User's Manual

NEMO Bluetooth Radio Module
Solutions for a Real Time World Datasheet
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Copyright Unigen Corporation, 2008
Figure 17: PCM slave Timing Short Frame Sync
PCM CLK and PCM SYNC Generation
NEMO has two methods of generating the PCM CLK and PCM SYNC in master mode:
• Generating signals by Direct Digital Synthesis (DDS) from internal 4MHz clock. Using this
mode limits BT_PCM_CLK_P to 126, 256 or 512kHz, and BT_PCM_SYNC_P to 8kHz.
• Generating these signals by DDS from an internal 48MHz clock (which allows greater range
of frequencies to be generated with low jitter but consumes more power). This method is
selected by setting bit 48M_PCM_CLK_GEN_EN in the PSKEY_PCM_CONFIG32 key. When in
this mode and with long frame sync, the length of the BT_PCM_SYNC_P can either be8 or
16 cycles of BT_PCM_CLK_P, determined by LONG_LENGTH_SYNC_EN bit in the
PSKEY_PCM_CONFIG32 key.