Data Transmission and Reception
11-35
Multichannel Buffered Serial Ports
Figure 11–18.
Transmit Operation
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
Write of DXR
(D)
DXR to XSR copy
(C)
Write of DXR
(C)
XRDY
DX
FSX
C5
C6
C7
B0
B2
B3
B4
B5
B6
B7
A0
A1
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ
B1
CLKX
DXR to XSR copy
(B)
11.3.5.3 Maximum Frame Frequency
The frame frequency is determined by the following equation, which calculates
the period between frame synchronization signals:
Ă
Ă
+
Ă
Ą
Ą
Ă
Ă
Ă
Ă
Ă
Ă
Ă
The frame frequency may be increased by decreasing the time between frame
synchronization signals in bit clocks (which is limited only by the number of bits
per frame). As the frame transmit frequency is increased, the inactivity period
between the data frames for adjacent transfers decreases to 0. The minimum
time between frame synchronization pulses is the number of bits transferred per
frame. This time also defines the maximum frame frequency, which is calculated
by the following equation:
Ă
Ă
Ă
+
Ă
Ą
Ą
Ă
Ă
Ă
Ă
Figure 11–19 shows the McBSP operating at maximum frame frequency. The
data bits in consecutive frames are transmitted continuously with no inactivity
between bits. If there is a 1-bit data delay, as shown, the frame synchronization
pulse overlaps the last bit transmitted in the previous frame.