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[10:48:31] <mark__> To elaborate, the problem I'm trying to solve is that a USB-hub with 4 USB dongles attached to the A10 sometimes causes it to freeze during a boot, supposedly because of the amount of power it requiers.
[10:51:35] <lukas2511> that sounds like it would also cause issues if you enable it later
[10:53:05] <lukas2511> i'd try an externally powered hub or test if adding a capacitor fixes it rather than just trying to "fix" it in software
[10:59:06] <tbr> sounds like I'd power the hub directly and make sure the psu is well spec'd
[11:06:08] <mark__> a powered hub is tricky as the A10 is gonna have to use PoE
[11:06:45] <mark__> adding a capacitor seems like a plan, but how would I go about that without soldering?
[11:08:05] <lukas2511> yea mh that'd be problematic
[11:09:39] <lukas2511> if you want to "fix" it in software you can probably alias the kernel module to "off", and load it manually (or by script) later
[11:11:18] <mark__> Yeah I could try that. I've (re-)attached the hub while the A10 was running a lot of times and this never caused any trouble. I suppose at boot-time it's just too much draw
[11:12:10] <lukas2511> did you do any load tests after plugging everything in?
[11:13:36] <mark__> They're bluetooth dongles, if letting all of them inquire for nearby devices counts as a load-test then yes, I did :)
[11:14:18] <mark__> if you mean load-test on the device as a whole, then probably not..
[11:15:50] <lukas2511> i mean, i don't know what you are going to do with it, but if it gets any load it may require more power again, and may fail in operation
[11:17:48] <lukas2511> i'd recommend to test everything at high load, to see if it fails. also i'd recommend measuring the voltage drop over the ethernet cable
[11:18:16] <mark__> That's true. I did not notice it failing but that doesn't mean it can't happen of course
[11:18:18] <lukas2511> if you are running a 5V A10 board and are running 5V over the ethernet cable it will probably drop way too far
[11:18:43] <mark__> Aha. That's a good one
[11:21:28] <lukas2511> on passive power over ethernet i'd try to run 12-24V over the cable and use a switching power supply to 5V near the board itself
[11:23:09] <mark__> Like this? https://www.olimex.com/Products/Modules/Ethernet/MOD-POE-V2/
[11:24:46] <lukas2511> i think this is for active poe, and it needs a minimum of 36V (usally 48V), i'm not sure if it will work by just giving it power
[11:26:58] <lukas2511> actually i'm not sure what specific product you'd want to use, the only time i build something like this i build the power supply myself
[11:28:47] <lukas2511> if it should be easy i'd just give the a20 micro board a try, and power it with 12V over the ethernet cable. it has the necessary 5V converter on board, and should be able to handle a slight voltage drop on input
[11:30:57] <lukas2511> or buy something like http://www.amazon.de/injector/dp/B001RAZKZC and http://www.amazon.de/splitter/dp/B001PS4NWW which should work as a set
[11:31:53] <mark__> Think the tp-link is laying around somewhere
[11:32:09] <mark__> thought that this was similar to the mod-poe-v2 board though
[11:32:22] <lukas2511> yea the mod-poe-v2 board would be compatible with the injector
[11:33:00] <lukas2511> but there are no power specs on the mod-poe-v2
[11:33:18] <lukas2511> so i can't tell if it would provide enough power to your board
[11:33:25] <lukas2511> the tp-link splitter can handle 2A@5V
[11:34:03] <mark__> My netgear switch says it's outputting 47V to the board.. should be plenty :o
[11:34:24] <lukas2511> what netgear switch do you have?
[11:34:37] <mark__> GS110TP
[11:35:54] <lukas2511> yea that thing does the same as the injector would do, so on that side you're probably fine
[11:37:12] <lukas2511> iirc there is a way to check input voltage in software
[11:37:29] <lukas2511> somewhere around /sys/class/power_supply
[11:37:50] <lukas2511> you should look for that, and see if it drops when you plug in your hub after the board has booted
[11:40:08] <lukas2511> (or if you have a multimeter around just use that)
[11:42:04] <mark__> sys/class/power_supply/ac/voltage_now said 4.98 with hub attached, 5.08 after detaching it. Let's see after a reboot
[11:43:59] <mark__> it does drop from 5.05 to 4.92 but that doesn't seem like a problem
[11:44:20] <lukas2511> input tolerance is 3.8V to 6.3V if i'm looking at the right datasheet, so yea, doesn't seem like a problem
[11:45:02] <lukas2511> so yea, maybe just try aliasing usb stuff to "off", and loading it by script after boot
[11:45:55] <lukas2511> not entirely sure what you need to alias, i'd probably try "alias usb off"
[11:46:31] <lukas2511> there should be a documentation somewhere... ;)
[11:47:19] <mark__> Hehe, yeah I'll go and read up on that myself, you've helped me enough as it is
[11:47:23] <mark__> thanks a lot :)
IRC #olimex 2015-05-11
[10:44:51] <mark__> Hi. Does anyone know a way to delay power-on of the USB controller on an A10 board, perhaps through a kernel/u-boot setting of some sort?[10:48:31] <mark__> To elaborate, the problem I'm trying to solve is that a USB-hub with 4 USB dongles attached to the A10 sometimes causes it to freeze during a boot, supposedly because of the amount of power it requiers.
[10:51:35] <lukas2511> that sounds like it would also cause issues if you enable it later
[10:53:05] <lukas2511> i'd try an externally powered hub or test if adding a capacitor fixes it rather than just trying to "fix" it in software
[10:59:06] <tbr> sounds like I'd power the hub directly and make sure the psu is well spec'd
[11:06:08] <mark__> a powered hub is tricky as the A10 is gonna have to use PoE
[11:06:45] <mark__> adding a capacitor seems like a plan, but how would I go about that without soldering?
[11:08:05] <lukas2511> yea mh that'd be problematic
[11:09:39] <lukas2511> if you want to "fix" it in software you can probably alias the kernel module to "off", and load it manually (or by script) later
[11:11:18] <mark__> Yeah I could try that. I've (re-)attached the hub while the A10 was running a lot of times and this never caused any trouble. I suppose at boot-time it's just too much draw
[11:12:10] <lukas2511> did you do any load tests after plugging everything in?
[11:13:36] <mark__> They're bluetooth dongles, if letting all of them inquire for nearby devices counts as a load-test then yes, I did :)
[11:14:18] <mark__> if you mean load-test on the device as a whole, then probably not..
[11:15:50] <lukas2511> i mean, i don't know what you are going to do with it, but if it gets any load it may require more power again, and may fail in operation
[11:17:48] <lukas2511> i'd recommend to test everything at high load, to see if it fails. also i'd recommend measuring the voltage drop over the ethernet cable
[11:18:16] <mark__> That's true. I did not notice it failing but that doesn't mean it can't happen of course
[11:18:18] <lukas2511> if you are running a 5V A10 board and are running 5V over the ethernet cable it will probably drop way too far
[11:18:43] <mark__> Aha. That's a good one
[11:21:28] <lukas2511> on passive power over ethernet i'd try to run 12-24V over the cable and use a switching power supply to 5V near the board itself
[11:23:09] <mark__> Like this? https://www.olimex.com/Products/Modules/Ethernet/MOD-POE-V2/
[11:24:46] <lukas2511> i think this is for active poe, and it needs a minimum of 36V (usally 48V), i'm not sure if it will work by just giving it power
[11:26:58] <lukas2511> actually i'm not sure what specific product you'd want to use, the only time i build something like this i build the power supply myself
[11:28:47] <lukas2511> if it should be easy i'd just give the a20 micro board a try, and power it with 12V over the ethernet cable. it has the necessary 5V converter on board, and should be able to handle a slight voltage drop on input
[11:30:57] <lukas2511> or buy something like http://www.amazon.de/injector/dp/B001RAZKZC and http://www.amazon.de/splitter/dp/B001PS4NWW which should work as a set
[11:31:53] <mark__> Think the tp-link is laying around somewhere
[11:32:09] <mark__> thought that this was similar to the mod-poe-v2 board though
[11:32:22] <lukas2511> yea the mod-poe-v2 board would be compatible with the injector
[11:33:00] <lukas2511> but there are no power specs on the mod-poe-v2
[11:33:18] <lukas2511> so i can't tell if it would provide enough power to your board
[11:33:25] <lukas2511> the tp-link splitter can handle 2A@5V
[11:34:03] <mark__> My netgear switch says it's outputting 47V to the board.. should be plenty :o
[11:34:24] <lukas2511> what netgear switch do you have?
[11:34:37] <mark__> GS110TP
[11:35:54] <lukas2511> yea that thing does the same as the injector would do, so on that side you're probably fine
[11:37:12] <lukas2511> iirc there is a way to check input voltage in software
[11:37:29] <lukas2511> somewhere around /sys/class/power_supply
[11:37:50] <lukas2511> you should look for that, and see if it drops when you plug in your hub after the board has booted
[11:40:08] <lukas2511> (or if you have a multimeter around just use that)
[11:42:04] <mark__> sys/class/power_supply/ac/voltage_now said 4.98 with hub attached, 5.08 after detaching it. Let's see after a reboot
[11:43:59] <mark__> it does drop from 5.05 to 4.92 but that doesn't seem like a problem
[11:44:20] <lukas2511> input tolerance is 3.8V to 6.3V if i'm looking at the right datasheet, so yea, doesn't seem like a problem
[11:45:02] <lukas2511> so yea, maybe just try aliasing usb stuff to "off", and loading it by script after boot
[11:45:55] <lukas2511> not entirely sure what you need to alias, i'd probably try "alias usb off"
[11:46:31] <lukas2511> there should be a documentation somewhere... ;)
[11:47:19] <mark__> Hehe, yeah I'll go and read up on that myself, you've helped me enough as it is
[11:47:23] <mark__> thanks a lot :)
