TIPB Bridge
3-29
DSP Subsystem
3.5.1
Control Mode Register (CMR)
The CMR indicates shared access mode/host-only mode (SAM/HOM) status
of the MPUI and bus error condition status for accesses to the TIPB bridge.
It also controls CPU priority versus the MPUI and DMA for accesses to
peripherals on the TIPB bridge.
Table 3–7. Control Mode Register (CMR) – Value at Reset is 0xFE4D
CMR
[15–0]
Designation
Description
Reset
Value
CPU Access
MPU Access
15–9
Time-out (6:0)
Strobe cycles
(0-127)
0x7F
Read/Write
Read
8–6
Wait state
(strobe2)
Strobe1 length
(low, medium, high
bits)
0
Read/Write
Read
5–3
Wait state
(strobe1)
Strobe1 length
(low, medium, high
bits)
1
Read/Write
Read
2
CPU priority
Priority modes
1
Read/Write
Read
1
Bus error
Application flag
error
0
Read/Clear
Read (0 in HOM)
0
Mode
SAM or HOM
1 (HOM)
Read
Read
-
Mode bit
This bit is a read-only indication of whether the MPUI is in host-only mode
(HOM) or in single-access mode (SAM). HOM and SAM are described in
Section 3.6, MPU Interface.
-
Bus error
This bit is set to 1 if the TIPB bridge generates a bus error (due to a time-out
condition or SAM/HOM change error), indicating that an error signal has
been sent to the DSP CPU, which can read this bit to identify the source of
the error condition. The bit is cleared upon read by the DSP CPU. This bit
cannot be read during HOM (always registers as zero during HOM).
-
CPU priority bit
When CPU_Priority = 1, the DSP subsystem CPU, MPUI, and DMA have
the following priority in arbitration of TIPB bridge accesses:
1) CPU
2) MPUI