When using the 8255 to glow an LED array using BSR mode, is it necessary to first set port c as an output port? Why?
In our lab, when I had not not set port C as output and directly used BSR mode to set and reset individual bits, only the 4 led's connected to the lower four bits of port C were responding. When I set port C as output, the desired output was obtained. But what is the need to set port C as output? When we are setting and resetting certain bits in port C, shouldn't port C automatically be taken as an output port?