Attention to BBB owners!
Be sure that you are powering down your BBB correctly. I've damaged my board by unplugging it from the power adapter. I've done this several times without any problem, but the last one was fatal.
There are several ways how to power down BBB correctly:
- with Linux booted it should be enough to pres power off button once and wait a while
- pressing power off button for 8 seconds until LED turns off
- issuing shutdown command from Linux
Source: BBB_SRM.pdf and my question on https://groups.google.com/forum/#!category-topic/beagleboard/IVqIw-hCMcA
So I think we need also some smart module that will let BBB power down before disconnecting the power from the DAC.
Be sure that you are powering down your BBB correctly. I've damaged my board by unplugging it from the power adapter. I've done this several times without any problem, but the last one was fatal.
There are several ways how to power down BBB correctly:
- with Linux booted it should be enough to pres power off button once and wait a while
- pressing power off button for 8 seconds until LED turns off
- issuing shutdown command from Linux
Source: BBB_SRM.pdf and my question on https://groups.google.com/forum/#!category-topic/beagleboard/IVqIw-hCMcA
So I think we need also some smart module that will let BBB power down before disconnecting the power from the DAC.
Detect in the system software that the power plug is in its place. The most power connectors out there provide a switch which can be use it to get the information about the power plug in place. The absence of this information it may force a shut down sequence. As the BBB do not need high current to function, an enough large capacity in between the PSU and the processor it will give it the time to run the power down/shut down sequence.
So, an even accidental disconnecting of the power plug it may minimise the damages for the system...
Such protection it should be a part of the BBB design itself... But if it will be in place, then it may decrease the sales rates...
So, an even accidental disconnecting of the power plug it may minimise the damages for the system...
Such protection it should be a part of the BBB design itself... But if it will be in place, then it may decrease the sales rates...
I think it may be an design issue of BBB system when it get destroyed by loosing power accidentally. This it may for sure not happen, and it is not happen with the most kind of digital systems, when some minimal protection measures are provided by design.
In the incident described, it seems to me that the processor have lost the power before some peripheral devices, which it were further on, delivering signals to a non powered processor. Maybe the designers of BBB should have a closer look at the problem. If there is an issue with BBB system, then is not very much one can do from outside (user side).
A basic protection system used on quite large scale in such devices, consist of a circuit which count the periods of AC used to feed the power system. When missing pulses (20ms for 50Hz line) are detected a power failure signal it is send out to the system, and it interrupt all ongoing processing. Then is started the shut down routines. The (dedicated) power system is designed to cover the time the system need to run its emergency shut down processes. So, nothing wrong when the main power disappear suddenly, as one take the contact out of the outlet...
It is enough clear that is missing a such elementary protection from the BBB design, for sure to lower the costs...
Else when the BBB board is meant to be powered from a usually AC-DC converter connected into the wall, there is quite difficult to implement a protection as described above... If the relative cheap board get destroyed, then one may buy another one, and so on... The commercial advantages are enough obvious...
A solution to this issue it may be (from the user side) to prevent to take out the the DC plug from the board, but the AC-DC converter itself from the wall. But I`m not very sure if it helps, when the system do not knows when the power is (or it will be) lost...
In the incident described, it seems to me that the processor have lost the power before some peripheral devices, which it were further on, delivering signals to a non powered processor. Maybe the designers of BBB should have a closer look at the problem. If there is an issue with BBB system, then is not very much one can do from outside (user side).
A basic protection system used on quite large scale in such devices, consist of a circuit which count the periods of AC used to feed the power system. When missing pulses (20ms for 50Hz line) are detected a power failure signal it is send out to the system, and it interrupt all ongoing processing. Then is started the shut down routines. The (dedicated) power system is designed to cover the time the system need to run its emergency shut down processes. So, nothing wrong when the main power disappear suddenly, as one take the contact out of the outlet...
It is enough clear that is missing a such elementary protection from the BBB design, for sure to lower the costs...
Else when the BBB board is meant to be powered from a usually AC-DC converter connected into the wall, there is quite difficult to implement a protection as described above... If the relative cheap board get destroyed, then one may buy another one, and so on... The commercial advantages are enough obvious...
A solution to this issue it may be (from the user side) to prevent to take out the the DC plug from the board, but the AC-DC converter itself from the wall. But I`m not very sure if it helps, when the system do not knows when the power is (or it will be) lost...
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Another 6 EUR solution might be adding a rechargeable battery:
BeagleBone Black: BBB - Rechargeable on-board b... | element14
BeagleBone Black: BBB - Rechargeable on-board b... | element14
There may be some alternatives for a power buffer/backup to cover the shutdown sequence. I mention already the use of a (large) capacity in this respect. But the buffer itself is not the main solution.
The most important is in this case is the information about a power failure. This information it have to be detected, and used further to control the safe shutdown process.
There is quite obvious that a power sequence issue of the BBB system it will be enough difficult to be addressed by users of the board. It have to be fixed by the BBB designers...
It is used a power management chip in BBB system. If incidents as recently reported occur, it looks like the information about power failure it still be not used, or is ignored in the shutdown sequence on BBB design.
There is not only the "power up" which is important and needs a carefully management, but the "power down" too. What is happen in "power up" is just reversed in "power down". Both sequences it have to be treated with the same "respect"... to have a fail safe system.
The most important is in this case is the information about a power failure. This information it have to be detected, and used further to control the safe shutdown process.
There is quite obvious that a power sequence issue of the BBB system it will be enough difficult to be addressed by users of the board. It have to be fixed by the BBB designers...
It is used a power management chip in BBB system. If incidents as recently reported occur, it looks like the information about power failure it still be not used, or is ignored in the shutdown sequence on BBB design.
There is not only the "power up" which is important and needs a carefully management, but the "power down" too. What is happen in "power up" is just reversed in "power down". Both sequences it have to be treated with the same "respect"... to have a fail safe system.
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