Preliminary
Architecture
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6.2.9.2.2.2 Audio FIFO Error (Underflow and Overflow)
The underflow and overflow status are required and highlighted by sending interrupt requests IRQs).
The FIFO underflow condition occurs when the HDMI core is requesting data from the FIFO when the
FIFO is empty. The status can be read through the HDMI_WP_IRQSTATUS[8]
AUDIO_FIFO_UNDERFLOW_INTR bit.
The underflow IRQ may happen during a sequence only if one of the following occurs:
•
The audio data path is not set correctly. In this case, the device EDMA cannot fill the FIFO fast
enough.
•
It is the end of the sequence and the number of samples is not a multiple of two times the value in
the HDMI_WP_AUDIO_CFG2[7:0] BLOCK_SIZE bit field (384 samples by default).
The FIFO filling must be ensured by the system before the HDMI core is enabled; this means that in
steady state the filling of the FIFO is always four words of 32 bits (except at the end).
The FIFO overflow condition occurs when an audio data is written (by the device EDMA or MPU
modules) while the FIFO is full. The status can be read through the HDMI_WP_IRQSTATUS[9]
AUDIO_FIFO_OVERFLOW_INTR bit.
The overflow IRQ may happen only if:
•
The device EDMA module does not respect the DMA transfer length.
•
The threshold is not set to the correct value in the HDMI_WP_AUDIO_CTRL[8:0]
TRESHOLD_VALUE bit field.
•
The device MPU module does not check the filling of the FIFO when the audio data is requested
through an IRQ.
6.2.9.2.2.3 Audio FIFO Reset
The audio sample in the FIFO can be flushed by writing 0 in the HDMI_WP_AUDIO_CTRL[31]
WRAPPER_ENABLE bit. As soon as the enable signal is deactivated (set to 0),the following occur: 1.
The audio FIFO is reset. 2. The read and write pointers are reset. 3. The DSS_HDMI_DMA signal is
deasserted. 4. Only the threshold value in the HDMI_WP_AUDIO_CTRL[8:0] TRESHOLD_VALUE bit
field is kept.
6.2.9.2.3 Audio FIFO Data Formats
The format of the audio data in the audio FIFO can be configured through the
HDMI_WP_AUDIO_CFG[4] IEC bit field.
•
IEC = 0: The audio format is L-PCM.
•
IEC = 1: The audio format is IEC 60958/IEC 61937.
6.2.9.2.3.1 L-PCM Format in Audio FIFO
describes the 16-bit data format in the audio FIFO.
Table 6-12. PCM, 16-Bit Format
Order
Bits [31:16]
Bits [15:0]
---
16 bits, 2 channels (stereo)
---
1
Right - Channel 2
Left - Channel 1
---
16 bits, 4 channels
---
1
Right - Channel 2
Left - Channel 1
2
Right - Channel 4
Left - Channel 3
3
Right - Channel 2
Left - Channel 1
4
Right - Channel 4
Left - Channel 3
---
16 bits, 8 channels
---
1
Right - Channel 2
Left - Channel 1
710 High-Definition Multimedia Interface (HDMI)
SPRUGX9 – 15 April 2011
© 2011, Texas Instruments Incorporated
Содержание TMS320C6A816 Series
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