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1125
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Multichannel Audio Serial Port (McASP)
24.0.21.5 Interrupts
24.0.21.5.1 Transmit Data Ready Interrupt
The transmit data ready interrupt (XDATA) is generated if XDATA is 1 in the XSTAT register and XDATA
is also enabled in XINTCTL.
provides details on when XDATA is set in the XSTAT
register.
A transmit start of frame interrupt (XSTAFRM) is triggered by the recognition of transmit frame sync. A
transmit last slot interrupt (XLAST) is a qualified version of the data ready interrupt (XDATA). It has the
same behavior as the data ready interrupt, but is further qualified by having the data requested belonging
to the last slot (the slot that just ended was next-to-last TDM slot, current slot is last slot).
24.0.21.5.2 Receive Data Ready Interrupt
The receive data ready interrupt (RDATA) is generated if RDATA is 1 in the RSTAT register and RDATA
is also enabled in RINTCTL.
provides details on when RDATA is set in the RSTAT
register.
A receiver start of frame interrupt (RSTAFRM) is triggered by the recognition of a receiver frame sync. A
receiver last slot interrupt (RLAST) is a qualified version of the data ready interrupt (RDATA). It has the
same behavior as the data ready interrupt, but is further qualified by having the data in the buffer come
from the last TDM time slot (the slot that just ended was last TDM slot).
24.0.21.5.3 Error Interrupts
Upon detection, the following error conditions generate interrupt flags:
•
In the receive status register (RSTAT):
–
Receiver overrun (ROVRN)
–
Unexpected receive frame sync (RSYNCERR)
–
Receive clock failure (RCKFAIL)
–
Receive DMA error (RDMAERR)
•
In the transmit status register (XSTAT):
–
Transmit underrun (XUNDRN)
–
Unexpected transmit frame sync (XSYNCERR)
–
Transmit clock failure (XCKFAIL)
–
Transmit DMA error (XDMAERR)
Each interrupt source also has a corresponding enable bit in the receive interrupt control register
(RINTCTL) and transmit interrupt control register (XINTCTL). If the enable bit is set in RINTCTL or
XINTCTL, an interrupt is requested when the interrupt flag is set in RSTAT or XSTAT. If the enable bit is
not set, no interrupt request is generated. However, the interrupt flag may be polled.
24.0.21.5.4 Audio Mute (AMUTE) Function
The McASP includes an automatic audio mute function (
) that asserts in hardware the
AMUTE device pin to a preprogrammed output state, as selected by the MUTEN bit in the audio mute
control register (AMUTE). The AMUTE device pin is asserted when one of the interrupt flags is set or an
external device issues an error signal on the AMUTEIN input. Typically, the AMUTEIN input is shared with
a device pin.
The AMUTEIN input allows the on-chip logic to consider a mute input from other devices in the system, so
that all errors may be considered. The AMUTEIN input has a programmable polarity to allow it to adapt to
different devices, as selected by the INPOL bit in AMUTE, and it must be enabled explicitly.
In addition to the external AMUTEIN input, the AMUTE device pin output may be asserted when one of
the error interrupt flags is set and its mute function is enabled in AMUTE.