System Operating Details
3-41
DSP Subsystem
3.10.4.1
Boot Modes
The DSP is reset by two signals:
-
nRESET is a global reset (active low) that resets the DSP subsystem ex-
cept for the TIPB interrupt priority encoder, the DSP EMIF configuration
registers, and the MPUI port control logic.
-
nMCURESET is a reset signal driven by the MPU (active low). It sets
the TIPB interrupt priority encoder registers, configures the DSP-EMIF
registers, and resets the MPUI control logic
The MPU controls these reset signals by writing into the RSTCT1 clock and
reset module register (see Chapter 15, Clock Generation and System Reset
Management).
There are five boot modes for the DSP subsystem. The MPU can select any
of these boot modes by the MPU by writing to the DSP_BOOT_CONFIG regis-
ter. When the DSP subsystem is released from reset (boot), the CPU always
fetches instruction at address 0xFFFF00. The physical location of this address
depends on the value of BOOT_MOD[3:0] bits.
If BOOT_MOD[3:0] is equal to 0000, the on-chip ROM is not available and the
boot address is located off-chip. If BOOT_MOD[3:0] is not equal to 0000, the
on-chip ROM is enabled and the boot address is located at the on-chip ROM.
The boot modes supported are listed in Table 3–13.
Table 3–13. Boot Modes
BOOT_MOD[3–0]
Boot Process
Starting Address of DSP MPU
0000
No boot download
0xFFFF00 (direct boot from a 32-bit asynchronous
interface)
0001
No boot download
Pseudodirect boot from a 32-bit asynchronous
interface (bootloader configures the EMIF, then
branches to address 0x080000)
0010
Put DSP into IDLE state
DSP is put into idle mode.
0011
16-bit boot download
Download code from 0x80000 to user specified
address (residing at address 0x080004 as 16-bit
data).
0100
32-bit boot download
Download code from 0x80000 to user specified
address (residing at address 0x080004 as 32-bit
data).
0101
MPUI boot download
Branch to address 0x10000
Other
Internal boot
Branch to address 0x24000
Note:
The DSP bootloader checks the BOOT_MOD[3:0] bits only once upon DPS subsystem release from reset.