Setting the Transmit Clock Polarity
8-31
Transmitter Configuration
SPRU592E
8.20 Setting the Transmit Clock Polarity
23) determines the polarity of
the transmit clock.
Figure 8
−
23. Register Bit Used to Set Transmit Clock Polarity
PCR
15
2
1
0
CLKXP
R/W-0
Legend:
R = Read; W = Write; -
n
= Value after reset
Table 8
−
23. Register Bit Used to Set Transmit Clock Polarity
Register
Bit
Name
Function
PCR
1
CLKXP
Transmit Clock Polarity
CLKXP = 0
When the CLKX pin is configured as an input, the signal on
the CLKX pin is not inverted before being used internally.
When CLKX is configured as an output, the internal CLKX
is not inverted before being driven on the CLKX pin.
The transmit data is driven on the rising edge of the external
CLKX signal.
CLKXP = 1
When the CLKX pin is configured as an input, the signal on
the CLKX pin is inverted before being used internally.
When CLKX is configured as an output, the internal CLKX
is not inverted before being driven on the CLKX pin.
The transmit data is driven on the falling edge of the
external CLKX signal.
8.20.1 About Frame Sync Pulses, Clock Signals, and Their Polarities
Transmit frame-sync pulses can be either generated internally by the sample
rate generator or driven by an external source. The source of frame sync is
selected by programming the mode bit, FSXM, in PCR. FSX is also affected
by the FSGM bit in SRGR2. Similarly, transmit clocks can be selected to be
inputs or outputs by programming the mode bit, CLKXM, in the PCR.
When FSR and FSX are inputs (FSXM = FSRM= 0, external frame-sync
pulses), the McBSP detects them on the internal falling edge of clock, internal
CLKR, and internal CLKX, respectively. The receive data arriving at the DR pin
is also sampled on the falling edge of internal CLKR. Note that these internal
clock signals are either derived from external source via CLK(R/X) pins or
driven by the sample rate generator clock (CLKG) internal to the McBSP.
Summary of Contents for TMS320VC5509
Page 5: ...vi This page is intentionally left blank ...
Page 43: ...McBSP Operation 2 20 SPRU592E This page is intentionally left blank ...
Page 105: ...SPI Operation Using the Clock Stop Mode 6 16 SPRU592E This page is intentionally left blank ...
Page 187: ...Transmitter Configuration 8 40 SPRU592E This page is intentionally left blank ...
Page 191: ...General Purpose I O on the McBSP Pins 9 4 SPRU592E This page is intentionally left blank ...
Page 201: ...Emulation Power and Reset Considerations 10 10 SPRU592E ...
Page 207: ...Data Packing Examples 11 6 SPRU592E This page is intentionally left blank ...
Page 273: ...McBSP Register Worksheet 13 14 SPRU592E This page is intentionally left blank ...