Registers
1260
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Multichannel Buffered Serial Port (McBSP)
Table 25-34. Pin Control Register (PCR) Field Descriptions (continued)
Bit
Field
Value
Description
8
CLKRM
Receive clock mode bit.
Digital loop back mode is disabled (DLB = 0 in SPCR):
0
CLKR is an input pin and is driven by an external clock.
1
CLKR is an output pin and is driven by the internal sample-rate generator.
Digital loop back mode is enabled (DLB = 1 in SPCR):
0
Receive clock (not the CLKR pin) is driven by transmit clock (CLKX) that is based on CLKXM bit.
CLKR pin is in high-impedance state.
1
CLKR is an output pin and is driven by the transmit clock. The transmit clock is based on CLKXM
bit.
7
SCLKME
Sample rate generator input clock mode bit. The sample rate generator can produce a clock signal,
CLKG. The frequency of CLKG is:
CLKG frequency = Input clock frequency/( 1)
SCLKME is used in conjunction with the CLKSM bit in the sample rate generator register (SRGR) to
select the input clock.
A CPU reset selects the McBSP internal input clock as the input clock and forces the CLKG
frequency to 1/2 the McBSP internal input clock frequency.
0
The input clock for the sample rate generator is taken from the CLKS pin or from the McBSP
internal input clock, depending on the value of the CLKSM bit in SRGR:
SCLKME
CLKSM
Input Clock for Sample Rate Generator
0
0
Signal on CLKS pin
0
1
McBSP internal input clock
1
The input clock for the sample rate generator is taken from the CLKR pin or from the CLKX pin,
depending on the value of the CLKSM bit in SRGR:
SCLKME
CLKSM
Input Clock for Sample Rate Generator
1
0
Signal on CLKR pin
1
1
Signal on CLKX pin
6
Reserved
0
Reserved. The reserved bit location is always read as 0. A value written to this field has no effect. If
writing to this field, always write the default value of 0 to ensure proper McBSP operation.
5-4
Reserved
0
Reserved. The reserved bit location is always read as 0. A value written to this field has no effect.
3
FSXP
Transmit frame-synchronization polarity bit.
0
Transmit frame-synchronization pulse is active high.
1
Transmit frame-synchronization pulse is active low.
2
FSRP
Receive frame-synchronization polarity bit.
0
Receive frame-synchronization pulse is active high.
1
Receive frame-synchronization pulse is active low.
1
CLKXP
Transmit clock polarity bit.
0
Transmit data driven on rising edge of CLKX.
1
Transmit data driven on falling edge of CLKX.
0
CLKRP
Receive clock polarity bit.
0
Receive data sampled on falling edge of CLKR.
1
Receive data sampled on rising edge of CLKR.