SAMA5D27 datasheet(39/55 Pages) MICROCHIP

39 / 55 page

Booting Guidelines

This section provides an overview of how to program a Non-Volatile Memory (NVM) and boot from it.

The SAMA5D27 SOM1 embeds a Quad I/O Flash Memory as a source for boot. Another type of NVM may be

located on the motherboard. This section explains how to program, select and boot from an NVM.

7.1

Boot Process

The system always boots from the ROM memory at address 0x0. The ROM code is a boot program contained in the

embedded ROM. It is also called “First level bootloader”. The SAMA5D2 can be configured to run a Standard Boot

mode or a Secure Boot mode. More information on how the Secure Boot mode can be enabled, and how the chip

operates in this mode, is provided in the document SAMA5D2x Secure Boot Strategy. To obtain this application note

and additional information about the secure boot and related tools, contact a Microchip sales representative.

By default, the chip starts in Standard Boot Mode.

The ROM code standard sequence is executed as follows:

• Basic chip initialization: crystal or external clock frequency detection.

• Attempt to retrieve a valid code from external non-volatile memories (NVM).

• Execution of a monitor called SAM-BA® Monitor, in case no valid application has been found on any NVM (1).

Note:

This may be the case during the first start-up or after an NVM erase or when a "boot disable jumper" is used

on the memory Chip Select, in order to force an update.

7.2

Boot Configuration

The boot sequence is controlled using a Boot Configuration Word in the Fuse area or in the backup registers

BUREG.

For details, refer to the section “Boot Configuration” of the SAMA5D2 Data Sheet, document no. DS60001476.

7.3

NVM Programming

The SAMA5D27 SOM1 is delivered with SAM-BA® In-System Programmer, a comprehensive tool to program boot

memories.

In case the boot code does not find a valid program in NVM, the SAM-BA monitor is launched in order to program the

considered NVM.

The SAM-BA monitor principle is to:

• Initialize DBGU and USB.

• Check if USB Device enumeration occurred.

• Check if characters are received on the DBGU.

Once the communication interface is identified, the application runs in an infinite loop waiting for different commands.

The firmware can be sent and programmed in the NVM.

For more information, refer to the following link: www.at91.com/linux4sam/bin/view/Linux4SAM/

Sama5d2XplainedMainPage#Using_SAM_BA_to_flash_components.

7.4

Boot From External Memory

Several types of external memories such as NAND Flash, SDCard, SPI Flash, QSPI Flash, etc. can be connected to

the SAMA5D27 SOM1 and placed on the motherboard.

SAMA5D27 SOM1

Booting Guidelines

Datasheet

DS60001521D-page 39

SAMA5D27 датащи(PDF) 39 Page - Microchip Technology

SAMA5D27 датащи(HTML) 39 Page - Microchip Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55

датащи скачать

ссылки URL