www.ti.com
2.9
Bootloader Modes
Bootloader Modes
To accommodate different system requirements, the boot ROM offers a variety of different boot modes.
This section describes the different boot modes and gives brief summary of their functional operation. The
states of three GPIO pins are used to determine the desired boot mode as shown in
.
Table 2-2. Boot Mode Selection
Mode
Description
GPIO18
GPIO29
GPIO34
SPICLKA
(1)
SCITXDA
SCITXDB
Boot to Flash
(2)
Jump to flash address 0x3F 7FF6. You must have programmed
1
1
1
a branch instruction here prior to reset to redirect code
execution as desired.
SCI-A Boot
Load a data stream from SCI-A.
1
1
0
SPI-A Boot
Load from an external serial SPI EEPROM on SPI-A.
1
0
1
I
2
C Boot
Load data from an external EEPROM at address 0x50 on the
1
0
0
I
2
C bus.
eCAN-A Boot
(3)
Call CAN_Boot to load from eCAN-A mailbox 1.
0
1
1
Boot to M0 SARAM
(4)
Jump to M0 SARAM address 0x00 0000.
0
1
0
Boot to OTP
(4)
Jump to OTP address 0x3D 7800.
0
0
1
Parallel I/O Boot
Load data from GPIO0 - GPIO15.
0
0
0
(1)
You must take extra care because of any effect toggling SPICLKA to select a boot mode may have on external logic.
(2)
When booting directly to flash, it is assumed that you have previously programmed a branch statement at 0x3F 7FF6 to redirect
program flow as desired.
(3)
On devices that do not have an eCAN-A module this configuration is reserved. If it is selected, then the eCAN-A bootloader will
run and will loop forever waiting for an incoming message.
(4)
When booting directly to OTP or M0 SARAM, it is assumed that you have previously programmed or loaded code starting at the
entry point location.
SPRU722C – November 2004 – Revised October 2006
Bootloader Features
21