| ??? 01/17/05 16:31 Read: times |
#85110 - I think that... Responding to: ???'s previous message |
I think that what Mr. Botha was trying to ask about is if he could put the bit number for one of his three devices into a variable and then use that variable like an address source for the bit to the port pin.
Unfortunately this does not work as the 8052 instruction set does not support indirect bit addressing. Only direct bit addressing is allowed. This issue has come up recently where somebody was hoping for an @R0 addressing mode to a bit with the bit number in the R0 register. However such instruction does not exist. Leon's use of C language puts a slightly different light on the subject but the Keil C does not support an indirect BIT support mode either !! Michael Karas BTW.....If I get some time later today I'll write up a small subroutine that would give the equivalent behavior of an indirect bit function....but it uses a table and so takes more code space than a simple mask like Peter suggested or a If-ElseIf-ElseIf-ENdif structure to sort out which bit number to access. MJK |
| Topic | Author | Date |
| sbit | 01/01/70 00:00 | |
| I do not understand | 01/01/70 00:00 | |
| You mean Dallas 1-Wire? | 01/01/70 00:00 | |
| Re | 01/01/70 00:00 | |
| What's the problem? | 01/01/70 00:00 | |
| I think that... | 01/01/70 00:00 | |
| indirect bit addressing | 01/01/70 00:00 | |
| The same iButton on all 3? | 01/01/70 00:00 | |
| sbit | 01/01/70 00:00 | |
| access all 3 , one at a time | 01/01/70 00:00 | |
| I had the same problem | 01/01/70 00:00 | |
| Lets try again | 01/01/70 00:00 | |
| Need ? | 01/01/70 00:00 | |
| Why? | 01/01/70 00:00 | |
| There is always the switch statement | 01/01/70 00:00 | |
| something like this... | 01/01/70 00:00 | |
| Simultaneous example | 01/01/70 00:00 | |
| Use MASK rather than bit address | 01/01/70 00:00 | |
| Oooops, sorry... | 01/01/70 00:00 | |
| Multiple 1Wire | 01/01/70 00:00 | |
| How to post code, and possible hang-up | 01/01/70 00:00 | |
| simultaneous? | 01/01/70 00:00 | |
| would even be better | 01/01/70 00:00 | |
If it worked! | 01/01/70 00:00 |