The one thing I remember about the BBB is that the processor will be damaged if an I/O pin has a voltage on it without being powered up itself. Perhaps this is what has happened to miero, sad and frustrating, but something to be aware of and it needs to be handled correctly. The last thing anyone needs is a dead piece of equipment because of a blackout or something simple that with some thought could be prevented.
Have a thought regards this, just not the time to type it.
Chuz
Drew.
Have a thought regards this, just not the time to type it.
Chuz
Drew.
This is very right, and Russ have also mentioned earlier. The main processor in BBB (and other devices witch are based on these type processors) it can be damaged if one or many peripheral devices of it, deliver high levels signals to the processor I/O ports, before the processor itself is powered. This is about a "power on" sequence. The designer have to care to manage the power up sequence so, to assure the processor is powered first, then the peripheral system.
When "power down" everything it happen in opposition. If the processor lose its power first, and the peripherals still deliver it signals, it can be damaged. The power down sequence is just as the same important to be managed as the power up.
Maybe Miero have not done right about his device, but similar event it may happen accidentally to everybody. This incident have revealed and put it in discussion that power down sequence in BBB it may have an issue. The protection to event in this area is not as supposing to be, the board it can be damaged, and it seems that there is no control on this so far...
As the BBB is build/designed it looks very plausible that there is no manage of the power down sequence in the system.
I think this simple incident it have revealed an aspect of the BBB functionality, which it request a closer look and attention... If there is an design issue, that have to be addressed by the producer. I think is not any negativity in bringing things to light, or discussing a possible issue. If there is no any issue, and this is confirmed, then is everything all right, and everybody happy...
BTW, it could be both nice and interesting if one of the BBB designers it could assure and maybe demonstrate us by simple means, that in the BBB power management the processor is the last one which lose the power, when one take out the contact from the wall (accidentally or not)... When such incident it happen with your TV, computer, player or what so ever, nothing is damaged, and it start again just fine...
When "power down" everything it happen in opposition. If the processor lose its power first, and the peripherals still deliver it signals, it can be damaged. The power down sequence is just as the same important to be managed as the power up.
Maybe Miero have not done right about his device, but similar event it may happen accidentally to everybody. This incident have revealed and put it in discussion that power down sequence in BBB it may have an issue. The protection to event in this area is not as supposing to be, the board it can be damaged, and it seems that there is no control on this so far...
As the BBB is build/designed it looks very plausible that there is no manage of the power down sequence in the system.
I think this simple incident it have revealed an aspect of the BBB functionality, which it request a closer look and attention... If there is an design issue, that have to be addressed by the producer. I think is not any negativity in bringing things to light, or discussing a possible issue. If there is no any issue, and this is confirmed, then is everything all right, and everybody happy...
BTW, it could be both nice and interesting if one of the BBB designers it could assure and maybe demonstrate us by simple means, that in the BBB power management the processor is the last one which lose the power, when one take out the contact from the wall (accidentally or not)... When such incident it happen with your TV, computer, player or what so ever, nothing is damaged, and it start again just fine...
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Gerald Coley, the designer of BBB HW has written: "After it powers down, then you can remove the power. We need to make sure the PMIC powers down all the rails to the processor in order."
Source: https://groups.google.com/forum/#!category-topic/beagleboard/IVqIw-hCMcA
Which implies that processor power down sequence is not handled on power loss.
Source: https://groups.google.com/forum/#!category-topic/beagleboard/IVqIw-hCMcA
Which implies that processor power down sequence is not handled on power loss.
Ok, as a little thought, don't have my BBB at hand, is there a diode on the input? If so, we monitor the voltage after the diode and feed it into an arduino of sorts. This can have a battery supply or a cap suitable for the voltage required to hold the BBB up for as long as it takes to turn off Botic and then hold the power down input to the BBB for as long as required to shut down correctly? 8 secs was mentioned, haven't fired mine as yet as waiting for Botic to be ready.
Am happy to have a crack at that coding and supply as miero does, have access to a small arduino board that would be suitable, the other thought is, if a Buff was used, not sure how many people use hifiduino but am sure that functionality could also be added there.
Not ideal, but the easiest way I see to ensure it can still be unplugged like an appliance but the BBB can be shut down safely.
That's those 2 cents anyway.
Chuz,
Drew.
Am happy to have a crack at that coding and supply as miero does, have access to a small arduino board that would be suitable, the other thought is, if a Buff was used, not sure how many people use hifiduino but am sure that functionality could also be added there.
Not ideal, but the easiest way I see to ensure it can still be unplugged like an appliance but the BBB can be shut down safely.
That's those 2 cents anyway.
Chuz,
Drew.
Botic already isolates to the BBB outside signals, and ensures proper power up/down sequence. It will not send any signal to any IO when the BBB is powered down.
The problem is with the BBB itself, it could be damaged by a hard shutdown regardless of any outside influence at all. Because internally it must shutdown its own rails in the correct order. If you sat there and just booted and then pulled the power several times you could likely kill one.
Unfortunately that seems to be in my opinion a pretty serious design flaw. I wish they would address it, because hard power downs are a reality (power failure) that every designer should be prepared for,
The problem is with the BBB itself, it could be damaged by a hard shutdown regardless of any outside influence at all. Because internally it must shutdown its own rails in the correct order. If you sat there and just booted and then pulled the power several times you could likely kill one.
Unfortunately that seems to be in my opinion a pretty serious design flaw. I wish they would address it, because hard power downs are a reality (power failure) that every designer should be prepared for,
Agreed Russ,
Quite ridiculous.
Ok, so for us, Botic is ok for a hard shutdown, so we really only need an external source of power for the BBB and a way to tell it to shut down, which pin is it using to start the shutdown sequence? How long does it need to be held for to shut down?
At least you doing the Botic were already aware and have obviously taken steps to avoid this Russ, much appreciated.
Have you any thoughts on another way? Almost thinking the external supply could simply drive a couple relays, one powers the BBB and another drops out and closes the shut down input to begin the shutdown sequence. By this time the Botic has already shutoff so no further voltage on any pins from there. This should not be a major drama I think, really quite simple and should be easy to duplicate, perhaps an add on board for you Russ with a couple of relays and possibly a cap for folks to solder on? Can do a couple experiments to see where it sits, can someone advise what current it uses as a shutdown sequence?
Chuz,
Drew.
Quite ridiculous.
Ok, so for us, Botic is ok for a hard shutdown, so we really only need an external source of power for the BBB and a way to tell it to shut down, which pin is it using to start the shutdown sequence? How long does it need to be held for to shut down?
At least you doing the Botic were already aware and have obviously taken steps to avoid this Russ, much appreciated.
Have you any thoughts on another way? Almost thinking the external supply could simply drive a couple relays, one powers the BBB and another drops out and closes the shut down input to begin the shutdown sequence. By this time the Botic has already shutoff so no further voltage on any pins from there. This should not be a major drama I think, really quite simple and should be easy to duplicate, perhaps an add on board for you Russ with a couple of relays and possibly a cap for folks to solder on? Can do a couple experiments to see where it sits, can someone advise what current it uses as a shutdown sequence?
Chuz,
Drew.
I don't have my BBB yet so the answers to this may already catered for and I may just be highlighting a hole in my understanding but leave aside the poor design highlighted above and pretend that power outages never happen(!); we still have everyday use to consider.
We will need to initiate a a clean shutdown at, say, the end of a listening session without having to do things like remote management of the BBB, otherwise it won't be an appliance. I'm assuming the BBB will be embedded inside the DAC enclosure and be headless.
Ray
Postscript: whoops, didn't see PET-240's post in time....
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Non implementing a effective power down sequence on power failure scenario it have of course something to do with a lower (production/design) cost.
As I have pointed earlier, a elegant and very professional protection on power failure is to monitor the AC of the PSU, and give it to the processor the information about power failure/lose. This information will trigger a safe shoutdown sequence as that coming from the Power Off button. A small backup in the PSU will cover the time needed for the safe shutdown.
As I can not trust very much that a such BBB design issue it will be addressed in the near future, here is my proposal:
One of the available I/O ports of the processor can do the job as monitoring pulses obtained from an AC signal coming from outside. There is not very difficult to realize a simple hardware to do this task. A small piece of software running in real time will care about the AC signal. Missing pulses of this signal it may trigger a power failure routine (just start the soft shutdown sequence).
The user should care to provide an AC signal to the board, and will also care for a backup in his own PSU.
I think all this it may not be very difficult to be realized from user side, if that user knows enough details to implement a such mechanism. Maybe in a small corner of the Botic board... Or just a small PCB to be attached to one or another header of the BBB board...
As I have pointed earlier, a elegant and very professional protection on power failure is to monitor the AC of the PSU, and give it to the processor the information about power failure/lose. This information will trigger a safe shoutdown sequence as that coming from the Power Off button. A small backup in the PSU will cover the time needed for the safe shutdown.
As I can not trust very much that a such BBB design issue it will be addressed in the near future, here is my proposal:
One of the available I/O ports of the processor can do the job as monitoring pulses obtained from an AC signal coming from outside. There is not very difficult to realize a simple hardware to do this task. A small piece of software running in real time will care about the AC signal. Missing pulses of this signal it may trigger a power failure routine (just start the soft shutdown sequence).
The user should care to provide an AC signal to the board, and will also care for a backup in his own PSU.
I think all this it may not be very difficult to be realized from user side, if that user knows enough details to implement a such mechanism. Maybe in a small corner of the Botic board... Or just a small PCB to be attached to one or another header of the BBB board...
It looks like adding a battery it will be the less expensive solution... At least BBB it is designed to run on battery, and this it have the advantage of a minimal noise in the system. One may choose to power the whole system as usually from battery, and recharge it when/while the system is off. It may be a quite good and cheap solution...
Then one have to pay attention to not disconnect the battery accidentally...
Then one have to pay attention to not disconnect the battery accidentally...
It's a valid point. I have powered mine down hard at least 20 times and not had any failure. Still this is something they could easily fix, and I don't imagine it need cost any more (or very very little) in terms of manufacturing though it would certainly take some additional design effort. The BBB is well designed in many other respects, so I am a bit surprised.
I agree. Its more that, with the BBB, we have what we have and I am not sure of the value in seeking an external solution.
I can agree to an extend with treating the BBB almost as a disposable/consumable component; fortunately where I live power failures are rare and I don't see the need to engineer a complex solution to deal with them, nothing more complex than the option of a plug in battery should suffice for those that want/need the insurance. It's worth considering the consequences of treating a component as disposable when, at least currently, demand for that component outstrips supply.
What I do think needs to be addressed is the issue of not inviting failures just through everyday use, turning the thing on and off. I think Russ has power up sequencing under control but power down needs to have some certainty as well as I imagine most Botic users will have the BBB headless and buried inside their DAC enclosure without an easy means of remotely controlling it. Perhaps a simple approach would be to leave the BBB permanently powered up by connecting it's power supply to a point before the DAC on/off switch, thus removing the need for controlled shutdowns in everyday use but with a discrete 'reset' type button that will trigger a shutdown on the occasions when power does need to be removed? For those who don't want to leave it permanently on some ritual around a multiple step power up/down would take care of things - that's what I think I would like to do;
Power up Step 1: turn on IEC connector switch to power up BBB.
Power up Step 2: turn on DAC via front panel switch everything else powers up with correct sequencing via Botic.
Enjoy Music
Power Down Step 1: turn off DAC via front panel switch to power sequence down everything except the BBB.
Power Down Step 2: press 'reset' button to shutdown BBB.
Power Down Step 3: turn off at IEC connector switch to remove all power.
Ray
What I do think needs to be addressed is the issue of not inviting failures just through everyday use, turning the thing on and off. I think Russ has power up sequencing under control but power down needs to have some certainty as well as I imagine most Botic users will have the BBB headless and buried inside their DAC enclosure without an easy means of remotely controlling it. Perhaps a simple approach would be to leave the BBB permanently powered up by connecting it's power supply to a point before the DAC on/off switch, thus removing the need for controlled shutdowns in everyday use but with a discrete 'reset' type button that will trigger a shutdown on the occasions when power does need to be removed? For those who don't want to leave it permanently on some ritual around a multiple step power up/down would take care of things - that's what I think I would like to do;
Power up Step 1: turn on IEC connector switch to power up BBB.
Power up Step 2: turn on DAC via front panel switch everything else powers up with correct sequencing via Botic.
Enjoy Music
Power Down Step 1: turn off DAC via front panel switch to power sequence down everything except the BBB.
Power Down Step 2: press 'reset' button to shutdown BBB.
Power Down Step 3: turn off at IEC connector switch to remove all power.
Ray
Power sequencing - both up and down will be handled absolutely correctly by the Botic.
That's actually a very simple thing to do. There is nothing lacking in that regard - power up and power down will ensure that there is no I/O driven when the BBB is not in a "power good" state.
It's up to BBB designers to fix their product, but I do think having a battery attached is definitely viable fail safe - if you are always around while it's on. Generally speaking its not a great idea to do a hard power down on Linux anyway - but this depends on the kernel and filesystems chosen. Still - the hardware itself should not fail....
That's actually a very simple thing to do. There is nothing lacking in that regard - power up and power down will ensure that there is no I/O driven when the BBB is not in a "power good" state.
It's up to BBB designers to fix their product, but I do think having a battery attached is definitely viable fail safe - if you are always around while it's on. Generally speaking its not a great idea to do a hard power down on Linux anyway - but this depends on the kernel and filesystems chosen. Still - the hardware itself should not fail....
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The router distributions - for example, OpenWRT - handle power failures without issues.
But they typically use more restrictive filesystem layouts than a server or desktop Linux distribution.
The RaspberryPI must not have this hardware weakness, lots of them would have failed by now if it did (given their target market)?
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Power sequencing - both up and down will be handled absolutely correctly by the Botic.
That's actually a very simple thing to do. There is nothing lacking in that regard - power up and power down will ensure that there is no I/O driven when the BBB is not in a "power good" state.
It's up to BBB designers to fix their product, but I do think having a battery attached is definitely viable fail safe - if you are always around while it's on. Generally speaking its not a great idea to do a hard power down on Linux anyway - but this depends on the kernel and filesystems chosen. Still - the hardware itself should not fail....
Thanks Russ, and apologies if I misunderstood what you have said previously.
My new Buffalo 3 DAC and BBB should be with me fairly soon now so things are beginning to come together.
Ray
Just remember, you need to play 48kHz/96kHz/192kHz material or do the external resampling first to these frequencies. Otherwise you'll be listening to artifacts from fast but low-quality conversion algorithms.
The BBB is just too slow for play 44.1kHz well without an audio cape.
I hope the cape will be available soon...
The BBB is just too slow for play 44.1kHz well without an audio cape.
I hope the cape will be available soon...
USB is viable alternative for all sample rates
Don't forget that the BBB handles 44.1 material fine through USB. That is how I am using mine until the Botic is complete. Sounds amazing(ly better than usb from my PC), and everything in native resolution.
Don't forget that the BBB handles 44.1 material fine through USB. That is how I am using mine until the Botic is complete. Sounds amazing(ly better than usb from my PC), and everything in native resolution.