In addition, the first 6 locations of the PIE vector table are used by the boot ROM. These locations are not used
by the PIE itself and are not used by typical applications. These locations are used as SARAM by the boot ROM
and do not effect the behavior of the PIE.
Note:
Some example code from previous devices may initialize these
locations. This will overwrite any boot mode you have populated. These locations are:
Table 2-3. PIE Vector SARAM Locations Used by the Boot ROM
Location
Name
Note
0x0D00 x 16
EMU_KEY
Used for emulation boot
0x0D01 x 16
EMU_BMODE
Used for emulation boot
0x0D02 x 32
Flash_CallbackPtr
Used by the flash API
0x0D04 x 32
Flash_CPUScaleFactor
Used by the flash API
2.2.9 Bootloader Modes
To accommodate different system requirements, the boot ROM offers a variety of boot modes. This section
describes the different boot modes and gives brief summary of their functional operation. The states of TRST
and two GPIO pins are used to determine the desired boot mode as shown in
Table 2-4. Boot Mode Selection
GPIO37 TDO
GPIO34
CMP2OUT
TRST
Mode EMU
x
x
1
Emulation Boot
Mode 0
0
0
0
Parallel I/O
Mode 1
0
1
0
SCI
Mode 2
1
0
0
Wait
Mode 3
1
1
0
GetMode
Note
The default behavior of the GetMode option on unprogrammed devices is to boot to flash. This
behavior can be changed by programming two locations in the OTP as shown in
if these locations are used by an application, then GetMode will jump to flash as long as OTP_KEY !
=0x005A and/or OTP_BMODE is not a valid value.
This device does not support the hardware wait-in-reset mode that is available on other C2000 parts.
The "wait" boot mode can be used to emulate a wait-in-reset mode. The "wait" mode is very important
for debugging devices with the CSM password programmed (that is, secured). When the device is
powered up, the CPU will start running and may execute an instruction that performs an access to a
protected emulation code security logic (ECSL) area. If this happens, the ECSL will trip and cause the
debug connection to be cut. The "wait" mode keeps this from happening by looping within the boot
ROM until the debug probe is connected.
shows an overview of the boot process. Each step is described in greater detail in following sections.
While each sub-section gives details regarding the implementation of the native boot modes on the device, they
do not address utilizing each boot mode for common system operations such as:
• Device Firmware Upgrade (DFU)
• Erasing the flash memory
• Verifying the flash memory
• Unlocking the security zones
• Running the embedded code from "main"
• Resetting the MCU
These operations and more are covered in the
Serial Flash Programming of C2000™ Microcontrollers
.
Boot ROM
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
TMS320x2806x Microcontrollers
205
Copyright © 2022 Texas Instruments Incorporated
Содержание TMS320 2806 Series
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