| ??? 05/05/08 02:50 Read: times |
#154398 - Another example of R-M-W Responding to: ???'s previous message |
Suppose you are using P3.0 as an output and P3.1 as an input. You would initialize P3.1 with a "1". You might also use the SETB and CLR instructions to manipulate P3.0.
If the R-M-W instruction read the port instead of the latch, and if the input data on P3.1 was a "0", then the R-M-W instruction would write a "0" back to P3.1. And that would prevent P3.1 from ever bewing a "1". Reading the latch is the only way to make the instruction work. |
| Topic | Author | Date |
| why diff. method to read 9051 port | 01/01/70 00:00 | |
| because .... | 01/01/70 00:00 | |
Another example of R-M-W | 01/01/70 00:00 |