User's Manual

FLC-BTM403 Datasheet
Flaircomm Microelectronics Confidential
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Figure 7: Multi-Slot Operation with Two Slots and 8-bit Companded Samples
4.3.5 GCI Interface
The module is compatible with the General Circuit Interface (GCI), a standard synchronous 2B+D
ISDN timing interface. The two 64Kbps B channels can be accessed when this mode is configured.
Figure 8: GCI Interface
The start of a frame is indicated by the rising edge of PCM_SYNC and runs at 8kHz. With the
module in slave mode, the frequency of PCM_CLK can be up to 4.096MHz.
4.3.6 Slots and Sample Formats
The module can receive and transmit on any selection of the first four slots following each sync
pulse. Slot durations can be either 8 or 16 clock cycles. Durations of 8 clock cycles may only be
used with 8-bit sample formats. Durations of 16 clocks may be used with 8-bit, 13-bit or 16-bit
sample formats. The module supports 13-bit linear, 16-bit linear and 8-bit ยต-law or A-law sample
formats. The sample rate is 8k samples/s. The bit order may be little or big endian. When 16-bit slots
are used, the 3 or 8 unused bits in each slot may be filled with sign extension, padded with zeros or a
programmable 3-bit audio attenuation compatible with some Motorola CODECs.