RTEMS 4.8.0 On-Line Library

Initialization Code Chip Select Initialization

BSP and Device Driver Development Guide

7.5: Chip Select Initialization

When the microprocessor accesses a memory area, address decoding is handled by an address decoder, so that the microprocessor knows which memory chip(s) to access. The following figure illustrates this:

                     +-------------------+
         ------------|                   |
         ------------|                   |------------
         ------------|      Address      |------------
         ------------|      Decoder      |------------
         ------------|                   |------------
         ------------|                   |
                     +-------------------+
           CPU Bus                           Chip Select

The Chip Select registers must be programmed such that they match the linkcmds settings. In the gen68340 BSP, ROM and RAM addresses can be found in both the linkcmds and initialization code, but this is not a great way to do this. It is better to define addresses in the linker script.

BSP and Device Driver Development Guide