| ??? 07/05/05 18:49 Read: times |
#96638 - register - RAM overlap Responding to: ???'s previous message |
Hi Jeroen,
maybe you are fooled by the 8051 specific behaviour that the registers in fact are RAM cells. Assuming that you use register bank 0, and this is what your code does, register R0 in fact is equal to RAM address 0, R1 is equal to 1, and so on. So what happens if the 8051 executes your code: FILL_MEM mov R0, #00h <- writes 0x00 into address 0x00 mov @R0, #'A' <- writes 0x41 into address 0x00 the data is ok but it overwrites your pointer in R0 inc R0 <- writex 0x42 into address 0x00 mov @R0, #'B' <- writex 0x42 into address 0x42 I'm sure that this isn't that what you wanted. So, do not use the RAM area starting at 0 for to store data. Registers are overlapped with the lower 32 Bytes of RAM. And don't forget to set the stack pointer to a valid address before you call a subroutine Hope that helps, Harald |
| Topic | Author | Date |
| how to use RAM? | 01/01/70 00:00 | |
| RAM | 01/01/70 00:00 | |
| Flaw | 01/01/70 00:00 | |
| why flaw? | 01/01/70 00:00 | |
| Register Banks Are Not in Bible :-o | 01/01/70 00:00 | |
| open up your eyes and let the sun shine | 01/01/70 00:00 | |
| Misunderstood | 01/01/70 00:00 | |
| If you want to state "wonder" SAY SO | 01/01/70 00:00 | |
| RAM area | 01/01/70 00:00 | |
| but how? | 01/01/70 00:00 | |
| Do it yourself | 01/01/70 00:00 | |
| I will do It myself | 01/01/70 00:00 | |
| upper RAM | 01/01/70 00:00 | |
| how can anyone help based on what you th | 01/01/70 00:00 | |
| register - RAM overlap | 01/01/70 00:00 | |
See Post By Andy below | 01/01/70 00:00 | |
| Not in the Tutorial?? :-0 | 01/01/70 00:00 |