Comtrue CT-7301 User manual

Comtrue Inc.
CT-7301 demo board manual
Version 0.9 - 1 - 11/17/2014
Copyright © 2014 comtrue Inc. All rights reserved.
General Description
The CT-7301 is a single chip digital audio bridge with sample rate converter. It
supports the DSD I F and DoP in S PDIF channel. The chip also provides H W and
S W control modes.
Function:
8 digital audio input ports
Optical input x 1
Coaxial input x 4
I2S x 3
DSD x 1 (share with I2S input port 2)
3 digital audio output ports
S PDIF x 1 (parallel connect to optical and coaxial output)
I2S x 1
DSD x 1
H W control
Input channel select
Output Frequency select
PORx settings
S W control (I2C interface)
MCU on board (Arduino Nano)
External S W control port x 1

Comtrue Inc.
CT-7301 demo board manual
Version 0.9 - 2 - 11/17/2014
Copyright © 2014 comtrue Inc. All rights reserved.
Block Diagram
Board Diagram

Comtrue Inc.
CT-7301 demo board manual
Version 0.9 - 3 - 11/17/2014
Copyright © 2014 comtrue Inc. All rights reserved.
Description
Power
Input port
CT7301 demo board has 8 input ports. SPDIF I2S ports could receive 24 32 bit
data and DoP format data.
Port Function Note
0 SPDIF 0 Toslink
1 SPDIF 1 Coaxial
2 SPDIF 2 Coaxial
3 SPDIF 3 Coaxial
4 SPDIF 4 Coaxial
5 I2S
6 I2S
7 I2S DSD Depend by POR[1]
POR[1] = Low : Port 7 is I2S
POR[1] = High: Port 7 is DSD
There are two ways to select the input port.
You could directly change the settings of jumper J24 to select the input port, or
control the register to select the input port.
Example:
connect the upper two pins = 1
connect the lower two pins = 0
The setting of left picture is “001” ; input port is port 1.

Comtrue Inc.
CT-7301 demo board manual
Version 0.9 - 4 - 11/17/2014
Copyright © 2014 comtrue Inc. All rights reserved.
Output port
CT7301 demo board has 3 kinds of output, SPDIF(toslink x1, coaxtial x1), I2S, and
DSD.
Input signal SPDIF port I2S port DSD port
PCM data PCM PCM Mute
Non-PCM data Non-PCM Non-PCM Mute
Native DSD data
(enable D2P)
PCM PCM DSD
Native DSD data
(disable D2P)
DoP DoP DSD
DoP data
(enable D2P)
PCM PCM DSD
DoP data
(disable D2P)
DoP DoP DSD
H/W configuration setting
CT7301 H W configuration is controlled by PORx pins. You could modify the
settings by Jumper J21.
Connect the left two pins = 0.
Connect the right two pins = 1
PORx setting table:
Pin Name Description Function Table
POR[1]
POWER_ON_LATCH[1] = SEL_DSD_I2SZ_IN Select DSD or I2S-channel2 pins definition (pin 13,14,15)
0 = I2S channel 2
1 = DSD
POR[3:2]
POWER_ON_LATCH[3:2] = SEL_XTAL[1:0] Select Crystal frequency
00 = 12MHz

Comtrue Inc.
CT-7301 demo board manual
Version 0.9 - 5 - 11/17/2014
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Pin Name Description Function Table
01 = 11.2896MHz
10 = 12.288MHz
11 = 14.318MHz
POR[6:4]
POWER_ON_LATCH[6:4] = SEL_SRC_MODE[2:0] SRC mode selection
0 = Async SRC mode refer to external Fs signal.
1 = Async SRC mode refer to external Fs signal + SRC ratio (x1 2 4 8 16)
2 = Async SRC mode refer to external MCLK + SRC ratio (x1 2 4 8 16)
3 = Async SRC mode refer to internal PLL + frequency selector
4 = Sync SRC mode refer to input Fs + frequency selector
5 = Sync SRC mode refer to input Fs + SRC ratio(x1 2 4 8 16)
6, 7 = bypass SRC
Output Fs in SRC Ratio mode (refers to J25 settings)
Value base Fs=32KHz base Fs=44.1KHz base Fs=48KHz
0 x1 32KHz 44.1KHz 48KHz
1 x2 64KHz 88.2KHz 96KHz
2 x4 128KHz 176.4KHz 192KHz
3 x8 256KHz 352.8KHz 384KHz
4~7 x16 512KHz 705.6KHz 768KHz
Frequency select table (refers to J25 settings)
Value Output Fs Value Output Fs
0 32KHz 8 176.4KHz
1 32KHz 9 192KHz
2 44.1KHz A 256KHz
3 48KHz B 352.8KHz
4 64KHz C 384KHz
5 88.2KHz D 512KHz
6 96KHz E 705.6KHz
7 128KHz F 768KHz
POR[7]
POWER_ON_LATCH[7] = I2S_STDZ_LEFT I2S Rx Tx default format selection
0 = I2S standard format
1 = I2S left justified
POR[9:8]
POWER_ON_LATCH[9:8] = I2C_ID[1:0] I2C serial interface device ID selection
00 = 0x20
01 = 0x22
10 = 0x24

Comtrue Inc.
CT-7301 demo board manual
Version 0.9 - 6 - 11/17/2014
Copyright © 2014 comtrue Inc. All rights reserved.
Pin Name Description Function Table
11 = 0x26
Output Frequency control:
If the SRC mode is enabled, the output frequency is controlled by
OUT_FREQ[3:0]. OUT_FREQ[3:0] value could be modified by Jumper J25.
connect the upper two pins = 1
connect the lower two pins = 0
If the SRC mode is mode 0, 1 and 2, the external Fs Mclk signal should be
connect to ASRC_FSIN pin (J5).
S/W control
This demo board has a MCU slot and an external S W control port (J26). You
could put the Arduino Nano on the MCU slot to access CT7301. CT7301 also
could be controlled by the external MCU via the external S W control port.

Comtrue Inc.
CT-7301 demo board manual
Version 0.9 - 7 - 11/17/2014
Copyright © 2014 comtrue Inc. All rights reserved.
Sc ematics
Main block

Comtrue Inc.
CT-7301 demo board manual
Version 0.9 - 8 - 11/17/2014
Copyright © 2014 comtrue Inc. All rights reserved.
H W control block

Comtrue Inc.
CT-7301 demo board manual
Version 0.9 - 9 - 11/17/2014
Copyright © 2014 comtrue Inc. All rights reserved.
I O block

Comtrue Inc.
CT-7301 demo board manual
Version 0.9 - 10 - 11/17/2014
Copyright © 2014 comtrue Inc. All rights reserved.
MCU block

Comtrue Inc.
CT-7301 demo board manual
Version 0.9 - 11 - 11/17/2014
Copyright © 2014 comtrue Inc. All rights reserved.
Power block

Comtrue Inc.
CT-7301 demo board manual
Version 0.9 - 12 - 11/17/2014
Copyright © 2014 comtrue Inc. All rights reserved.