MPU Interface
3-33
DSP Subsystem
3.6
MPU Interface
The MPU interface (MPUI) is a 16-bit parallel port that allows the MPU and the
system DMA controller to communicate with the DSP and its peripherals, facili-
tating software downloads and data transfers. The MPUI provides the MPU
with access to the full memory space of the DSP (16M bytes). In addition, the
MPUI allows the MPU to access devices on the DSP public peripheral bus
through duplicate memory-mapped peripheral registers in the MPU address
space. The MPU domain may also access the control registers of the TIPB
bridge module and the CLKM2 configuration registers. The DSP private
peripherals are not accessible via the MPUI.
MPUI transfers are facilitated by an auxiliary channel of the DSP subsystem
DMA controller; however, this dedicated DMA channel is preconfigured and
need not need to be user-configured for MPUI support.
The MPU domain (including TI925T and system DMA) always masters the
transfer operation. It initiates the read or write of DSP memory or peripherals.
The MPU also controls the parameters of the MPUI by configuring the
MPUI_CTRL_REG and the MPUI_DSP_MPUI_CONFIG register. There are
5 additional registers the MPU can read to observe the state of the MPUI:
-
MPUI_DEBUG_ADDR
-
MPUI_DEBUG_DATA
-
MPUI_DEBUG_FLAG
-
MPUI_STATUS_REG
-
MPUI_DSP_STATUS_REG
The MPUI port supports four access modes:
-
Single-access mode, memory (SAM_M): SARAM, DARAM and, external
memory interface are shared between the DSP domain and the MPU
domain.
-
Single-access mode, peripheral (SAM_P): DSP public peripheral bus is
shared between the DSP domain and the MPU domain.
-
Host-only mode, memory (HOM_M): MPU has exclusive access to DSP
SARAM, but it cannot access other DSP memory resources.
-
Host-only mode, peripheral (HOM_P): MPU has exclusive access to the
DSP public peripheral bus.
SAM is the normal operating mode in which all the DSP internal memory and
the public peripherals are accessible by the MPUI interface as well as the DSP.
If both the DSP and the MPU controllers (TI925T and/or system DMA) access