
Public Version
McBSP Integration
www.ti.com
Table 21-6. McBSP Smart Idle Mode Configuration Behavior
CLKRM Bit
CLKXM Bit
McBSP Mode
Source of
CLOCKACTIVITY
Behavior
Functional
Bit
Clock
0
0
Slave
outside
0bXX
The module acknowledges the idle request as
soon as there is no pending DMA, interrupt
request or transmit buffer threshold
synchronization (only when wake-up event is set
on transmit threshold reached), regardless of the
CLOCKACTIVITY settings or receive and transmit
activity.
0
1
Transmit
McBSPi_ICLK
0b0X
The McBSP will not acknowledge the idle request
Master
unless:
CLKS
0bX0
• The transmit part is disabled (XDISABLE) or
under software reset (XRST) and the receive
part is not using the transmit loop-back clock
(CLKR is not connected to the CLKX input
pin).
• Both transmit and receive parts are disabled
(XDISABLE/RDISABLE) or under software
reset (XRST/RRST)
The idle acknowledge is asserted as soon as
there is no pending DMA, interrupt request or
transmit/receive buffer threshold synchronization
(only when wake-up event is set on
transmit/receive threshold reached) and the
pending transmit and/or receive frames were
completed in case of transmit and/or receive
disable.
McBSPi_ICLK
0b1X
The module acknowledges the idle request as
soon as there is no pending DMA, interrupt
CLKS
0bX1
request or transmit/receive buffer threshold
synchronization (only when wake-up event is set
on transmit/receive threshold reached).
CLKR (outside)
0bXX
The module acknowledges the idle request as
soon as there is no pending DMA, interrupt
request or transmit/receive buffer threshold
synchronization (only when wake-up event is set
on transmit/receive threshold reached), regardless
of the CLOCKACTIVITY settings.
1
0
Receive
McBSPi_ICLK
0b0X
The McBSP will not acknowledge the idle request
master
unless: The receive part is disabled (RDISABLE)
CLKS
0bX0
or under software reset (RRST)
The Idle acknowledge is asserted as soon as
there is no pending DMA, interrupt request or
transmit/receive buffer threshold synchronization
(only when wake-up event is set on
transmit/receive threshold reached) and the
pending transmit and/or receive frames where
completed in case of transmit and/or receive
disable.
McBSPi_ICLK
0b1X
The module acknowledges the idle request as
soon as there is no pending DMA, interrupt
CLKS
0bX1
request or transmit/receive buffer threshold
synchronization (only when wake-up event is set
on transmit/receive threshold reached).
CLKX
0bXX
When CLKX is used as source (functional clock is
provided from outside) then the module
acknowledges the idle request as soon as there is
no pending DMA, interrupt request or
transmit/receive buffer threshold synchronization
(only when wake-up event is set on
transmit/receive threshold reached), regardless of
the CLOCKACTIVITY settings.
3084
Multi-Channel Buffered Serial Port
SWPU177N – December 2009 – Revised November 2010
Copyright © 2009–2010, Texas Instruments Incorporated