Programmable Clock and Framing
11-54
11.5.1 Sample Rate Generator Clocking and Framing
The sample rate generator is composed of a 3-stage clock divider that provides
a programmable data clock (CLKG) and framing signal (FSG), as shown in
Figure 11–38. CLKG and FSG are McBSP internal signals that can be pro-
grammed to drive receive and/or transmit clocking, CLK(R/X), and framing,
FS(R/X). The sample rate generator can be programmed to be driven by an inter-
nal clock source or an internal clock derived from an external clock source. The
three stages of the sample rate generator circuit compute:
-
Clock divide-down (CLKGDV): The number of input clocks per data bit
clock
-
Frame period (FPER): The frame period in data bit clocks
-
Frame width (FWID): The width of an active frame pulse in data bit clocks
In addition, a frame pulse detection and clock synchronization module allows
synchronization of the clock divide-down with an incoming frame pulse. The
operation of the sample rate generator during device reset is described in
section 11.3.1.
Figure 11–38.
Sample Rate Generator
CLKS
CLKSP
FSR
GSYNC
FSG
CLKG
CLKSM
CLKGDV
FPER
FWID
pulse
Frame
synchronization
and clock
detection
Frame pulse
internal clock source†
1
0
CLKSRG
† ’C6201/C6202/C6701 uses CPU clock as the internal clock source to the sample rate generator.
’C6211/C6711 uses CPU/2 clock as the internal clock source to the sample rate generator.