Table 15-91. PCR Register Field Descriptions (continued)
Bit
Field
Type
Reset
Description
9
CLKXM
R/W
0h
Transmit clock mode bit.
CLKXM determines whether the source for the transmit clock is
external or internal, and whether the MCLKX pin is an input or an
output. The polarity of the signal on the MCLKX pin is determined by
the CLKXP bit.
In the clock stop mode (CLKSTP = 10b or 11b), the McBSP can act
as a master or as a slave in the SPI protocol. If the McBSP is a
master, make sure that CLKX is an output. If the McBSP is a slave,
make sure that CLKX is an input.
Reset type: SYSRSn
0h (R/W) = Not in clock stop mode (CLKSTP = 00b or 01b):
The transmitter gets its clock signal from an external source via the
MCLKX pin.
In clock stop mode (CLKSTP = 10b or 11b):
The McBSP is a slave in the SPI protocol. The internal transmit clock
(CLKX) is driven by the SPI master via the MCLKX pin. The internal
receive clock (MCLKR) is driven internally by CLKX, so that both
the transmitter and the receiver are controlled by the external master
clock.
1h (R/W) = Not in clock stop mode (CLKSTP = 00b or 01b):
Internal CLKX is driven by the sample rate generator of the McBSP.
The MCLKX pin is an output pin that reflects internal CLKX.
In clock stop mode (CLKSTP = 10b or 11b):
The McBSP is a master in the SPI protocol. The sample rate
generator drives the internal transmit clock (CLKX). Internal CLKX
is reflected on the MCLKX pin to drive the shift clock of the
SPI-compliant slaves in the system. Internal CLKX also drives the
internal receive clock (MCLKR), so that both the transmitter and the
receiver are controlled by the internal master clock
8
CLKRM
R/W
0h
Receive clock mode bit.
The role of CLKRM and the resulting effect on the MCLKR pin
depend on whether the McBSP is in the digital loopback mode (DLB
= 1).
The polarity of the signal on the MCLKR pin is determined by the
CLKRP bit.
Reset type: SYSRSn
0h (R/W) = Not in digital loopback mode (DLB = 0):
The MCLKR pin is an input pin that supplies the internal receive
clock (MCLKR).
In digital loopback mode (DLB = 1):
The MCLKR pin is in the high impedance state. The internal receive
clock (MCLKR) is driven by the internal transmit clock (CLKX). CLKX
is derived according to the CLKXM bit.
1h (R/W) = Not in digital loopback mode (DLB = 0):
Internal MCLKR is driven by the sample rate generator of the
McBSP. The MCLKR pin is an output pin that reflects internal
MCLKR.
In digital loopback mode (DLB = 1):
Internal MCLKR is driven by internal CLKX. The MCLKR pin is an
output pin that reflects internal MCLKR. CLKX is derived according
to the CLKXM bit.
Multichannel Buffered Serial Port (McBSP)
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
TMS320x2806x Microcontrollers
987
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Содержание TMS320 2806 Series
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