MT92220BG Zarlink Semiconductor, MT92220BG Datasheet - Page 82

• Manufacturer Part Number: MT92220BG
• Description: Description = 1023 Channel Voice Over IP/AAL2 Processor ;; Package Type = Epbga ;; No. Of Pins = 608
• Manufacturer: Zarlink Semiconductor

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I
Next Packet
Assembled Starting
With This Byte
Buf Size
V
Extra Delay Frames
TX Silence
Suppression
Structure Base
Number of Bearers
Samples per packet
at x Kbps
Bearer X - Circular
Buffer Base Address
Bearers
Field
Init bit. This field is cleared by software upon initialization of an xxPCM channel
addition to a TX RTP connection. It is then set by hardware when an “Assembly Event
- Service xxPCM RTP Channel” is received having the ST bit set. Packets are only
sent when this bit is read at ‘1’ from the xxPCM Channel addition to TX RTP
Connection Structure.
When the I bit is cleared, this field contains the number of frames in the first virtual
xxPCM that will be sent when the I bit is first set by hardware. When the first
“Assembly Event - Service xxPCM RTP Channel” with ST bit set is received, no
packet is sent out, but this field is initialized to its value plus the current TX TDM
Circular Buffer Write pointer. In this way, the first packet to be sent out can be timed to
only contain valid voice samples, since this feature enables the software to “drop” the
N first packets. Setting this field to zero initially will force the hardware to start sending
data one packet transmission period after setting the I bit. After the initialization of the
xxPCM channel, this field is used to remember which is the oldest not yet sent byte in
the TX xxPCM Circular Buffers associated with this xxPCM channel.
TX xxPCM Circular Buffer Size. “000” = 256 samples (512 bytes); “001” = 512
samples (1024 bytes); others = reserved.
Valid bit. When ‘0’, all “Assembly Event - Service xxPCM RTP Channel” will be
ignored, preventing xxPCM channel packets from being sent.
This field is reserved for future use and should always be set zero.
Pointer to a TX Silence Suppression structure. A value of 0000h indicates no silence
suppression is needed on this xxPCM channel. The pointer points to 32 byte
increments in SSRAM A.
Number of TDM bearers (i.e. TX xxPCM Circular Buffers) to be included in a packet.
This field is usually set to 1. It specifies the number of TX xxPCM Circular Buffers that
will be read for each frame that is sent, extracting a sample from each of them. This
field also defined the number of “Bearer x - Circular Buffer Base Address” extension
words appended to this structure.
Number of samples to assembled into a single packet at a given CODEC rate. The
total number of samples in packet is calculated as such: “Number of Bearers” *
“Samples per packet”.
Pointer to each TX xxPCM circular buffer that must be read in order to assemble a
packet. There must be one of these addresses per Bearer in the xxPCM channel.
This points to circular buffers in increments of 512 byte of addressing in SSRAM A.
For each bearer in this xxPCM channel, a single circular buffer base address must be
specified in one of these extension words. All xxPCM channels will have between 1
and 255 bearers, thus between 1 and 255 extension words.
Table 34 - Fields and Description
Zarlink Semiconductor Inc.
Definition