Asynchronous I2S FIFO project, an ultimate weapon to fight the jitter

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roderickvd

roderickvd

Member
Joined 2015
Really interested in the StationPi + FifoPi combo. I am at a bit of a loss though about providing 5V "audio power" to the FifoPi. How should it be done?

The StationPi PCB spells out "NO CONNECT FOR FiFoPi" right next to J5. At the same time the StationPi Q&A states:

3. If a FifoPi is installed to the J2 or J7, how to power the FifoPi Pi side?

You can power FifoPi Pi side from J5 of the StationPi (recommended) or from J3 of the FifoPi.
Click to expand...

(emphasis mine)

This seems contradictory to me or am I misunderstanding?
 
W

wcwc

Member
Joined 2011
I plan to only use two power supplies for my pi/fifopi/transportpi stack on the station pi. I was going to run power for the pi and FIFOpi dirty side from the same feed. Have to feed wires to both sides of the StationPi to get it to work this way. Then use another feed for the clean side of the FIFOpi and the TransportPi (need to run to the power connector on the FIFOpi to get it to work). That is the way I understand the power connections to work on the StationPi. No power is being transferred between the sides of the StationPi on the GPIO header.
 
K

kirks

Member
Joined 2015
iancanada said:
@ A123

You can use 3.3V rather than the 5V at the audio side if you use a FifoPi.
I built my own DAC with StationPi and LifePO4 MKIII by this way.

Regards,
Ian
Click to expand...

Ian
I am still unclear on powering the FifoPi when mounted on a StationPi. Do I need to power both 3.3V into J5 on StationPi and 3.3V into J5 on FifoPiQ3? Or, do i just apply 3.3V to one of those connections?
Also the instructions indicate grounding FifoPi from the clean side using a ground wire to TP1/2. I assume that means grounding from J5 on the FifoPi . Is that correct?
 
A

A123

Disabled Account
Joined 2020
I'm a noob on this site, so pls take everything with a big grain / pinch of salt...

From my understanding, you ignore the "5V" on the J5 of the StationPi. Instead you follow the User Manual of the FiFoPiQ3 which states:

C. FifoPi Q3 new improvements

* Uses pure 3.3V for a clean side DC power supply. All LDO shave been removed to allow direct operation with a better 3.3V power solution via LifePO4 or ultra capacitor.

J3: Optional RaspberryPi power input

* You can power your RaspberryPi via GPIO through J3, bypassing the Micro-USB connection. To do so, connect a 5V 2A DC power supply to J3, MAINTAINING CORRECT POLARITY!!! We highly recommend you power your RaspberryPI via GPIO through J3 to lower power supply noise on your RaspberryPi. DO NOT connect power to J3 if you already power your RaspberryPi via another method, such as the Micro-USB port.

----

So ignore "5V", instead use 3.3V for J5 on the StationPi.

The "other" 3.3V (J3 on FifoPiQ3) can be ignored because:

DO NOT connect power to J3 if you already power your RaspberryPi via another method, such as the Micro-USB port.
Click to expand...

Other method being already powering a Raspberry Pi on the J3 of the StationPi with 5V.

So nada nothing 3.3V power into both 3.3V inputs on the FiFoPiQ3. It will all be handled externally off the StationPi J5 Audio only power with a single 3.3V feed.

Again, as Ian mentioned this only works for FiFoPi HATs. If you are using a third-party HAT this method won't work...
 
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roderickvd

roderickvd

Member
Joined 2015
I e-mailed Ian and kindly he replied:

You can power FifoPi Pi side from J5 of the StationPi (recommended) or from J3 of the FifoPi. This is correct.

"NO CONNECT FOR FiFoPi" means don't connect if FifoPi is powered from J3.

Please see the schematic for details.
Click to expand...

So I gather:

  1. 5V on StationPi J3 for the RPi, plus:
  2. 5V (preferably clean) on StationPi J5, plus:
  3. 3.3V (clean) on FifoPi J5.

@A123 following the schematic, there is no 3.3V on StationPi J2/J7 pin 1. It's separated from the RPi GPIO header J1.
 
A

A123

Disabled Account
Joined 2020
My goal is to use one MKIII (1 5V, 2 3.3V), so I'm trying to avoid two 5V. I plan to eventually use SuperCaps so I don't want to have to use two MKIII w/ SC for two 5V.

iancanada said:
@ A123
You can use 3.3V rather than the 5V at the audio side if you use a FifoPi.
I built my own DAC with StationPi and LifePO4 MKIII by this way.

Regards,
Ian
Click to expand...

So maybe it's:

  1. 5V on StationPi J3 for the RPi, plus:
  2. 3.3V (clean) on FifoPi J5.
That is maybe all that's needed. If there is no 3.3V option on the StationPi and "NO CONNECT FOR FiFoPi" taken into account, no need to power on the StationPi J5?

Just concerned how the TransportPi will get power if the above works...

"NO CONNECT FOR FiFoPi" means don't connect if FifoPi is powered from J3.
Click to expand...
Is this referring to J3 on the StationPi or J3 on the FiFoPi?

If you are already powering a RPi on J3 off the StationPi, one should not need 5V again off the J3 on the FiFoPi (Powering RPi) or even off the J5 on the StationPi?

It's a bit tricky as two new products are introduced with different power requirements...
 
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A

A123

Disabled Account
Joined 2020
J. How to produce the best sound quality using your FiFoPi

Power your FiFoPi from a directly-connected 3.3V ultra capacitor or LiFePO4 battery supply
The quality of your FiFoPi power supply directly impacts both FiFoPi and clock performance. As an alternative to very good quality power supplies, we have used a directly-connected 3.3V LiFePO4 or Ultra Capacitor supplies. Our experience is that these types of supplies do a very good job of improving the resulting sound quality AND are very hard to better with a traditional power supply. You can connect this type of supply directly to the isolated DC input terminal J5. With a 3.3V DC input on J5, the on-board LDOs are automatically bypassed internally because of the dropout voltage is lower than the minimal dropout voltage (about 0.3V).
Click to expand...
From the manual it looks like 3.3V is enough to power a FiFoPi. 5V for the StationPi J3 to power RPi. 3.3V for the FiFoPiQ3 J5 to power FiFoPiQ3?

TransportPi?
 
K

kirks

Member
Joined 2015
Ian responded to my email regarding StationPi. I think this should answer our questions.

"
1. 5V to StationPi J3 (Yes)

2. 3.3V to StationPi J5 (Yes)

3. 3.3V to FifoPiQ3 J5 (Yes)

4. Ground wire from FffoPiQ3 J5 Gnd to StationPi Gnd (Yes)

If it is possible, please post the answer in the thread to share with more community members."
 
W

wcwc

Member
Joined 2011
^^

That is what I thought. I will try it both ways, but I would prefer to only use only 2 power feeds (5V to both J3 and J5 on StationPi), instead of 3 like you list above. We will see how much of a difference it makes. I am using Salas Ref-D for 3.3V feed and L-adaptor for the 5V feed.
 
A

A123

Disabled Account
Joined 2020
That makes sense. Before the StationPi was conceived, I remembered something like FiFoPiQ3 needs power and clocks need power (2 x 3.3V).

I'm cool with two 3.3V (MKIII). Two 5V would of complicated things.

So you can feed "5V" label on the StationPi J5 3.3V. Nice.

Going to need two UcHybrids tho...

Thanks for posting info.


EDIT: Ian, TransportPi will work with two 3.3V feeds? You mentioned it works with a DAC attached, but I'll be running solely a TransportPi...
 
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A

A123

Disabled Account
Joined 2020
Hi Ian. No need to answer the EDIT: above.

Just read the TransportPi manual regarding 3.3V:

By default, the TransportPi was designed to pick up power from GPIO (usually from FifoPi clean side if it's integrated). FifoPi clean side power supply could be already good enough. But you still have chance to improve more to the power supply of TransportPi, you can do...
Click to expand...
So it seems like it should work powering the FiFoPi fed 3.3V. If not, I will just use the extra 3.3V on the MKIII since there are 6 available total 3.3V.
 
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iancanada

iancanada

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Joined 2009
twitter.com/iancanadaTT
Paid Member
kirks said:
Ian responded to my email regarding StationPi. I think this should answer our questions.

"
1. 5V to StationPi J3 (Yes)

2. 3.3V to StationPi J5 (Yes)

3. 3.3V to FifoPiQ3 J5 (Yes)

4. Ground wire from FffoPiQ3 J5 Gnd to StationPi Gnd (Yes)

If it is possible, please post the answer in the thread to share with more community members."
Click to expand...

Thanks Kirks, that's correct.
I'm tied up with GB2020Q3 orders. I'm so sorry for my late response.

Regards,
Ian
 
iancanada

iancanada

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Joined 2009
twitter.com/iancanadaTT
Paid Member
AirAir said:
In my experience, the greatest effect of grounding is J1 on FifoPi (J3).
Waiting for ReclockPi from Jan. :wiz:
Click to expand...

The ReclockPi prototype is already under testing now. Very promising on both measurement result and real listening test. It could be the best way to upgrade FifoPi after many years of releasing, except XOs them self. I'm trying to make it available as soon as possible. But unfortunately I can not include it this time in the GB2020Q3.

Regards,
Ian
 
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