PI 2 Design Pi 2 Media PI2AES, Hardware Reference Manual

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PI2Media PI2AES
Hardware Reference Manual – P0.1 - 3/27/2019
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3 3
3 OVERVIEW
OVERVIEW OVERVIEW
OVERVIEW
3.1 INTRODUCTION
The PI2AES, designed and manufactured by PI 2 Design, is a professional I/O Shield
designed to bring Professional Studio Grade Audio to the Raspberry PI
® family of
Single Board Computers. This low-cost Shield converts the Raspberry Pi ® I2S
Interface to High Definition Digital Audio Coax, OPTO and Balanced XLR.
The addition of Parallel I2S Output along with LVDS Differential over HDMI allows the
PI2AES to interface with virtually any High Performance DAC on the market.
The major features of the PI2AES are as follows:
•
FORM FACTOR – Raspberry Pi ® Shield Size w/40-Pin mating connector.
•
AES TRANSMITTER – The industry standard WM8804 converts the RPi I2S stream to AES3/SPDIF
formatted data at 24-Bit up to 192Khz Frame Rate
•
COAX OUTPUT – A 1:1 Isolation Transformer provides Bit Perfect Impedance Controlled Coaxial
Transmission of the Digital Audio Data via RCA Jack
•
SPDIF OPTICAL OUTPUT – Isolated Optical Transmitter Drives Consumer Level DAC and AVR
•
BALANCED OUTPUT – An RS-422 Transmitter coupled with a 1:1 Isolation Transformer allows
the transmission of balanced audio data via the Professional Audio Standard XLR Connector
•
BUFFERED I2S OUTPUT – Parallel Buffered I2S is available for direct short distance connection to
off-board D/A. Perfect for DIY use! I2C for control is also provided as well as 5V Regulated and Input
Voltage Rails.
•
DIFFERENTIAL I2S OUTPUT – A DS2063 Differential Transmitters is used to drive the I2S Bus over
a standard HDMI Connector. The Pinout is Selectable Between the PS Audio and Gustard Standards.
•
HIGH RESOLUTION CLOCKS – A pair of Ultra-Low Noise NDK NZ2520SD oscillators allow the
WM8804 to operate in non-PLL mode for the lowest possible noise.
•
ULTRA-LOW NOISE LDO’s – Ultra-Low Noise AP1155ADL LDO (30uV noise and 80dB PSRR) is
used to Supply the WM8804 Transmit Section, while an ADP150 (9uV noise and 70dB PSRR) and
the High-Resolution Clocks.
•
LOW NOISE PCB LAYOUT – Constructed with 4-layer Split Ground PCB with noise reduction
techniques refined from years of High-Speed Mixed-Signal Design work
3.2 BLOCK DIAGRAM
Refer to the following figure for a block diagram of the PI2AES Shield.