MSC8113 Reference Manual, Rev. 0
20-22
Freescale Semiconductor
TDM Interface
before it is transmitted externally. The TDMxTFP[TCDBL] field provides an upper boundary on
the number of transmit bits that can be stored in TDM local memory. The transmit data latency is
defined as the time between when the data is read from the buffers mapped to the local bus and
when it is transmitted externally. Reducing the TDMxTFP[TCDBL] value reduces the transmit
data latency. However, writing the TDM local memory imposes more strict latency requirements
on the local bus. The maximum transmit data latency is calculated as maximum transmit data
latency = TCDBL / (TCS)
×
(transmit frame time).
When the TDM cannot transfer data from data buffers to TDM local memory, an underrun
occurs. When the TDM transmit local memory is empty, the TDMxTER[ULBE] bit (see
page 20-66) is set and the TDMxTIER[ULBEE] bit is also set, an error interrupt is generated.
This error should not occur during normal operation. It indicates that the TDM has not received
enough bandwidth on the local bus and therefore cannot read the data from the source memory
into TDM transmit local memory. The minimum latency is achieved when the RCDBL/TCDBL
field is clear (only 64 bits are stored in the TDM local memory). For example, the minimum
latency for a T1 application with 8 bits per channel and a frame length of 125
μ
s is equal to 1
μ
s.
T1 minimum latency= 64/8
×
125
μ
s.
20.2.6 Buffers Mapped on the Local Bus
Each receive or transmit data channel is stored in a different buffer mapped on the internal local
bus. This buffer can be located in the M1 memory of one of the SC140 cores or in the M2
memory, which is shared by all the SC140 cores.
20.2.6.1 Data Buffer Size and A/
μ
-law Channels
Data buffer size is identical for all receive channels belonging to a TDM module and is indicated
in the TDMxRDBS[RDBS] field. Data buffer size is also identical for all the transmit data
buffers and is indicated in the TDMxTDBS[TDBS] field (see page 20-51). An exception is the
A/
μ
-law channels (buffer size
×
2). When the TDMxRCPRn[RCONV] field (see page 20-58)
indicates that a channel is an A-law channel, the received 8 bits are converted into a 13-bit PCM
sample padded with three zeros on the right. This channel therefore occupies 16 bits per 8
received bits, essentially occupying double the size. When the TDMxRCPRn[RCONV] field
indicates that a channel is a
μ
-law channel, the received 8 bits are converted into a 14-bit PCM
sample padded with two zeros on the right. This channel also occupies 16 bits per 8 received bits,
essentially occupying double the size.
When the TDMxTCPRn[TCONV] field (see page 20-59) indicates that a channel is an A-law
channel, the transmitted 13 bits are converted into an 8-bit PCM sample. This channel therefore
occupies 16 bits (13 bits padded with three zeros at the right) per 8 transmit bits, essentially
occupying double the size. When the TDMxTCPRn[TCONV] field indicates that a channel is a
μ
-law channel, the received 14 bits are converted into an 8-bit PCM sample. This channel also
occupies 16 bits (14 bits padded with two zeros at the right) per 8 transmit bits, essentially
Summary of Contents for MSC8113
Page 1: ...MSC8113 Reference Manual Tri Core 16 Bit Digital Signal Processor MSC8113RM Rev 0 May 2008 ...
Page 20: ...MSC8113 Reference Manual Rev 0 xx Freescale Semiconductor Contents ...
Page 28: ...MSC8113 Reference Manual Rev 0 xxviii Freescale Semiconductor ...
Page 56: ...MSC8113 Reference Manual Rev 0 1 28 Freescale Semiconductor MSC8113 Overview ...
Page 76: ...MSC8113 Reference Manual Rev 0 2 20 Freescale Semiconductor SC140 Core Overview ...
Page 134: ...MSC8113 Reference Manual Rev 0 4 30 Freescale Semiconductor System Interface Unit SIU ...
Page 168: ...MSC8113 Reference Manual Rev 0 6 18 Freescale Semiconductor Boot Program ...
Page 180: ...MSC8113 Reference Manual Rev 0 7 12 Freescale Semiconductor Clocks ...
Page 260: ...MSC8113 Reference Manual Rev 0 8 80 Freescale Semiconductor Memory Map ...
Page 300: ...MSC8113 Reference Manual Rev 0 9 40 Freescale Semiconductor Extended Core ...
Page 304: ...MSC8113 Reference Manual Rev 0 10 4 Freescale Semiconductor MQBus and M2 Memory ...
Page 308: ...MSC8113 Reference Manual Rev 0 11 4 Freescale Semiconductor SQBus ...
Page 590: ...MSC8113 Reference Manual Rev 0 17 46 Freescale Semiconductor Interrupt Processing ...
Page 614: ...MSC8113 Reference Manual Rev 0 18 24 Freescale Semiconductor Debugging ...
Page 622: ...MSC8113 Reference Manual Rev 0 19 8 Freescale Semiconductor Internal Peripheral Bus IPBus ...
Page 724: ...MSC8113 Reference Manual Rev 0 21 32 Freescale Semiconductor UART ...
Page 920: ...MSC8113 Reference Manual Rev 0 25 150 Freescale Semiconductor Ethernet Controller ...
Page 1171: ...MSC8113 Reference Manual Rev 0 Freescale Semiconductor C 61 EF wait_rts P 01077FFC 9F rts 71 ...
Page 1172: ...MSC8113 Reference Manual Rev 0 C 62 Freescale Semiconductor MSC8113 Boot Code ...
Page 1202: ...MSC8113 Reference Manual Rev 0 Index 30 Freescale Semiconductor Index ...