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The Kinetis Bootloader’s main task is to provision the internal flash memory with an
embedded firmware image during manufacturing, or at any time during the life of the
Kinetis device. The Kinetis Bootloader does the provisioning by acting as a slave device,
and listening to various peripheral ports where a master can start communication.
For the Kinetis device, the Kinetis Bootloader can interface with USB, I2C, SPI, and
LPUART peripherals in slave mode and respond to the commands sent by a master (or
host) communicating on one of those ports. The host/master can be a firmware-download
application running on a PC or an embedded host communicating with the Kinetis
Bootloader. Regardless of the host/master (PC or embedded host), the Kinetis Bootloader
always uses a command protocol to communicate with that host/master. Commands are
provided to write to memory (internal flash or RAM), erase flash, and get/set bootloader
options and property values. The host application can query the set of available
commands.
On start-up, the bootloader reads optional configuration parameters from a fixed area on
flash called the bootloader configuration area (BCA). These parameters can be modified
by the write memory command or by downloaded flash image. BCA parameters include
configuration data such as enabled peripherals, peripheral-specific settings, etc.
This chapter describes Kinetis Bootloader features, functionality, command structure and
which peripherals are supported.
Features supported by the Kinetis Bootloader in Kinetis ROM:
• Supports USB, I2C, SPI, and LPUART peripheral interfaces
• Automatic detection of the active peripheral
• Ability to disable any peripheral
• LPUART peripheral implements autobaud
• Common packet-based protocol for all peripherals
• Packet error detection and retransmission
• Flash-resident configuration options
• Fully supports internal flash security, including ability to mass erase or unlock
security via the backdoor key
• Protection of RAM used by the bootloader while it is running
• Provides command to read properties of the device, such as flash and RAM size
• Multiple options for executing the bootloader either at system start-up or under
application control at runtime
Introduction
KL27 Sub-Family Reference Manual , Rev. 5, 01/2016
174
Freescale Semiconductor, Inc.