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Apalis Carrier Board Design Guide
Toradex AG l Altsagenstrasse 5 l 6048 Horw l Switzerland l +41 41 500 48 00 l
l
Page | 58
It is recommended to place 22R series resistors to the signal lines. Place these resistors close to the
signal outputs
Figure 52: HDA Reference Schematic
2.20.3 Unused Digital Audio Interface Signal Termination
Unused digital audio interface signals can be left unconnected.
2.21 S/PDIF (Sony-Philips Digital Interface I/O)
S/PDIF is a widely used digital interface for multi-channel audio. For consumer audio equipment,
there are two variants of the physical layer available. The first variant uses 75
Ω
electrical coaxial
cables and RCA connectors. The second variant uses fiber optic cable with TOSLINK connectors.
2.21.1 S/PDIF Signals
Apalis
Pin
Apalis
Signal Name
I/O
Type
Power
Rail
Description
215
SPDIF1_OUT
O
CMOS
3.3V
Serial data output
217
SPDIF1_IN
I
CMOS
3.3V
Serial data input
Table 33: S/PDIF Signals
2.21.2 Reference Schematics
For the fiber optic variant, both the transmitter and receiver is required. There are TOSLINK
connectors available with built-in transmitters and receivers. The coaxial signal is specified as low
voltage signal (max. output 0.6V, min input 0.5V) while the Apalis S/PDIF signals are 3.3V logic
level. Therefore, level shifters are required. The following reference schematic shows a very simple
solution. Some projects may require a galvanically isolated solution
MM70-314-310B1
Apalis - Digital Audio
22 of 25
DAP1_MCLK
194
DAP1_SYNC
204
DAP1_BIT_CLK
200
DAP1_D_OUT
196
DAP1_D_IN
202
DAP1_RESET#
198
X1V
22R
RA99B
22R
RA99C
22R
RA99D
DAP1_D_OUT
DAP1_D_IN
DAP1_SYNC
DAP1_BIT_CLK
DAP1_RESET#
DAP1_3.3V_DV
DAP1_5V_AV
10uF
6.3V
C252
100nF
16V
C251
1uF
16V
C250
GND
GND
DAP1_HDA_SIDESURROUND_R
DAP1_HDA_SIDESURROUND_L
DAP1_HDA_LOW_FREQ
DAP1_HDA_CENTER
DAP1_HDA_MIC2_R
DAP1_HDA_MIC2_VREF
DAP1_HDA_MIC2_L
DAP1_HDA_LINE2_R
DAP1_HDA_LINE2_VREF
DAP1_HDA_LINE2_L
DAP1_HDA_FRONT_R
DAP1_HDA_FRONT_L
DAP1_HDA_LINE1_R
DAP1_HDA_LINE1_VREF
DAP1_HDA_LINE1_L
DAP1_HDA_MIC1_VREF_R
DAP1_HDA_MIC1_R
DAP1_HDA_MIC1_VREF_L
DAP1_HDA_MIC1_L
DAP1_HDA_SURROUND_VREF
DAP1_HDA_SURROUND_L
DAP1_HDA_SURROUND_R
R209
20K
GND
DAP1_HDA_J DREF
DAP1_HDA_SENSE_A
DAP1_HDA_SENSE_B
ALC888-GR
DV_CORE
1
GPIO_0
2
GPIO_1
3
DV_SS
4
SDATA_OUT
5
BIT_CLK
6
DV_SS
7
SDATA_IN
8
DV_DD
9
SYNC
10
RESET#
11
PC_BEEP
12
SENSE_A/SRC_B
13
PORT_E_L
14
PORT_E_R
15
PORT_F_L
16
PORT_F_R
17
CD_L
18
CD_GND
19
CD_R
20
PORT_B_L
21
PORT_B_R
22
PORT_C_L
23
PORT_C_R
24
AV_DD
25
AV_SS
26
VREF_FILT
27
MIC_1_BIAS_L
28
V_REF_C
29
MIC_BIAS_F
30
V_REF_E
31
MIC_1_BIAS_R
32
SENSE_B/SRC_A
34
PORT_D_L
35
PORT_D_R
36
V_REF_A
37
AV_DD
38
PORT_A_L
39
JDREF
40
PORT_A_R
41
AV_SS
42
PORT_G_L
43
PORT_G_R
44
PORT_H_L
45
PORT_H_R
46
S/PDIF_IN/GPIO_1
47
S/PDIF_OUT
48
NC
33
SID E-R
SID E-L
LOW FR EQU
C EN TER
SU R R _R
SU R R _L
FR ON T_L
FR ON T_R
LIN E1_L
LIN E1_R
LIN E2_R
LIN E2_L
MIC 1_L
MIC 1_R
MIC 2_R
MIC 2_L
IC28
AGND2
DAP1_F_HEAD_PRES#
GND
2A
120R@100MHz
L33
10uF
10V
C248
100nF
16V
C247
100nF
16V
C246
2A
120R@100MHz
L32
10uF
10V
C245
100nF
16V
C244
2A
120R@100MHz
L31
10uF
10V
C243
100nF
16V
C239
10uF
10V
C240
100nF
16V
C238
2A
120R@100MHz
L30
4.7uF
10V
+
C241
TIED TOGETHER AT ONE POINT ONLY
3.3V_SW
AGND2
22R
RA26A
22R
RA26B
10uF
10V
C242
10uF
10V
C249
TP18
DAP1_PC_BEEP
DAP1_CD_L
DAP1_CD_GND
DAP1_CD_R
TP19
TP20
TP33
TP34
DAP1_S/PDIF_IN
10uF
10V
C284
GND
5V_SW
DAP1_S/PDIF_OUT
NA
NA
NA
NA
NA
0R
R23
NA
DAP1_D_OUT
DAP1_D_IN
DAP1_BIT_CLK
DAP1_SYNC
DAP1_RESET#
TP35
UNDER OR NEAR THE CODEC