EMC12 ETC2 [List of Unclassifed Manufacturers], EMC12 Datasheet - Page 16

• Manufacturer Part Number: EMC12
• Description: Audio Interface for the EmPack System
• Manufacturer: ETC2 [List of Unclassifed Manufacturers]

1.3
Serial data passing between resources in an EmPack system are routed through 6 time-division-
multiplexed (TDM) buses They are called buses A, B, C, D, E and F. Each contains a data signal and a
valid signal. The Table below shows how LTDM lines are allocated among the 6 buses.
All 6 buses run synchronously at the same bit clock rate, with identical slot definition, frame duration and
frame sync pulse. The buses are connected to the serial port of each DSP. The TDM system operates
independently of the parallel I/O system.
Frames of data are passed through each serial TDM bus. The number of slots per frame is fixed at 128.
Each time slot has a fixed length of 8 bits. A buffered version of LCLK (SLCK) is used as the TDM bit
clock. The LFSYNC- signal is used to indicate frame boundary. It goes low on the falling edge of
LCLK for one LCLK period and the frame boundary falls within that pulse.
The TDM subsystem also has the concept of “Superframe” or “Multiframe” timing. The signal,
LMSYNC is a high active pulse that lasts for one TDM frame with transitions on a frame boundary. The
number of frames per Multiframe is controlled by the foundation board using the API function,
EmSetTdmMode . The LMSYNC signal is connected to the SY pin of the DSP. A DSP program can
test the state of the SY pin (using the sys flag to test if LMSYNC is high and the syc flag to test if
LMSYNC is low). A DSP program can synchronize its serial input and output to the TDM frames by
testing for a transition on the LMSYNC signal.
1.3.1 TDM Connections
The interconnection of TDM data to various resources in the system is dynamically controlled by the
contents of the TDM map. For each time slot, a set of control words in the map determines the source
and destination(s) of the data on each TDM bus. The control words are recycled in every TDM frame.
For the EMC12 mezzanine, eight control words are used to establish connection for each time slot.
Tables 1- 13, 1-14, and 1-15, below, show the format of the control words.
09 Jan 2006
EMC12 TDM
Table 1-12: LTDM[0-11] Signal Allocation
Communication Automation Corporation
TDM BUS
A
B
C
D
E
F
EMC12 Hardware Reference Manual
TDM Data
LTDM0
LTDM1
LTDM4
LTDM5
LTDM8
LTDM9
TDM Valid
LTDM2
LTDM3
LTDM6
LTDM7
LTDM10
LTDM11
1-12