| ??? 02/19/08 02:50 Read: times Msg Score: +1 +1 Good Answer/Helpful |
#151092 - Value, not SFR address Responding to: ???'s previous message |
anl CFG831,#0BFh Brian Reid said:
I have been beating my little head against the wall trying to figure out how you came up with "#0BFh" to set the CFG831.6 bit to zero but I can't seem to figure it out. According to the info I have, the SFR address for CFG831 is AFh. Wouldn't bit 1 of the CFG831 SFR be BFh as opposed to bit 6? The address of the CFG831 SFR is AFh. It is not bit-addressable which means there is no way to access individual bits directly. You must access it on an SFR-wide basis. The quoted example is the same as ANL 0AFh,#0BFh. That instruction will take the value currently in SFR address 0AFh (which is CFG831) and AND it with the value 0BFh. 0BFh is the binary equivalent of 1011 1111 which has every bit set except bit 6. So when you AND BFh with the contents of CFG831, it will effectively clear bit 6 and leave all other bits in their original state. Regards, Craig Steiner |
