CM-42 Technical Description
PAGE 18 OF 38
SEM/CX-02:0076/DES A
2.3.4.2.1
Data Format
The CM-42 module implements a 13-bit PCM with the 13-bit data embedded in a 16-bit word as follows.
Each PCM word shall contain 16-bits D15 – D00. D15 – D03 is the 2´s-complement value of the 13-bit PCM, with
D15 as the sign bit. D15 is the MSB while D03 is the LSB. Note that the MSB is sent in first place. Ensure that the
read data from PCMDLD is right shifted three times and sign extended before being used
13-bit linear
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
MSB
LSB
x
x
x
Bit
Contents
D15 –
D03
Two complement of the 13-bit PCM.
D02 –
D00
Bits are undefined.
2.3.4.2.2
Timing
Timing shall be according to the following diagram (see Figure 6). The signals in the diagram shall be interpreted
according to the following relation.
Figure 6: PCM Timing Diagram
PCM_CLK
PCM_DLD
PCM_SYNC
t
CLK
t
SU(SYNC)
t
CLKH
PCM_ULD
14
13
12
t
CLKL
15
t
H(ULD)
t
SU(ULD)
0
t
H(SYNC)
15
14
13
12
0
t
PDLD
PCM_SYNC
t
SYNC
t
SYNCA
t
SYNCD
0
15
0
15
