AN 736: Nios II Processor Booting From Altera Serial Flash (EPCQ)

ID 683104
Date 5/20/2016
Public

1.3.1. Nios II Processor Application Execute-In-Place from EPCQ Flash

The execute-in-place option is suitable for Nios® II processor applications which require limited on-chip memory usage.

The alt_load() function operates as a mini boot copier which initializes and copies only the writable memory sections to on-chip RAM (OCRAM). The code section (.text), which is a read-only section, remains in the Intel® EPCQ flash memory region. Retaining the read-only section in EPCQ helps to minimize RAM use, but may limit the code execution performance. The Nios® II processor application is programmed into the EPCQ flash.

The Nios® II processor reset vector points to the EPCQ flash to allow code execution after the system resets. If you are debugging the application using the source-level debugger, you must use a hardware breakpoint because the EPCQ cannot efficiently support random memory access.