Using Code Overlays from ROM on the ADSP-21161N EZ-KIT Lite Application Note

About this manual

Software overlays are useful for systems with tight memory constraints where adding external RAM is costly. This document addresses the obstacle of determining overlay locations in the ROM when standard linkers lack this support.

The guide details three main routines: locating overlay information by scanning the boot PROM, parsing collected data to determine section types and sizes, and managing the DMA process to import overlays into internal memory upon execution.

What's inside

• Introduction
• Locating Overlay Information
• Parsing of Collected Information
• Overlay Manager
• DMA Setup Process

Frequently asked questions

What problem do software overlays solve in systems with limited memory?

They provide a feasible solution when internal memory is limited and adding external RAM significantly increases cost.

What is the address range used for overlays defined in the memsdram section?

The linker generates an address in the range of 0x600000 to 0x6FFFFF for these overlays.

How many pieces of information are written into buffers when an overlay section is discovered?

Three pieces of information are written: the real live address, the section count size, and the section data or code type.