ADSP-BF535 Blackfin Processor Hardware Reference
6-85
Memory
All MMRs are accessible only in Supervisor mode. Access to MMRs in
User mode generates an Illegal Access exception.
All core MMRs are read and written using 32-bit-aligned accesses. How-
ever, some MMRs have fewer than 32 bits defined. In this case, the
unused bits are reserved.
Accesses to nonexistent MMRs generate an exception. The system ignores
writes to read-only MMRs.
Appendix A provides a summary of all Core MMRs. Appendix B provides
a summary of all System MMRs.
To ensure upward compatibility with future implementations,
write back the value that is read for reserved bits in a register.
Core MMR Programming Code Example
Core MMRs may be accessed only as aligned 32-bit words. Non-aligned
access to MMRs generates an exception event.
Listing 6-5
shows the
instructions required to manipulate a generic core MMR.
Listing 6-5. Core MMR Programming
CLI R0; /* stop interrupts and save IMASK */
P0 = MMR_BASE; /* 32-bit instruction to loadbase of MMRs */
R1 = [P0 + TIMER_CONTROL_REG]; /* get value of control reg */
BITSET R1, #N; /* set bit N */
[P0 + TIMER_CONTROL_REG] = R1; /* restore control reg */
CSYNC; /* assures that the control reg is written */
STI R0; /* enable interrupts */
In the code listing, CLI saves the contents of the
IMASK
register and dis-
ables interrupts by clearing
IMASK
, while
STI
restores the contents of the
IMASK
register, thus enabling interrupts. The instructions between
CLI
and
STI
are not interruptible.
Содержание ADSP-BF535 Blackfin
Страница 80: ...Development Tools 1 26 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 312: ...Working With Memory 6 86 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 332: ...System Interfaces 7 20 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 360: ...Dynamic Power Management Controller 8 28 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 446: ...Beginning and Ending an SPI Transfer 10 40 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 522: ...Timing Examples 11 76 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 562: ...IrDA Support 12 40 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 608: ...PCI I O Issues 13 46 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 672: ...References 14 64 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 810: ...SDRAM Controller SDC 18 86 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 811: ...ADSP BF535 Blackfin Processor Hardware Reference 18 87 External Bus Interface Unit...
Страница 812: ...SDRAM Controller SDC 18 88 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 860: ...DMA Bus Debug Registers 20 30 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 908: ...SDRAM Controller External Bus Interface Unit B 36 ADSP BF535 Blackfin Processor Hardware Reference...