Embedded-Hacking/RA-0x0001-GPIO-Output/image_def.s

/**
 * FILE: image_def.s
 *
 * DESCRIPTION:
 * RP2350 IMAGE_DEF Block.
 * 
 * BRIEF:
 * A minimum amount of metadata (a valid IMAGE_DEF block) must be embedded in any
 * binary for the bootrom to recognise it as a valid program image, as opposed to,
 * for example, blank flash contents or a disconnected flash device. This must
 * appear within the first 4 kB of a flash image, or anywhere in a RAM or OTP image.
 * Unlike RP2040, there is no requirement for flash binaries to have a checksummed
 * "boot2" flash setup function at flash address 0. The RP2350 bootrom performs a
 * simple best‑effort XIP setup during flash scanning, and a flash‑resident program
 * can continue executing in this state, or can choose to reconfigure the QSPI
 * interface at a later time for best performance.
 *
 * AUTHOR: Kevin Thomas
 * CREATION DATE: October 5, 2025
 * UPDATE DATE: October 5, 2025
 */

.section .picobin_block, "a"                     // place IMAGE_DEF block in flash

.word  0xFFFFDED3                                // PICOBIN_BLOCK_MARKER_START
.byte  0x42                                      // PICOBIN_BLOCK_ITEM_1BS_IMAGE_TYPE
.byte  0x1                                       // item is 1 word in size
.hword 0b0001000000100001                        // SECURE mode (0x1021)
.byte  0xFF                                      // PICOBIN_BLOCK_ITEM_2BS_LAST
.hword 0x0001                                    // item is 1 word in size
.byte  0x0                                       // pad
.word  0x0                                       // relative pointer to next block (0 = loop to self)
.word  0xAB123579                                // PICOBIN_BLOCK_MARKER_END