every CLKG cycle until it reaches 0, at which time FSG goes low. At the same time, the frame period value
(FPER + 1) is also counting down. When this value reaches 0, FSG goes high, indicating a new frame.
15.7.17 Set the Receive Clock Mode
shows the settings for bits used to set receive clock mode.
Table 15-40. Register Bits Used to Set the Receive Clock Mode
Register
Bit
Name
Function
Type
Reset
Value
PCR
8
CLKRM
Receive clock mode
R/W
0
Case 1: Digital loopback mode not set (DLB = 0) in SPCR1.
CLKRM = 0
The MCLKR pin is an input pin that supplies the
internal receive clock (MCLKR).
CLKRM = 1
Internal MCLKR is driven by the sample rate
generator of the McBSP. The MCLKR pin is an
output pin that reflects internal MCLKR.
Case 2: Digital loopback mode set (DLB = 1) in SPCR1.
CLKRM = 0
The MCLKR pin is in the high impedance state.
The internal receive clock (MCLKR) is driven by
the internal transmit clock (CLKX). Internal CLKX is
derived according to the CLKXM bit of PCR.
CLKRM = 1
Internal MCLKR is driven by internal CLKX. The
MCLKR pin is an output pin that reflects internal
MCLKR. Internal CLKX is derived according to the
CLKXM bit of PCR.
SPCR1
15
DLB
Digital loopback mode
R/W
00
DLB = 0
Digital loopback mode is disabled.
DLB = 1
Digital loopback mode is enabled. The receive
signals, including the receive frame-synchronization
signal, are connected internally through multiplexers
to the corresponding transmit signals.
SPCR1
12-11
CLKSTP
Clock stop mode
R/W
00
CLKSTP = 0Xb
Clock stop mode disabled; normal clocking for non-
SPI mode.
CLKSTP = 10b
Clock stop mode enabled without clock delay.
The internal receive clock signal (MCLKR) and
the internal receive frame-synchronization signal
(FSR) are internally connected to their transmit
counterparts, CLKX and FSX.
CLKSTP = 11b
Clock stop mode enabled with clock delay.
The internal receive clock signal (MCLKR) and
the internal receive frame-synchronization signal
(FSR) are internally connected to their transmit
counterparts, CLKX and FSX.
15.7.17.1 Selecting a Source for the Receive Clock and a Data Direction for the MCLKR Pin
shows how you can select various sources to provide the receive clock signal and affect the MCLKR
pin. The polarity of the signal on the MCLKR pin is determined by the CLKRP bit.
In the digital loopback mode (DLB = 1), the transmit clock signal is used as the receive clock signal.
Also, in the clock stop mode, the internal receive clock signal (MCLKR) and the internal receive frame-
synchronization signal (FSR) are internally connected to their transmit counterparts, CLKX and FSX.
Multichannel Buffered Serial Port (McBSP)
934
TMS320x2806x Microcontrollers
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
Copyright © 2022 Texas Instruments Incorporated
Summary of Contents for TMS320 2806 Series
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