User's Manual

Bluegiga Technologies Oy
Page 29 of 52
Figure 20: GCI Interface
The start of frame is indicated by the rising edge of PCM_SYNC and runs at 8kHz.
14.2.2 Slots and Sample Formats
BT111 receives and transmits on any selection of the first 4 slots following each sync pulse. Slot durations
are either 8 or 16 clock cycles:
 8 clock cycles for 8-bit sample formats.
 16 clock cycles for 8-bit, 13-bit or 16-bit sample formats.
BT111 supports:
 13-bit linear, 16-bit linear and 8-bit μ-law or A-law sample formats.
 A sample rate of 8ksps.
 Little or big endian bit order.
 For 16-bit slots, the 3 or 8 unused bits in each slot are filled with sign extension, padded with zeros or
a programmable 3-bit audio attenuation compatible with some codecs.