SPRUIU1C July 2020 – February 2024 DRA821U , DRA821U-Q1
The MCU_BOOTMODE pins are sampled during both, MCU-Only and normal boot. The MCU_BOOTMODE pins are the only pins sampled during MCU-only boot mode, that is, BOOTMODE pins are not considered. MCU_BOOTMODE pin mapping is shown in Table 4-2.
MCU 9 | MCU 8 | MCU 7 | MCU 6 | MCU 5 | MCU 4 | MCU 3 | MCU 2 | MCU 1 | MCU 0 |
POST Config(1) | OVRD(2) | MCU Only | Primary Boot Mode A | PLL Config |
Table 4-3 describes the MCU_BOOTMODE pins that need to be set according to the system clock provided to the device.
The ROM Code will configure any PLLs required during the boot process. The ROM Code does not have the ability to select HFOSC1 (in main domain) during initial boot, however the selection can be done through the boot certificate (see Section 4.5, Boot Image Format).
PLL Config Pins | Ref Clock (MHz) | ||
---|---|---|---|
MCU 2 | MCU 1 | MCU 0 | |
0 | 0 | 0 | 19.2 |
0 | 0 | 1 | 20 |
0 | 1 | 0 | 24 |
0 | 1 | 1 | 25 |
1 | 0 | 0 | 26 |
1 | 0 | 1 | 27 |
1 | 1 | 0 | Reserved |
1 | 1 | 1 | No PLL setup(1) |
If MCU Only mode (boot from MCU domain only) needs to be selected, the MCU Only pin must be set to 1 (see Table 4-4).
MCU Only Pin | MCU Only Selection |
---|---|
MCU 6 | |
0 | Normal boot mode. Both MCU_BOOTMODE and BOOTMODE pins are read by ROM code |
1 | MCU Only boot mode. Boot can proceed only from MCU peripherals |
Power-On Self-Test sequence is executed as directed by pins shown in Table 4-5. Dedicated eFuse bits may override the POST pins. See register CTRLMMR_WKUP_POST_OPT in section WKUP_CTRL_MMR0 Registers and POST section in the Safety Manual for details.
POST Config Pins | POST Sequence | |
---|---|---|
MCU 9 | MCU 8 | |
0 | 0 | DMSC LBIST followed by MCU LBIST followed by PBIST(2) |
0 | 1 | DMSC LBIST and MCU LBIST in parallel followed by PBIST(2) |
1 | 0 | DMSC LBISTReserved(2) |
1 | 1 | POST bypass(1) |
Table 4-6 lists the boot modes (both primary and backup), available when MCU Only boot was selected. For normal boot modes, refer to Table 4-8 and Table 4-9
Primary Boot Mode A Pins | Primary Boot Mode Selected | Backup Boot Mode Assigned(1) | ||
---|---|---|---|---|
MCU 5 | MCU 4 | MCU 3 | ||
0 | 0 | 0 | Hyperflash | UART |
0 | 0 | 1 | OSPI | UART |
0 | 1 | 0 | QSPI | UART |
0 | 1 | 1 | SPI | UART |
1 | 0 | 0 | Ethernet RGMII | I2C |
1 | 0 | 1 | Ethernet RMII | I2C |
1 | 1 | 0 | I2C | UART |
1 | 1 | 1 | UART | I2C |