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McBSP Basic Programming Model
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21.5.1.5.2.1.3 Enable/Disable the Analog Loopback Mode
The McBSPi.
[15] ALB bit determines whether the analog loopback mode is on or
off.
In the analog loopback mode, the receive signals are connected internally through multiplexers to the
corresponding transmit loop back signals:
•
DR is connected to transmit loop back data on DX input pin
•
FSR is connected to FRX input pin
•
CLKR is connected to the CLKX input pin
This Analog Loopback mode is also done to test the Input/Output buffers, through pads.
21.5.1.5.2.1.4 Enable/disable the synchronous transmit-receive mode (McBSP1 only)
The control registers of the System Control Module is used to configure the synchronous transmit-receive
mode.
The MCBSP1_CLKR bit of the CONTROL_DEVCONF0[3] register is used to select the McBSP1 module
CLKR signal source:
•
When set to ‘0’, the CLKR source is from the CLKR input signal
•
When set to ‘1’, the CLKR source is from the CLKX input signal
The MCBSP1_FSR bit of the CONTROL_DEVCONF0[4] register is used to select the McBSP1 module
FSR signal source:
•
When set to ‘0’, the FSR source is from the FSR input signal
•
When set to ‘1’, the FSR source is from the FSX input signal
21.5.1.5.2.1.5 Enable/Disable the Receive Multichannel Selection Mode
The McBSPi.
[0] RMCM bit determines whether the receive multichannel selection
mode is on or off.
For further details, see
.
21.5.1.5.2.2 Data Behavior
21.5.1.5.2.2.1 Choose 1 or 2 Phases for the Receive Frame
The McBSPi.
[15] RPHASE bit determines whether the receive data frame has one
(Single phase) or two phases (Dual phase). When dual-phase is selected the number of words per phase
must be set to one.
21.5.1.5.2.2.2 Set the Receive Word Length(s)
The McBSPi.
RWDLEN2 bit fields determine how many bits are in each serial word in phase 1 and in phase 2,
respectively, of the receive data frame.
If a single-phase frame is selected, RWDLEN1 selects the length for every serial word received in the
frame.
If a dual–phase frame is selected, RWDLEN1 and RWDLEN2 must be set to select the both length. These
both bits can have values different.
21.5.1.5.2.2.3 Set the Receive Frame Length
The receive frame length is the number of serial words in the receive frame.
The McBSPi.
[14:8]
RFRLEN2 bit fields determine how many serial words are in phase 1 and in phase 2, respectively, of the
receive data frame.
3136
Multi-Channel Buffered Serial Port
SWPU177N – December 2009 – Revised November 2010
Copyright © 2009–2010, Texas Instruments Incorporated
