Subversion Repositories neorv32

<<<
:sectnums:
==== Bootloader ROM (BOOTROM)

[cols="<3,<3,<4"]
[frame="topbot",grid="none"]
|=======================
| Hardware source file(s): | neorv32_boot_rom.vhd | 
| Software driver file(s): | none             | _implicitly used_
| Top entity port:         | none             | 
| Configuration generics:  | _INT_BOOTLOADER_EN_ | implement processor-internal bootloader when _true_
| CPU interrupts:          | none             | 
|=======================

[NOTE]
The default `neorv32_boot_rom.vhd` HDL source file provides a _generic_ memory design that infers embedded
memory for _larger_ memory configurations. You might need to replace/modify the source file in order to use
platform-specific features (like advanced memory resources) or to improve technology mapping and/or timing.

This HDL modules provides a read-only memory that contain the executable code image of the bootloader.
If the <<_int_bootloader_en>> generic is _true_ this module will be implemented and the CPU boot address
is modified to directly execute the code from the bootloader ROM after reset.

The bootloader ROM is located at address `0xFFFF0000` and can occupy a address space of up to 32kB. The base
address as well as the maximum address space size are fixed and cannot (should not!) be modified as this
might address collision with other processor modules.

The bootloader memory is _read-only_ and is automatically initialized with the bootloader executable image
`rtl/core/neorv32_bootloader_image.vhd` during synthesis. The actual _physical_ size of the ROM is also
determined via synthesis and expanded to the next power of two. For example, if the bootloader code requires
10kB of storage, a ROM with 16kB will be generated. The maximum size must not exceed 32kB.

[NOTE]
Any write access to the BOOTROM will raise a _store access fault_ exception.

.Bootloader - Software
[TIP]
See section <<_bootloader>> for more information regarding the actual bootloader software/executable itself.

.Boot Configuration
[TIP]
See section <<_boot_configuration>> for more information regarding the processor's different boot scenarios.