| ??? 04/20/07 16:04 Read: times |
#137654 - Ambiguity? Responding to: ???'s previous message |
Naresh R said:
I have a great on ambiguity on Hardware connection for MMIO and Hardware Registers. IF you don't say what the "ambiguity" is, how can anybody explain it to you? "Memory-Mapped IO" means that the IO is accessed by the processor's standard memory access scheme; ie, via the Data and Address busses - as opposed to directly accessing the ports, or using some serial scheme, etc. On an 8051, this means using the MOVX instruction (or, for read-only, you could possibly use MOVC). Do you understand how the 8051's external memory accessing works? ie, how it uses the data & address busses and the other control lines (ALE, /PSEN, /RD, /WR)? If not, you need to study that first! It's in the so-called "bible" for the 8051 - chapter 3, start at p22; Also at the start of chapter 1: Chapter 1 - 80C51 Family Architecture: http://www.nxp.com/acrobat_d...ARCH_1.pdf Chapter 2 - 80C51 Family Programmer's Guide and Instruction Set: http://www.nxp.com/acrobat_d...UIDE_1.pdf Chapter 3 - 80C51 Family Hardware Description: http://www.nxp.com/acrobat_d...WARE_1.pdf Also take a look at the Tutorial on this site. |
