ADSP-BF537 Blackfin Processor Hardware Reference
19-9
System Reset and Booting
is set, the
EVT1
register is not modified by the boot kernel on software
resets. Therefore, programs can control the reset vector for software resets
through the
EVT1
register.
Neither hardware nor the kernel initializes the
EVT1
register in no-boot
mode. Programs should initialize
EVT1
before issuing software resets in
no-boot environments.
Servicing Reset Interrupts
The processor services a reset event just like other interrupts. The reset
interrupt has top-priority. Only emulation events have higher priority.
When it comes out of reset, the processor is in supervisor mode and has
full access to all system resources. To enter the user mode, the reset service
routine must initialize the
RETI
register and terminate by an RTI instruc-
show the least
instructions required to handle the reset event. See the
ADSP-BF53x/BF56x Blackfin Processor Programming Reference for details
on user and supervisor modes.
Systems that do not work in an OS environment may not enter user
mode. Typically, the interrupt level needs to be degraded down to IVG15.
The following listing shows how this is accomplished.
Listing 19-2. Exiting Reset to User Mode
_reset:
P1.L = LO(_usercode) ; /* Point to start of user code */
P1.H = HI(_usercode) ;
RETI = P1 ; /* Load address of _start into RETI */
RTI ; /* Exit reset priority */
_reset.end:
_usercode: /* Place user code here */
...
Summary of Contents for Blackfin ADSP-BF537
Page 42: ...Contents xlii ADSP BF537 Blackfin Processor Hardware Reference ...
Page 90: ...Development Tools 1 32 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 138: ...Programming Examples 4 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 340: ...SDC Programming Examples 6 84 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 606: ...Programming Examples 9 94 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 660: ...Programming Examples 10 54 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 720: ...Electrical Specifications 11 60 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 840: ...Programming Examples 13 42 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 876: ...Programming Examples 14 36 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 938: ...Programming Examples 15 62 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 958: ...Programming Examples 17 12 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 986: ...Programming Examples 18 28 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 1162: ...G 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 1218: ...Index I 56 ADSP BF537 Blackfin Processor Hardware Reference ...