Datasheet

6−3
6.2 C54X HPI Control Register
Bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Name C54X HPI control
Host Type R R R R R/W W R R/W R R R R R/W W R R/W
DSP Type R R R R R/W − R/W − R R R R R/W − R/W −
Default 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Table 6−2. C54X HPI Control Register Description
BIT FIELD NAME HOST TYPE DSP TYPE FUNCTION
15−12
RSVD
R
R
Reserved. These bits return 0s when read.
11 HINT R/W R/W
This bit determines the state of the DSP HINT output which is used to generate an interrupt
to the host. HINT= 0 after reset. The HINT can be set only by the DSP by writing a 1 to
this bit and can be cleared only by the host writing a 1 to this bit.
10 DSPINT W −
Host to DSP interrupt. This bit can only be written by the host and is not readable by the
host or the DSP. When the host writes a 1 to this bit, an interrupt is generated to the DSP.
Writing a 0 has no effect.
9 SMOD R R/W
This bit determines the mode of operation.
0 = HOM is selected (Always during reset)
1 = SAM is selected
8 BOB R/W −
BOB affects both data and address transfers. Only the host can modify this bit and it is
not visible to the DSP. BOB must be initialized before the first data or address register
access.
0 = First byte is the MS
1 = First byte is the LS
7−4 RSVD R R Reserved. These bits return 0s when read.
3 HINT R/W R/W
This bit determines the state of the DSP HINT output which is used to generate an interrupt
to the host. HINT= 0 after reset. The HINT can be set only by the DSP by writing a 1 to
this bit and can be cleared only by the host writing a 1 to this bit.
2 DSPINT W −
Host to DSP interrupt. This bit can only be written by the host and is not readable by the
host or the DSP. When the host writes a 1 to this bit, an interrupt is generated to the DSP.
Writing a 0 has no effect.
1 SMOD R R/W
This bit determines the mode of operation.
0 = HOM is selected (always during reset)
1 = SAM is selected
0 BOB R/W −
BOB affects both data and address transfers. Only the host can modify this bit and it is
not visible to the DSP. BOB must be initialized before the first data or address register
access.
0 = First byte is MS
1 = First byte is the LS
6.2.1 Auto Increment Feature
The HPI data register can be accessed with optional auto-address increment. It provides a convenient way of reading
or writing to subsequent word locations. In the auto-increment mode, the data read causes a postincrement of the
HPI address register and a data write causes a preincrement of the HPI address register. Because the HPI has
2Kx16-bit memory, it uses only the 11 LSBs of the HPI address register but, during the auto-increment operation, all
16 bits will be incremented or decremented.
6.2.2 Interrupts
DSP can interrupt the host by writing to bit 3 (HINT) of the HPI control register. By writing a 1 by the DSP to the HINT
bit of the HPI control register, the HPI can assert its HINT
pin that is connected to the HINT pin of PCI2040. The host
can acknowledge and clear this bit by writing a 1 to this bit. Writing a 0 to the HINT bit has no effect.