Mcbsp Exception/Error Conditions - Texas Instruments TMS320VC5501 Reference Manual

McBSP Exception/Error Conditions

4.1 McBSP Exception/Error Conditions
4-2 McBSP Exception/Error Conditions
There are five serial port events that may constitute a system error:
Receiver Overrun (RFULL = 1 in SPCR1). This occurs when DRR1 has
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not been read since the last RBR-to-DRR copy. Consequently, the
receiver does not copy a new word from the RBR(s) to the DRR(s), and
the RSR(s) are now full with another new word shifted in from DR.
Therefore, RFULL = 1 indicates an error condition wherein any new data
that may arrive at this time on DR replaces the contents of the RSR(s), and
as a result, the previous word is lost. The RSR(s) continue to be
overwritten as long as new data arrives on DR and DRR1 is not read.
Unexpected Receive Frame-Sync Pulse (RSYNCERR = 1 in SPCR1).
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This occurs during reception when RFIG = 0 and an unexpected
frame-sync pulse occurs. An unexpected frame-sync pulse is one that
begins the next frame transfer before all the bits of the current frame have
been received. Such a pulse causes data reception to abort and restart.
If new data has been copied into the RBR(s) from the RSR(s) since the last
RBR-to-DRR copy, this new data in the RBR(s) is lost. This is because no
RBR-to-DRR copy occurs; the reception has been restarted.
Transmitter Data Overwrite. This occurs when the CPU or the DMA
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controller overwrites data in the DXR(s) before the data is copied to the
XSR(s). The overwritten data never reaches the DX pin.
Transmitter Underflow (XEMPTY = 0 in SPCR2). If a new frame-sync
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signal arrives before new data is loaded into DXR1, the previous data in
the DXR(s) is sent again. This will continue for every new frame-sync
pulse that arrives until DXR1 is loaded with new data.
Unexpected Transmit Frame-Synch Pulse (XSYNCERR = 1 in
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SPCR2). This occurs during transmission when XFIG = 0 and an
unexpected frame-sync pulse occurs. An unexpected frame-sync pulse is
one that begins the next frame transfer before all the bits of the current
frame have been transferred. Such a pulse causes the current data
transmission to abort and restart. If new data has been written to the
DXR(s) since the last DXR-to-XSR copy, the current value in the XSR(s)
is lost.
SPRU592E