TC1796
System Units (Vol. 1 of 2)
Reset and Boot Operation
User’s Manual 4-17 V2.0, 2007-07
Reset, V2.0
During the startup procedure, the NMI interrupt, the watchdog timer, and the debug
interfaces are disabled. The NMI interrupt has to be enabled by the user software
(SCU_CON.NMIEN bit set) after proper setup of the interrupt vector table.
The reset configuration indicated in register RST_SR is evaluated by the startup
procedure for selection of the configured operation and of program start memory.
Bootstrap Loader
The Bootstrap loader (BSL) is a software part of the Boot ROM which provides a
mechanism to load a program code into the Scratchpad RAM (SPRAM) of the PMI. The
program code to be loaded is received serially either via the ASC0 or CAN interfaces.
After loading of the code, the bootstrap loader jumps directly to address D400 0000
H
(start address of SPRAM) and begins executing the program code that has been loaded.
Further details about the BSL are described in Section 4.4.
Alternate Boot Modes
The alternate boot modes will only branch to an user program in PFLASH or external
code memory if a CRC checksum test shows no error. If the CRC check fails, a bootstrap
loader mode is entered instead of user program execution.
Tuning Protection
Tuning protection is supported to protect user software in external Flash memory from
being manipulated and to safely detect changes of this user software.
Emulation Support
If the device currently used is an emulation device (TC1796ED), a boot capability from
emulation memory is supported. For the standard TC1796 this boot option cannot be
activated.
Test and Stress Routines
The 8 Kbyte TestROM is reserved for special routines, which are used for testing,
stressing and qualification of the component. This boot option should never be activated
by a user program.
Boot ROM Program Flow
Figure 4-1 shows the basic Boot ROM program flow. This flow diagram has one input
(reset address DFFF FFFC
H
) and several outputs that depend on the selected boot
option (as described in Table 4-3).
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