# Allo DigiOne board

**URL:** <https://community.roonlabs.com/t/allo-digione-board/18564>\
**Category:** Raspberry Pi\
**Created:** [January 19, 2017, 4:47pm UTC](https://community.roonlabs.com/t/allo-digione-board/18564 "2017-01-19T16:47:53Z")\
**Posts on this page:** 1\
**Showing post:** 128

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**Author:** ![allo.com](https://community.roonlabs.com/letter_avatar/allo.com/32/5_5575768a8748004e209b776fc1b2916d.png) [@allo.com](https://community.roonlabs.com/u/allo.com)\
**Post date:** [July 6, 2017, 7:33am UTC](https://community.roonlabs.com/t/allo-digione-board/18564/128 "2017-07-06T07:33:11Z")

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Just a quick explanation on what DigiOne really is 🙂

Master codec . (basically it means that RPI is not using its jittery clocks…the WM8805 (dirty side) has a clock (on clean side separated by a galvanic digital isolator) and RPI only sends the DATA to it on each clock (bclk/lrclk)

Once data is received the WM8805 makes the spidif stream . (still dirty side)

Spidif stream passes the isolator barrier (picking up jitter but removing any HF noise)

Now on the clean side… you have the clocks and 2 set of flip flops(pay attention to fact there are 2 sets). Since the spidif stream is made using the same clocks…there are no buffer over/under runs (one time domain)

On first flipflops…we realign the data on clean MCLK …therefore the MCLK jitter = spidif jitter (+ extremely low extra jitter from flip flop in the 0.0xps) = 0.4ps

On second FF…we take care of a phenomenon called metastability [https://en.wikipedia.org/wiki/Metastability\_in\_electronics](https://en.wikipedia.org/wiki/Metastability_in_electronics) (no one is doing that)

So you see…what DigiOne really is…is a master codec with digital/electrical/ground isolation from RPI AND wm8805 and a reclocker (with metastability taken into account)

Simple.

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