set its four output pins to output mode only as long as ChipEnable is high; when it goes low, it will have to set its four output pins to input mode.
That's exactly what I'm going to do.The PIC outputs always set to INPUTs by the TRIS registers.It will turn the TRIS to OUTPUTS one at a time by the chip select pins.