PxWy = Phase x Word y
D(R/X)
FS(R/X)
P2W12
P2W11
P2W10
P2W9
P2W8
P2W7
P2W6
P2W5
P2W4
P2W3
P2W2
P2W1
P1W1
ÁÁ
ÁÁ
ÁÁ
ÁÁ
20 bits
16 bits
1-bit data delay
Figure 15-11. Implementing the AC97 Standard With a Dual-Phase Frame
• (R/X)PHASE = 1: Dual-phase frame
• (R/X)FRLEN1 = 0000000b: 1 word in phase 1
• (R/X)WDLEN1 = 010b: 16 bits per word in phase 1
• (R/X)FRLEN2 = 0001011b: 12 words in phase 2
• (R/X)WDLEN2 = 011b: 20 bits per word in phase 2
• CLKRP/CLKXP= 0: Receive data sampled on falling edge of internal CLKR / transmit data clocked on rising
edge of internal CLKX
• FSRP/FSXP = 0: Active-high frame-sync signal
• (R/X)DATDLY = 01b: Data delay of 1 clock cycle (1-bit data delay)
shows the timing of an AC97-standard data transfer near frame synchronization. In this figure,
individual bits are shown on D(R/X). Specifically, the figure shows the last two bits of phase 2 of one frame and
the first four bits of phase 1 of the next frame. Regardless of the data delay, data transfers can occur without
gaps. The first bit of the second frame (P1W1B15) immediately follows the last bit of the first frame (P2W12B0).
Because a 1-bit data delay has been chosen, the transition on the frame-sync signal can occur when P2W12B0
is transferred.
PxWyBz = Phase x Word y Bit z
Á
Á
Á
Á
P2W12B0
P2W12B1
MDRA
P1W1B15
P1W1B12
P1W1B13
P1W1B14
MFSRA
MCLKRA
1-bit data delay
Figure 15-12. Timing of an AC97-Standard Data Transfer Near Frame Synchronization
15.2.4.5 McBSP Reception
This section explains the fundamental process of reception in the McBSP. For details about how to program the
McBSP receiver, see
show how reception occurs in the McBSP.
shows the physical path
is a timing diagram showing signal activity for one possible reception scenario. A
description of the process follows the figures.
ÁÁÁÁ
ÁÁÁÁ
ÁÁÁÁ
ÁÁÁ
ÁÁÁ
ÁÁÁ
DR
RSR[1,2]
Expand
ÁÁÁÁ
ÁÁÁÁ
ÁÁÁÁ
RBR[1,2]
DRR[1,2]
DRR[1,2]
RBR[1,2]
To CPU or
DMA controller
justify and bit fill
or
A.
RSR[1,2]: Receive shift registers 1 and 2
B.
RBR[1,2]: Receive buffer registers 1 and 2
C.
DRR[1,2]: Data receive registers 1 and 2
Figure 15-13. McBSP Reception Physical Data Path
Multichannel Buffered Serial Port (McBSP)
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
TMS320x2806x Microcontrollers
887
Copyright © 2022 Texas Instruments Incorporated
Summary of Contents for TMS320 2806 Series
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