User's Manual
PCS3_HD_v01.000-03
Confidential / Preliminary
Page 46 of 101
2013-10-21
PCS3 Hardware Interface Description
3.9 Digital Audio Interface
125 µs
MSB
14
13
12
2
1
LSB
MSB
MSB
14
13
12
2
1
LSB
MSB
Table 12: Overview of PCM signal functions
Signal name on
SMT application
interface
Signal
configuration
inactive
1
Signal
direction:
Master
Signal
direction:
Slave
Description
PCM_FSC PD O I
Frame synchronization signal to/from
external codec
PCM_CLK PD O I Bit clock to/from external codec
1.
Inactive means no call, no tone generation and no external clock mode. PD = Pull down
The timing of a PCM short frame is shown in Figure 17. The timing for master and slave mode
is identical, except for the PCM_FSC and PCM_CLK signal direction (see Table 12).
PCM_CLK
PCM_FSC
PCM_OUT
PCM_IN
Figure 17: PCM timing short frame (External codec 2048KHz)
The timing of a PCM long frame for the additional 128kHz master mode is shown in Figure 18.
PCM_CLK
PCM_FSC
PCM_OUT
PCM_IN
1 LSB
1
LSB
MSB
MSB
14 13 8 7
14 13 8
7
2 1 LSB
2 1
LSB
MSB 14
MSB 14
Figure 18: PCM timing long frame (master, 128kHz)
Please note that PCM data is always formatted as 16-bit uncompressed two’s complement. Al-
so, all PCM data and frame synchronization signals are written to the PCM bus on the rising
clock edge and read on the falling edge.