Texas Instruments OMAP5912 Reference Manual page 1640

2.3.6 Frame Frequency
Equation 1. McBSP Frame Frequency
2.3.7 Maximum Frame Frequency
Equation 2. McBSP Maximum Frame Frequency
Figure 9. McBSP Operating at Maximum Packet Frequency
CLK(R/X)
FS(R/X)
A2
D(R/X)
SPRU762B
You can also use the frame-synchronization ignore function for data packing
(for more details, see section 11.2).
The frame frequency is determined by the period between frame-synchronization
pulses and is defined as shown by Equation 1.
Frame Frequency +
The frame frequency can be increased by decreasing the time between
frame-synchronization pulses (limited only by the number of bits per frame).
As the frame transmit frequency increases, the inactivity period between the
data packets for adjacent transfers decreases to zero.
The minimum number of clock cycles between frame synchronization pulses
is equal to the number of bits transferred per frame. The maximum frame
frequency is defined as shown by Equation 2.
Maximum Frame Frequency +
Figure 9 shows the McBSP operating at maximum packet frequency. At
maximum packet frequency, the data bits in consecutive packets are
transmitted contiguously with no inactivity between bits.
A1 A0 B7 B6
If there is a 1-bit data delay as shown in this figure, the frame-synchronization
pulse overlaps the last bit transmitted in the previous frame. Effectively, this
permits a continuous stream of data, making frame-synchronization pulses
redundant. Theoretically, only an initial frame-synchronization pulse is
required to initiate a multipacket transfer.
Clock Frequency
Number of Clock Cycles Between Frame−Sync Pulses
Number of Bits Per Frame
B5 B4 B3
Multichannel Buffered Serial Ports (McBSPs)
McBSP Operation
Clock Frequency
B2 B1 B0 C7 C6
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