
Philips Semiconductors
Audio In
PRODUCT SPECIFICATION
8-7
8.10
ERROR BEHAVIOR
If either an OVERRUN or HBE error occurs, input sam-
pling is temporarily halted, and samples will be lost. In
case of OVERRUN, sampling resumes as soon as the
DSPCPU makes one or more new buffers available
through an ACK1 or ACK2 operation. In the case of HBE,
sampling will resume as soon as the internal buffer is
written to SDRAM.
HBE and OVERRUN are ‘sticky’ error flags. They will re-
main set until an explicit ACK_HBE or ACK_OVR.
8.11
DIAGNOSTIC MODE
Diagnostic mode is entered by setting the DIAGMODE
bit in the AI_CTL register. In diagnostic mode, the
AI_SCK, AI_WS and AI_SD inputs of the serial-parallel
converter are taken from the output pins of the TM1300
AO unit. This mode can be used during the diagnostic
phase of system boot to verify correct operation of most
of the AI unit and AO unit logic circuitry.
Note that the inputs are truly taken from the TM1300 AO
external pins, i.e. if an external (board level) source is
driving AO_SCK or AO_WS, diagnostic mode is not ca-
pable of testing Audio Out.
Special care must be taken to enable diagnostic mode.
The recommended way of entering diagnostic mode is:
setup the AO unit such that an AO_SCK is generated
set DIAGMODE bit followed by a 5 (AI_SCK) cycle
delay
perform a software reset of the AI unit and immedi-
ately set the DIAGMODE bit back to ‘1’.
BUF2_FULL
If ‘1’, buffer 2 is full. If BUF2_INTEN is also
‘1’, an interrupt request (source 11) is
pending. BUF2_FULL is cleared by writing
a ‘1’ to ACK2, at which point the AI hard-
ware will assume that BASE2 and SIZE
describe a new empty buffer.
0 after RESET.
HBE
Highway Bandwidth Error. Condition raised
when the 64-byte internal AI buffer is not
yet written to SDRAM when a new input
sample arrives. Indicates insufcient allo-
cation of TM1300 highway bandwidth for
the audio sampling rate/mode. Refer to
Chapter 20, “Arbiter.”
0 after RESET.
OVERRUN
OVERRUN error occurred, i.e. the CPU did
not provide an empty buffer in time, and 1
or more samples were lost. If OVR_INTEN
is also 1, an interrupt request (source 11)
is pending. The OVERRUN ag can ONLY
be cleared by writing a ‘1’ to ACK_OVR.
0 after RESET.
Table 8-9. AI MMIO control elds
Field Name
Description
RESET
The AI logic is reset by writing a 0x80000000
to AI_CTL. This bit always reads as a ‘0’.
See Section 8.7, “Audio In Operation” for
details on software reset.
DIAGMODE
0
normal operation (RESET default)
1
diagnostic mode (see Section 8.11,
“Diagnostic Mode”)
SLEEPLESS
0
participate in global power down
(RESET default)
1
refrain from participating in power down
CAP_ENABLE
Capture Enable ag. If 1, AI unit captures
samples and acts as DMA master to write
samples to local SDRAM. If ’0’ (RESET
default), AI unit is inactive.
BUF1_INTEN
Buffer 1 full Interrupt Enable. Default 0.
0
no interrupt
1
interrupt (SOURCE 11) if buffer 1 full
BUF2_INTEN
Buffer 2 full interrupt enable. Default 0
0
no interrupt
1
interrupt (SOURCE 11) if buffer 2 full
HBE_INTEN
HBE Interrupt Enable. Default 0.
0
no interrupt
1
interrupt (SOURCE 11) if a highway
bandwidth error occurs.
Table 8-8. AI MMIO status elds (read only)
Field Name
Description
OVR_INTEN
Overrun Interrupt Enable. Default 0
0
no interrupt
1
interrupt (SOURCE 11) if an overrun
error occurs
ACK1
Write a ’1’ to clear the BUF1_FULL ag and
remove any pending BUF1_FULL interrupt
request. This bit always reads as 0.
ACK2
Write a ’1’ to clear the BUF2_FULL ag and
remove any pending BUF2_FULL interrupt
request. This bit always reads as 0.
ACK_HBE
Write a ’1’ to clear the HBE ag and
remove any pending HBE interrupt request.
This bit always reads as 0.
ACK_OVR
Write a ’1’ to clear the OVERRUN ag and
remove any pending OVERRUN interrupt
request. This bit always reads as 0.
Table 8-9. AI MMIO control elds
Field Name
Description