Video Port/VCXO Interpolated Control (VIC) Port User's Guide

www.ti.com
5.1.2 Video Port Peripheral Control Register (PCR)
GPIO Registers
The video port peripheral control register (PCR) determines operation during emulation.
Normal operation is to not halt the port during emulation suspend. This allows a displayed image to remain
visible during suspend. However, this will only work if one of the continuous capture/display modes is
selected because non-continuous modes require CPU intervention for EDMAs to continue indefinitely (and
the CPU is halted during emulation suspend).
When FREE = 0, emulation suspend can occur. Clocks and counters continue to run in order to maintain
synchronization with external devices. The video port waits until a field boundary to halt EDMA event
generation, so that upon restart the video port can begin generating events again at the precise point it left
off. After exiting suspend, the video port waits for the correct field boundary to occur and then reenables
EDMA events. The EDMA pointers will be at the correct location for capture/display to resume where it left
off. The emulation suspend operation is similar to the BLKCAP or BLKDISP operation with the difference
being that BLKCAP and BLKDISP operations take effect immediately rather than at field completion and
rely on you to reset the EDMA mechanism before they are cleared.
There is no separate emulation suspend mechanism on the video capture side. The field and frame
operation (see Table 3-6 ) can be used as emulation suspend.
The video port peripheral control register (PCR) is shown in Figure 5-2 and described in Table 5-3 .
Figure 5-2. Video Port Peripheral Control Register (PCR)
31 16
Reserved
R-0
15 3 2 1 0
Reserved PEREN SOFT FREE
R-0 R/W-0 R-0 R/W-1
LEGEND: R/W = Read/Write; R = Read only; - n = value after reset
Table 5-3. Video Port Peripheral Control Register (PCR) Field Descriptions
Bit field
(1)
symval
(1)
Value Description
31-3 Reserved 0 Reserved. The reserved bit location is always read as 0. A value written to this field
has no effect.
2 PEREN OF( value) Peripheral enable bit.
DEFAULT 0 Video port is disabled. Port clock (VCLK1, VCLK2, STCLK) inputs are gated off to
save power. EDMA access to the video port is still acknowledged but indeterminate
DISABLE
read data is returned and write data is discarded.
ENABLE 1 Video port is enabled.
1 SOFT OF( value) Soft bit enable mode bit. This bit is used in conjunction with FREE bit to determine
state of video port clock during emulation suspend. This bit has no effect if FREE = 1.
DEFAULT 0 The current field is completed upon emulation suspend. After completion, no new
EDMA events are generated. The port clocks and counters continue to run in order to
STOP
maintain synchronization. No interrupts are generated. If the port is in display mode,
video control signals continue to be output and the default data value is output during
the active video window.
COMP 1 Is not defined for this peripheral; the bit is hardwired to 0.
0 FREE OF( value) Free-running enable mode bit. This bit is used in conjunction with SOFT bit to
determine state of video port during emulation suspend.
SOFT 0 Free-running mode is disabled. During emulation suspend, SOFT bit determines
operation of video port.
DEFAULT 1 Free-running mode is enabled. Video port ignores the emulation suspend signal and
continues to function as normal.
(1)
For CSL implementation, use the notation VP_PCR_ field_ symval
SPRUEM1 – May 2007 General-Purpose I/O Operation 153
Submit Documentation Feedback