| ??? 04/11/06 06:06 Read: times |
#114058 - which derivative Responding to: ???'s previous message |
hi,
Markus Kammersberger said:
i wondered about the movx instruction in combination with the addressing mode using R0 and R1. I want to store the value of the accumulator into external RAM. I know this works with "MOVX @DPTR,A", but what is the other instruction "MOVX @R0,A" for? In the instructionset i found this declaration: Which derivative do you use? You should read its datasheet. Otherwise you may come into troubles using "not classic" 8051 derivatives. Here are some troubles (may not exactly be about @Ri): - some derivatives use additional register to define high byte of 16-bit address for @Ri; - some derivatives allow to select which ports are used for MOVX; - some derivatives may use not multiplexed XRAM access; - some derivatives insert stretch cycles during MOVX; - some derivatives use external signal /WAIT for timing MOVX; - some derivatives have built-in extended RAM (which may have configurable size and/or address access window); - some derivatives have no external memory/program interface; - some derivatives do not allow to use MOVX with @Ri; - some derivatives use MOVX for 16-bit data access and so port 2 needs with data latch as well; - what else... Regards, Oleg |
| Topic | Author | Date |
| unclarity with movx instruction | 01/01/70 00:00 | |
| Speed up | 01/01/70 00:00 | |
| Mistake | 01/01/70 00:00 | |
| Clarity prevails! | 01/01/70 00:00 | |
| Quicker? | 01/01/70 00:00 | |
| Quicker! | 01/01/70 00:00 | |
| assumption... | 01/01/70 00:00 | |
| Finally, you are right! | 01/01/70 00:00 | |
| MOVX @Ri | 01/01/70 00:00 | |
| since you did not have the time to find | 01/01/70 00:00 | |
| wrong answer | 01/01/70 00:00 | |
| Typo | 01/01/70 00:00 | |
| thanks Erik for the correction | 01/01/70 00:00 | |
| It is set to P0 | 01/01/70 00:00 | |
| wrong again | 01/01/70 00:00 | |
| Yes I am | 01/01/70 00:00 | |
| an example | 01/01/70 00:00 | |
| Internal XRAM | 01/01/70 00:00 | |
| not really | 01/01/70 00:00 | |
| Ports' SFR are set to 1 | 01/01/70 00:00 | |
not a port, a "page SFR" | 01/01/70 00:00 | |
| P2? | 01/01/70 00:00 | |
| Doh! | 01/01/70 00:00 | |
| which derivative | 01/01/70 00:00 | |
| do not allow? | 01/01/70 00:00 | |
| AT89S8252 | 01/01/70 00:00 | |
| Aaaaah, so. Thanks. | 01/01/70 00:00 | |
| Tanks | 01/01/70 00:00 |