Frame Sync Generation In The Sample Rate Generator - Texas Instruments TMS320VC5501 Reference Manual

3.3 Frame Sync Generation in the Sample Rate Generator

3.3.1 Choosing the Width of the Frame-Sync Pulse on FSG
3.3.2 Controlling the Period Between the Starting Edges of Frame-Sync Pulses on
FSG
SPRU592E
The sample rate generator can produce a frame-sync signal (FSG) for use by
the receiver, the transmitter, or both.
If you want the receiver to use FSG for frame synchronization, set FSRM = 1.
(When FSRM = 0, receive frame synchronization is supplied via the FSR pin.)
If you want the transmitter to use FSG for frame synchronization, you must
set:
FSXM = 1 in PCR: This indicates that transmit frame synchronization is
-
supplied by the McBSP itself rather than from the FSX pin.
FSGM = 1 in SRGR2: This indicates that when FSXM = 1, transmit frame
-
synchronization is supplied by the sample rate generator. (When
FSGM = 0 and FSXM = 1, the transmitter uses frame-sync pulses
generated every time data is transferred from DXR[1,2] to XSR[1,2].)
In either case, the sample rate generator must be enabled (GRST = 1) and the
frame-sync logic in the sample rate generator must be enabled (FRST = 1).
Each pulse on FSG has a programmable width. You program the FWID bits
of SRGR1, and the resulting pulse width is (FWID + 1) CLKG cycles, where
CLKG is the output clock of the sample rate generator.
You can control the amount of time from the starting edge of one FSG pulse
to the starting edge of the next FSG pulse. This period is controlled in one of
two ways, depending on the configuration of the sample rate generator:
If the sample rate generator is using an external input clock and
-
GSYNC = 1 in SRGR2, FSG pulses in response to an inactive-to-active
transition on the FSR pin. Thus, the frame-sync period is controlled by an
external device.
Otherwise, you program the FPER bits of SRGR2, and the resulting
-
frame-sync period is (FPER + 1) CLKG cycles, where CLKG is the output
clock of the sample rate generator.
Frame Sync Generation in the Sample Rate Generator
Sample Rate Generator of the McBSP 3-9