Iancanada IsolatorPi III Galvanic Insulation Module User Guide

Iancanada IsolatorPi III Galvanic Insulation Module

Specifications

• Manufacturer: IanCanada.ca
• Power Input: 3.3V-5V DC
• Power Consumption: Around 100mA
• GPIO Connector: 40PIN isolated GPIO connector
• Output: Isolated and regulated 3.3V 200mA DC output

Product Usage Instructions

1. Power Connection:
   Connect a 3.3V-5V DC power supply to J1 for the IsolatorPi III to operate. Alternatively, power it from GPIO J6.

2. GPIO Connector:
   Use the 40PIN isolated GPIO connector J6 for various connections such as power supply, I2C bus, I2S output, ground, etc.

3. RPi GPIO Connection:
   Connect J4 to access GPIOs for non-analog devices while preserving isolation with audio cards.

4. Slave/Master Mode Selection:
   Set jumper settings J12 and J13 for slave or master mode selection to determine how I2S signals are generated.

5. DoP to Native DSD Decoding:
   Install the DoP decoder daughter board into J8 to enable conversion of DoP to native DSD signals when playing DSD music files.

Frequently Asked Questions (FAQ):

• Q: Can the IsolatorPi III be powered from GPIO J6 instead of J1?
  A: Yes, you can power the IsolatorPi III from GPIO J6 as it is directly connected to J1.

IsolatorPi III
User’s Guide
IanCanada.ca

Description

IsolatorPi III is a HAT board that provides galvanic isolation for I2S/DSD/DoP signals, I2C bus, some GPIO pins and power between the RaspberryPi and the digital audio boards. It prevents transmission of RaspberryPi’s EMI noise via ground and signal connections over GPIO.
IsolatorPi III is an upgrade version over IsolatorPi II. It uses a 5KV higher grade isolator chip and a real physical isolation gap to improve isolation performance. Some IsolatorPi II un-useful functions and circuits were also removed to optimize the PCB layout for better isolation.
Preventing that noise from getting into your audio boards allows them to work better. AND with lower noise on the ground, when you introduce better power supplies and lower jitter clocks for your audio cards, the positive effects will be enhanced.

Features and Specifications

• 150MHz 5KV high performance digital isolator, 768KHz I2S and DSD512 capable.
• Physical PCB gap slot to ensure the best possible isolation space
• Bi-directional architecture works with audio cards in both slave clock and master clock modes.
• Ready for native DSD output using companion DoP decoder in on-board socket.
• Isolated I2C bus for audio card configuration and control.
• Has an additional 40Pin non-isolated GPIO connector. With which, we can connect the possible MonitorPi/Pro, ESS DAC controller, IR receiver, the rotary encoder and many others to RPi. The good thing is that all of those devices will become 100% isolated from audio devices on top of the IsolaorPi III. DSD signals will also be applied to this non-isolated GPIO when the DoP decoder daughter board is installed.
• Needs no device driver and/or overlay. Works in transparent mode.
• Suitable for most Raspberry Pi audio cards such as DAC HATs, S/PDIF Adapter HATs, I2S Re-clocker HATs and many other RPi HiFi applications.
• Supports 502DAC Pro, Hifiberry Digi Pro +, and all other WM8804 based applications in master clock mode;
• Great to Upgrade a TransportPiDigi, a FifoPiMa or an ESS DAC running at non-sync mode

Block diagram

Layout and Dimensions (in mm)

Connectors
J1: 3.3V-5V DC clean side power input
A 3.3V-5V DC power supply must be connected to this terminal for the IsolatorPi III to operate. This is regulated to 3.3v to run the IsolatorPi III and is also passed to the connected audio board via the RPi GPIO (J4 and J6) power pins. When used with the optional DoP decoder daughter board, IsolatorPi III consumes around 100mA current.
J1 is directly connected to pin2 and pin4 of J6, so alternatively you can also power it from GPIO J6 rather than J1. The clean side power is completely separate from the Raspberry Pi’s power and ground.

J6: 40PIN isolated GPIO connector

as DACs. This is a pass-through of the power supply connected at J1 and the available voltage and current are set by that supply. It is entirely isolated from the RPi 5V.
1, 17| 3.3V| Isolated and regulated 3.3V 200mA DC output.
3| I2CDA| Isolated I2C bus to configure and control audio cards
5| I2CCL
12| SCK/BCK| Isolated I2S or DSD output
35| LRCK/DL
40| DATA/DR
6,9,14,20,25,30,34,39| GND| Isolated ground
15,22| PULL UP| Pull up to 3.3Vcc with 4.7K resistor, reserved for some audio cards
29,31| XO selection| Isolated GPIO5 and GPIO6
All other pins| NC| Not connected

J4: Non-isolated 40PIN RPi GPIO
This connection parallels all power and signal connections from the input 40PIN GPIO connector (pin to pin connected). This provides access to GPIOs for applications such as IR receivers, rotary encoders and other non-analog devices while preserving isolation with the audio cards. You can power the RPi through this connector by connecting 5v to pin 5 (and/or pin 2) and ground to pins 6 (and/or pins 9,14,20,25,30,34,39).

J3: RPi GPIO socket
Connect to the source SBC’s (RaspberryPi or ODROID) 40PIN GPIO connector.

Jumper settings
J12 and J13: Slave/Master mode selection
In slave mode(default), the RPi generates the three I2S (SCK, LRCK and DATA) signals using its internal clock. These I2S signals are fed into the audio card through the IsolatorPi III.
In master mode, the audio card contains two dedicated audio clock oscillators (XO) that are used to generate the SCK and LRCK of I2S signals. These two I2S clock signals are fed back into the RPi through the IsolatorPi III. The RPi uses these two I2S clock signals to generate the DATA signal instead of using its internal clock.

Because the RPi internal clock is not dedicate audio clock

AND must be converted to the audio clock frequencies by internal PLL and CTC, it is a very high jitter clock. Audio cards that operate in master mode can produce better quality results when they use high quality / low jitter clocks and feed high quality / low jitter SCK and LRCL I2S signals to the RPi. Using the IsolatorPi III with an audio board operating in master mode can further improve the sound quality by preventing transmission of EMI noise via the RPi ground AND by powering the audio card (and isolated side of the IsolatorPi III) using a separate power supply.
Audio cards operating in master mode typically require dedicated Linux device drivers. Please see the audio card’s user manual for details.

DoP to native DSD decoding
Conversion of DoP to native DSD can be enabled using the DoP decoder daughter board into J8. With this card installed, the IsolatorPi III will output native DSD signals when playing a DSD music file. Most of current software for RPi can support DoP. For this to work, the music player on the RPi must be set to enable the DoP output function.

 LED indicators

Typical applications

1. Upgrade a TransportPiDigi with an Isolator

   • IsolatorPi III settings:

   • J13: 1-2, 3-4 short

   • J12: All open

   • TransportPi Digi settings

   • All default
     Power connections

   • Connecting the 3.3V to IsolatorPi III J1 only

   • Configurations

   • TransportPi Digi

   • IsolatorPi III

   • PurePi power supply

   • RaspberryPi

   • MonitorPi or MonitorPi Pro (optional)

   • Note: To upgrade any WM8804/5 based Transport/DAC with an Isolator, you can follow this application for the configuration

2. Upgrade A FifoPiMa application with an Isolator

   • IsolatorPi III settings: J13: 1-2, 3-4 short
   • J12: All open
   • FifioPi Ma settings
   • All default (J4 open)
   • Power connections Connecting the 3.3V to both IsolatorPi III J1 and FifoPiMa J5
   • Configurations FifoPiMa
   • IsolatorPi III
   • PurePi power supply RaspberryPi
   • Note: To upgrade any
   • PCM5122 based Transport/DAC with an Isolator, you can follow this application for the configuration

3. Upgrade an Ian ESS DAC with an Isolator

   • IsolatorPi III settings:
   • J13: All open
   • J12: 1-2, 3-4 short
   • ESS DAC settings
   • All default (Local clock
   • mode)
   • Power connections Connecting the 3.3V to
   • both IsolatorPi III J1 and
   • DAC 3.3V power input
   • Configurations
   • ES9038Q2M Dual Mono
   • I/V board
   • IsolatorPi III
   • PurePi power supply RaspberryPi
   • MonitorPi Pro or ESS controller

4. Remote isolated I2S/DSD over HDMI network streamer project

   • IsolatorPi III settings: J13: All open
   • J12: 1-2, 3-4 short
   • HdmiPi MkII settings Jumper 1,2,3: ON Jumper 4: OFF
   • Power connections Connecting the 3.3V to IsolatorPi III J1 only
   • Configurations
   • HdmiPi MkII
   • IsolatorPi III
   • PurePi power supply RaspberryPi
   • Optional MonitorPi or Pro

5. Upgrade an Audiophoincs I-Sabre ESS DAC with an isolator and battery power supply

   • IsolatorPi III settings: J13: All open
   • J12: 1-2, 3-4 short
   • I-Sabre settings
   • All default
   • Power connections Connecting the 3.3V to IsolatorPi III J1 only
   • Configurations
   • I-Sabre ES9038Q2M DAC IsolatorPi III
   • PurePi power supply RaspberryPi
   • MonitorPi Pro as controller

6. Install a DoP decoder to the IsolatorPi III to enable the native DSD over GPIO

   • IsolatorPi III settings: J13: All open
   • J12: 1-2, 3-4 short
   • DoP board settings All default

Application Notes and Tips

1.  Validate that both your hardware and software functions as expected AND produces audio output BEFORE you install the IsolatorPi III between the RPi and the audio card(s). If you do not do this, debugging any problems will be much more difficult.
2. IsolatorPi III by itself MAY NOT improve sound quality. BUT the ground isolation will enhance the effects of a good audio-quality power supply connected to the Isolator Pi and audio card and use of good clocks.
3. DO NOT make any link or connection between the input side of the IsolatorPi III (non-isolated GPIO) and output side (isolated GPIO). If you do the ground isolation is defeated and no benefit is produced.
4. BE VERY CAREFUL on the orientation of jumpers. Double and triple check before applying power. Incorrectly oriented jumpers can damage the IsolatorPi III.
5.  ONLY change the jumpers on J8 when the IsolatorPi III will be used with a DoP decoder daughter board.

© 2024 IanCanada. The firmware code embedded in the IsolatorPi board is the property of Ian Jin. You are granted a non-exclusive, non-transferable, non- sublicensable, royalty-free right to use the IsolatorPi board solely for your own, non-commercial purposes. You may not distribute, sell, lease, transfer, modify, adapt, translate, reverse engineer, prepare derivative works of, decompile, or disassemble the software provided. All rights reserved.

References

• IanCanada

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