ONDA SOM/ONDA Hardware/Power and Reset/System boot
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System boot[edit | edit source]
In order to fully understand how boot works on the ONDA SOM, please refer to Chapter 11 ("Boot and configuration") of the Zynq UltraScale+ Device Technical Reference Manual (UG1085).
The BootROM can boot the system from Quad-SPI, SD, eMMC, USB 2.0 controller 0, or NAND external boot devices. All modes can be non-secure or be secure and signed except PS JTAG and PJTAG.
The system boot-up process is managed and carried out by the platform management unit (PMU) and configuration security unit (CSU). The boot-up process consists of three functional stages.
- Pre-configuration stage
- Configuration stage
- Post-configuration stage
The PMU performs a number of mandatory and optional security operation, the CSU is the central configuration processor that manages secure and non-secure system-level configuration.
After a system reset, the system automatically sequences to initialize the system and process the first stage boot loader from the selected external boot device.
Boot options[edit | edit source]
The boot ROM supports configuration from different slave interfaces, but not all of them are available in the ONDA SOM. Here below the list of available boot interface:
- PS JTAG
- onboard QSPI 32 bit NOR flash(es)
- SD1
- onboard eMMC
- USB
Boot mode is selectable via mode pins (PS_MODE[3:0]); here below the allowed boot modes
| Boot interface | BOOT_MODE[3..0] | Pin location |
|---|---|---|
| PS JTAG | 0000 | JTAG |
| QPSI 32 bit | 0010 | MIO[12:00] |
| SD1 | 0101 | MIO[51:43] |
| eMMC | 0110 | MIO[22:13] |
| USB | 0111 | MIO[63:52] |
Default boot configuration for ONDA SOM is PS_MODE[3:0] = 0010 (QSPI 32-bit)
Boot sequence customization[edit | edit source]
PS_MODE[3:0] are routed to the J1 connector, enabling for the customization of the boot sequence through a simple resistor network that can be implemented on the carrier board hosting the ONDA SOM.
| Mode signal | J1 pin | Notes |
|---|---|---|
| PS_MODE[3] | J1.125 | - |
| PS_MODE[2] | J1.121 | - |
| PS_MODE[1] | J1.123 | - |
| PS_MODE[0] | J1.119 | - |
