Motorola DSP56301 Host Interface Control Register Hctr Bit Definitions, Twsd PCI, Host Semaphores

Models: DSP56301

1 372
Download 372 pages 304 b
Page 167
Image 167

 

 

 

 

 

Host-Side Programming Model

 

 

 

 

 

 

 

 

 

 

 

Table 6-22.Host Interface Control Register (HCTR) Bit Definitions

 

 

 

 

 

 

 

 

 

 

Bit

Bit Name

Reset

Mode

Description

 

 

Number

Value

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

31–20

 

0

 

Reserved. Write to zero for future compatibility.

 

 

 

 

 

 

 

 

 

 

 

19

TWSD

0

PCI

Target Wait State Disable

 

 

 

 

 

 

Note: Do not set the TWSD bit. This bit is reserved. The HI32 may

 

 

 

 

 

 

operate improperly in PCI mode when the Target Wait State

 

 

 

 

 

 

Disable (TWSD) bit is set.

 

 

 

 

 

 

 

 

 

 

 

 

 

Disables PCI wait states (which are inserted by deasserting

HTRDY)

 

 

 

 

 

 

 

during a data phase. If TWSD is cleared and the HI32 is in PCI mode

 

 

 

 

 

 

(DCTR[HM] = $1):

 

 

 

 

 

 

ν as the selected target in a read data phase from the HRXS, the

 

 

 

 

 

 

HI32 inserts PCI wait states if the HRXS is empty (HRRQ = 0).

 

 

 

 

 

 

Wait states are inserted until the data is transferred from the DSP

 

 

 

 

 

 

side to the HRXS. Up to eight wait states can be inserted before a

 

 

 

 

 

 

target initiated transaction termination (disconnect-C/Retry) is

 

 

 

 

 

 

generated.

 

 

 

 

 

 

ν as the selected target in a write data phase to the HTXR, the HI32

 

 

 

 

 

 

inserts PCI wait states if the HTXR is full (HTRQ = 0). Wait states

 

 

 

 

 

 

are inserted until the data is transferred from the HTXR to the DSP

 

 

 

 

 

 

side. Up to eight wait states can be inserted before a target

 

 

 

 

 

 

initiated transaction termination (disconnect-C/Retry) is generated.

 

 

 

 

 

 

ν as the selected target in a write data phase to the HCVR, the HI32

 

 

 

 

 

 

inserts PCI wait states if a host command is pending (HC = 1).

 

 

 

 

 

 

Wait states are inserted until the pending host command is

 

 

 

 

 

 

serviced. Up to eight wait states can be inserted before a target

 

 

 

 

 

 

initiated transaction termination (disconnect-C/Retry) is generated.

 

 

 

 

 

 

If TWSD is set and the HI32 is in the PCI mode (DCTR[HM] = $1):

 

 

 

 

 

 

ν as the selected target in a read transaction from the HRXS, the

 

 

 

 

 

 

HI32 generates a target initiated transaction termination

 

 

 

 

 

 

(disconnect-C) if the HRXS is empty (HRRQ = 0).

 

 

 

 

 

 

ν as the selected target in a write transaction to the HTXR, the HI32

 

 

 

 

 

 

generates a target initiated transaction termination (disconnect-C)

 

 

 

 

 

 

if the HTXR is full (HTXR = 0).

 

 

 

 

 

 

ν as the selected target in a write transaction to the HCVR, the HI32

 

 

 

 

 

 

generates a target initiated transaction termination (disconnect-C)

 

 

 

 

 

 

if a host command is pending (HC = 1).

 

 

 

 

 

 

TWSD is ignored when the HI32 is not in PCI mode (DCTR[HM]$1).

 

 

 

 

 

 

The personal hardware reset clears TWSD.

 

 

 

 

 

 

 

 

 

18–17

 

0

 

Reserved. Write to zero for future compatibility.

 

 

 

 

 

 

 

 

 

16–14

HS[2–0]

0

UBM

Host Semaphores

 

 

 

 

 

PCI

Used by the host processors for software arbitration of mastership over

 

 

 

 

 

 

the HI32. These bits do not affect the HI32 operation and serve only as a

 

 

 

 

 

 

read/write semaphore repository. These bits can be used as a mailbox

 

 

 

 

 

 

between the external hosts. For example, the semaphores can assist

 

 

 

 

 

 

HI32 bus arbitration among several external hosts. All external host

 

 

 

 

 

 

processors that compete for mastership over the HI32 should work

 

 

 

 

 

 

according to the same software protocol for handling over the HI32 from

 

 

 

 

 

 

one host processor to another.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Host Interface (HI32)

6-49

Page 167
Image 167
Motorola DSP56301 Host Interface Control Register Hctr Bit Definitions, Bit Bit Name Reset Mode Description Number