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Architecture
11.2.8.5 Receiver Configuration
To configure the McBSP receiver, perform the following procedure:
1. Place the McBSP/receiver in reset.
2. Program the McBSP registers for the desired receiver operation.
3. Take the receiver out of reset.
11.2.8.5.1 Programming the McBSP Registers for the Desired Receiver Configuration
The following is a list of important tasks to be performed when you are configuring the McBSP receiver.
Each task corresponds to one or more McBSP register bit fields. Note that SRG is Sample Rate
Generator.
Global Behavior
1. Set the receiver pins to operate as McBSP pins.
2. Enable/disable the digital loop back mode.
3. Enable/disable the analog loop back mode.
4. Enable/disable the synchronous transmit-receive mode.
5. Enable/disable the receive multichannel selection mode.
Data behavior:
1. Choose 1 or 2 phases for the receive frame.
2. Set the receive word length(s).
3. Set the receive frame length (one word per phase if dual-phase selected).
4. Enable/disable the receive frame–synchronization ignore function.
5. Set the receive data delay.
6. Set the receive sign–extension and justification mode.
7. Set the receive interrupt mode.
Frame–synchronization behavior:
1. Set the receive frame–synchronization mode.
2. Set the receive frame–synchronization polarity.
3. Set the sample rate generator (SRG) frame–synchronization period and pulse width.
Clock behavior:
1. Set the receive clock mode.
2. Set the receive clock polarity.
3. Set the SRG clock divide–down value.
4. Set the SRG clock synchronization mode.
5. Set the SRG clock mode (choose an input clock).
6. Set the SRG input clock polarity.
11.2.8.5.2 Resetting and Enabling the Receiver
The first step of the receiver configuration procedure is to reset the receiver, and the last step is to
enable the receiver (to take it out of reset).
The serial port can be reset in the following two ways:
•
A global reset places the receiver, transmitter, and sample rate generator in reset. When the device
reset is removed, GRST, FRST, RRST and XRST bits = 0, keeping the entire serial port in the reset
state.
•
The serial port transmitter and receiver can be reset directly using the RRST and XRST bits in the
SPCR1_REG register. The sample rate generator can be reset directly using the GRST bit in
SPCR2_REG[6] register.
1158
Multichannel Buffered Serial Port (McBSP)
Preliminary
© 2011, Texas Instruments Incorporated
www.ti.com
SPRUGX9 – 15 April 2011
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