Section number Title Page
7.2.5 SJC TAP Port...............................................................................................................................................278
7.2.6 SJC main blocks...........................................................................................................................................278
7.3 Miscellaneous............................................................................................................................................................... 279
7.3.1 Clock/Reset/Power.......................................................................................................................................279
7.4 Supported tools............................................................................................................................................................. 279
Chapter 8
System Boot
8.1 Chip-specific Boot Information.................................................................................................................................... 281
8.2 Overview.......................................................................................................................................................................284
8.3 Boot modes................................................................................................................................................................... 285
8.3.1 Boot mode pin settings.................................................................................................................................286
8.3.2 High-level boot sequence.............................................................................................................................286
8.3.3 Boot From Fuses mode (BOOT_MODE[1:0] = 00b)..................................................................................287
8.3.4 Serial Downloader (BOOT_MODE[1:0] = 01b)......................................................................................... 288
8.3.5 Internal Boot mode (BOOT_MODE[1:0] = 0b10)...................................................................................... 288
8.3.6 Boot security settings...................................................................................................................................289
8.4 Device configuration.....................................................................................................................................................290
8.4.1 Boot eFUSE descriptions.............................................................................................................................290
8.4.2 GPIO boot overrides.................................................................................................................................... 291
8.4.3 Device Configuration Data (DCD).............................................................................................................. 292
8.5 Device initialization......................................................................................................................................................292
8.5.1 Internal ROM/RAM memory map...............................................................................................................293
8.5.2 Boot block activation .................................................................................................................................. 293
8.5.3 Clocks at boot time...................................................................................................................................... 294
8.5.4 Enabling Caches...........................................................................................................................................296
8.5.5 Exception handling...................................................................................................................................... 296
8.5.6 Interrupt handling during boot..................................................................................................................... 297
8.5.7 Persistent bits............................................................................................................................................... 297
8.6 Boot devices (internal boot)..........................................................................................................................................297
i.MX RT1020 Processor Reference Manual, Rev. 0, 06/2018
NXP Semiconductors 5