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McBSP Functional Description
•
Unexpected receive frame-synchronization pulse (McBSPi.
[0]
RSYNCERR bit is set to 1, and legacy mode McBSPi.
[3] RSYNCERR bit is
set to 1).
This occurs during reception when an unexpected frame-synchronization pulse arrives. An unexpected
frame-synchronization pulse is one that is supposed to begin the next frame transfer before all the bits
of the current frame have been received. Such a pulse is ignored by the receiver, but sets the
McBSPi.
[3] RSYNCERR bit. For more details about receive
frame-synchronization errors, see
, Unexpected Receive Frame-Sync Pulse.
•
Receiver underflow (McBSPi.
[4] RUNDFLSTAT bit is set to ‘1’)
This occurs when sDMA controller or MPU/IVA2.2 subsystem reads data from an empty receive buffer.
For more details about underflow in the receiver, see
•
Transmitter underflow (McBSPi.
[11] XUNDFLSTAT bit is set to ‘1’, and
legacy mode McBSPi.
[2] XEMPTY bit is set to ‘0’)
If a new frame-synchronization signal arrives when XB is empty, the previous data in the XSR is sent
again. This procedure continues for every new frame-synchronization pulse that arrives until
McBSPi.
register is loaded with new data (and the XB is no longer empty). For
more details about underflow in the transmitter, see
•
Unexpected transmit frame-synchronization pulse (McBSPi.
[7]
XSYNCERR bit is set to ‘1’, and legacy mode McBSPi.
[3] XSYNCERR bit is
set to ‘1’)
This occurs during transmission when an unexpected frame-synchronization pulse arrives. An
unexpected pulse is one that is supposed to begin the next frame transfer before all the bits of the
current frame have been transferred. Such a pulse is ignored by the transmitter, but sets the
McBSPi.
[3] XSYNCERR bit. For more details see
.
•
Transmitter overflow (McBSPi.
[12] XOVFLSTAT bit is set to ‘1’)
This occurs when sDMA controller or MPU/IVA2.2 subsystem writes data to a full XB. For more details
about underflow in the receiver, see
21.4.4.2 Overrun in the Receiver
When McBSPi.
[5] ROVFLSTAT bit set to ‘1’, and
McBSPi.
[2] RFULL bit set to ‘1’ (legacy mode) indicates that the receiver has
experienced overrun and is in an error condition. Receive overrun is set when all of the following
conditions are met:
1. McBSPi.
is not read even if the McBSPi.
[3]
RRDY bit is set (legacy mode) and DMA or interrupt request has been asserted.
2. RB is full
3. RSR is full
As previously described, data arriving on mcbspi_dr is continuously shifted into the Receive Shift Register
(RSR). Once a complete word is shifted into the RSR, an RSR-to-RB copy can occur only if the RB is not
full.
Either of the following events clears the legacy mode McBSPi.
[2] RFULL bit and
allows subsequent transfers to be read properly:
•
The MPU/IVA2.2 subsystems or sDMA controller reads McBSPi.
•
The receiver is reset individually (McBSPi.
[0] RRST bit =0) or as part of a
global reset.
Another frame-synchronization pulse is required to restart the receiver.
According to the McBSPi.
register setting, this condition can generate the
McBSPi_IRQ line to be asserted low. Writing 1 to the corresponding bit in
McBSPi.
register clears the interrupt.
shows the receive overrun condition.
3109
SWPU177N – December 2009 – Revised November 2010
Multi-Channel Buffered Serial Port
Copyright © 2009–2010, Texas Instruments Incorporated
Содержание OMAP36 Series
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Страница 3054: ...3054 Multichannel SPI SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
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