DSP16411 Datasheet, PDF (171/316 Pages) Agere Systems – DSP16411 Digital Signal Processor

Data Sheet
May 2003
DSP16411 Digital Signal Processor
4 Hardware Architecture (continued)
4.16 Serial Interface Unit (SIU) (continued)
4.16.12 Channel Mode—32 Channels or Less in
Two Subframes or Less
Compared to frame mode, channel mode provides for
channel selectivity with minimal core overhead at the
expense of channel density. For input, this mode is
selected if the following conditions are met:
! The IFRAME field (SCON1[7]—see Table 104 on
page 186) is cleared.
! The ISFIDV_E field (SCON3[2]—see Table 106 on
page 188), the ISFIDV_O field (SCON3[5]), or both
are set.
For output, channel mode is selected if the following
conditions are met:
! The OFRAME field (SCON2[7]—see Table 104 on
page 186) is cleared.
! The OSFIDV_E field (SCON3[10]), the OSFIDV_O
field (SCON3[13]), or both are set.
In this mode, the SIU processes a maximum of
32 channels within a given frame. The maximum
frame size is 128 channels. The IFLIM[6:0] field
(SCON1[6:0]—Table 104 on page 186) for input and
the OFLIM[6:0] field (SCON2[6:0]—Table 105 on
page 187) for output define the number of channels in
the frame structure.
To assist with channel selection, both input and output
frames are divided into eight subframes: four even (0,
2, 4, 6) and four odd (1, 3, 5, 7). The SIU can enable
only one even and one odd subframe at any one time.
Each subframe contains 16 channels¹ that can be indi-
vidually enabled. Figure 49 shows a 128-channel
frame and the relationship between frames, subframes,
and logical channels. Table 94 on page 172 specifies
the association of channel numbers to even and odd
subframes.
SYNC
Channel Mode on a 128-Channel Frame
128-CHANNEL FRAME
〈I,O〉FLIM = 0x7F
〈I,O〉FRAME = 0x0
; DEFINE AS 128-CHANNEL FRAME
; TRANSFER ONLY SELECTED CHANNELS
DATA
8 SUBFRAMES PER TDM FRAME
16 CHANNELS PER SUBFRAME
EVEN
ODD
EVEN
ODD
EVEN
ODD
EVEN
ODD
SUBFRAME SUBFRAME SUBFRAME SUBFRAME SUBFRAME SUBFRAME SUBFRAME SUBFRAME
[0:15]
[16:31]
[32:47]
[48:63]
[64:79]
[80:95]
[96:111] [112:127]
SUBFRAME 2
SUBFRAME 5
00
1
2
13
14
15
〈I,O〉SFID_E = 1
; SUBFRAME 2 SELECTED
0
〈I,O〉SFIDV_E = 1
; ALLOW INDIVIDUAL CHANNEL SELECTION
〈I,O〉SFVEC_E = 0xFFFF ; ALL 16 CHANNELS ACCESSIBLE
OSFMSK_E = 0x7FF9 ; MASK ALL OUTPUT CHANNELS
; EXCEPT 15, 2, 1
16 BITS PER CHANNEL
1
2
13
14
15
〈I,O〉SFID_O = 2
; SUBFRAME 5 SELECTED
〈I,O〉SFIDV_O = 1
; ALLOW INDIVIDUAL CHANNEL SELECTION
〈I,O〉SFVEC_O = 0xFFFF ; ALL 16 CHANNELS ACCESSIBLE
OSFMSK_O = 0xBFFD ; MASK ALL OUTPUT CHANNELS
; EXCEPT 1 AND 14
ACTIVE CHANNELS
MASKED CHANNELS
CHANNEL DATA BITS
CHANNEL DATA BITS
0
1
2
13
14
15
〈I,O〉ISIZE = 1 ; 16-BIT CHANNELS
〈I,O〉MSB = 1 ; MSB SHIFTED FIRST
Figure 49. Channel Mode on a 128-Channel Frame
1. It is assumed that for channel mode, the number of channels per frame as determined by the IFLIM[6:0] and OFLIM[6:0] fields is evenly
divisible by 16. This results in exactly 16 channels per subframe. If the number of channels per frame is not evenly divisible by 16, the last
subframe is a partial subframe of less than 16 channels. If this is the case and if interrupts are programmed to occur on subframe bound-
aries (see Figure 51 on page 178), then an interrupt is not generated for the partial subframe.
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