miniDSP Ltd, Hong Kong / www.minidsp.com / Features and specifications subject to change without prior notice 9
2.2 USB (AUDIO + DC POWER)
The UMA-8 is USB self powered. A single USB connection to your PC/Mac will suffice to provide power to the
unit and stream bidirectional audio simultaneously.
To record audio from the UMA-8, connect the USB port of the UMA-8 to a USB 2.0 port on your computer using
the supplied cable. The UMA-8 should also be connected for initial driver installation under Windows.
2.3 I2S EXPANSION HEADER PINOUTS
Headers J3 is provided for connection of I/O circuitry via I2S. The pinouts are shown in Table 1.
In the current firmware, only J3.1 / I2S_OUT0 is enabled as “SPEAKER OUTPUTS”
Table 1. J3 expansion header pinout
2.4 I2S OVERVIEW
I2S, or Inter IC Sound, is an electrical serial bus used to interface digital audio devices at the chip and circuit
board level. An I2S interface consists of up to three clocks, and a data line for each pair of channels. There are
three types of clock:
MCLK The master clock that the UMA-8 uses internally. This clock is always provided as an output by
the UMA-8, and connected circuitry can choose whether or not to use it.
LRCLK The frame synchronization clock, also known as the word clock. This clock is equal to the
sampling frequency (Fs) of the audio signal.
BCLK The bit clock (also known as shift clock or system clock). This is always equal to 64 x Fs.
Table 2. I2S clock ratios
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