Battery Pack + Alfa AWUS036H = No boot! (problem solved)


18 posts
by TCB13 » Sat Sep 08, 2012 7:40 pm
Hello,
I've managed to configure and install my stuff into a raspberry pi and everything works fine while connected to a power supply, however in a USB battery pack the situation is different.

I've the following:


As you can see on the link the Anker Astro have 2 USB ports, I'm connecting the Raspberry Pi on the first one and the USB Hub power cable on the second one.

If I start the device with the USB Hub connected it won't boot, the LEDs are all turned ON but nothing happens at all.
If remove everything and just leave the Raspberry Pi connected to the battery pack it boots up fine.

Any tips? Thank you.
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by mahjongg » Sat Sep 08, 2012 10:57 pm
measure the voltage between TP1 and TP2 on the PI, with and without the hub attached, publish the results here.

A couple of questions:
How are the hub and the PI interconnected (except obviously that they share their GND signals, and are powered essentially from the same source, but how does the data connection work, does it also cause another GND and power connection)?
Do you have a rev2 board or did you bypass the USB polyfuses F1 & F2?
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by Genius23008 » Sun Sep 09, 2012 6:01 am
The battery pack probably only just powered the pi anyway. You can get the Pi and a hub going, that's my setup. I'm using a £10 chinese battery which outputs 1a in one port and 2a in the other - it's perfect!
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by TCB13 » Sun Sep 09, 2012 12:57 pm
mahjongg wrote:measure the voltage between TP1 and TP2 on the PI, with and without the hub attached, publish the results here.

A couple of questions:
How are the hub and the PI interconnected (except obviously that they share their GND signals, and are powered essentially from the same source, but how does the data connection work, does it also cause another GND and power connection)?
Do you have a rev2 board or did you bypass the USB polyfuses F1 & F2?


My board is not rev2 and I didn't touch the hardware (yet). Isn't the polyfuses bypass only needed to ensure I can get more power from the USB ports? Anyway, since my hub seems to be sending power back over the USB port connected to the Pi is it possible to power it up just on that port? (need to bypass polyfuses right?)

Pi booted up without any hub or USB device just power from the battery pack:
TP1-TP2: 4.71V
Image

Pi with all the USB devices hanged up:
TP1-TP2: 4.78V ==> Is my hub sending power back...
Image

I've also notice if I disconnect the main power of the Pi and leave the powered Hub connected to the battery pack the Pi LEDs are still turned on but it doest not work. :?:

Thank you.
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by mahjongg » Sun Sep 09, 2012 1:25 pm
In the full configuration you do seem to simultaneously be front feeding the PI, and back feeding it through the connection to the hub, at least that is what is what is happening if you remove the min USB front feed connection and the LED on the PI keeps burning. The PI gets some power from the backfeed, but due to the polyfuses, its much less than it needs to operate (on a rev2 PI these fuses are removed, and backfeeding would work, so you no longer would need front feeding through the mini USB.
Unfortunately I have no idea why the PI doesn't work in this configuration, all I can say it doesn't seem to be a power issue. 4.78V seems enough for the PI itself, and all USB peripherals get power directly not through the PI (through the PI's polyfuses) so they also should get enough.

And yes, bypassing the USB polyfuses is just to get more power to the USB device connected to the PI, that, and it allows the PI to be backfed correctly.
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by TCB13 » Sun Sep 09, 2012 1:39 pm
mahjongg wrote:(on a rev2 PI these fuses are removed, and backfeeding would work, so you no longer would need front feeding through the mini USB.
Unfortunately I have no idea why the PI doesn't work in this configuration, all I can say it doesn't seem to be a power issue.
And yes, bypassing the USB polyfuses is just to get more power to the USB device connected to the PI, that, and it allows the PI to be backfed correctly.


So... do you recommend me to just bypass the fuses? I can try to see if the Pi can work fine with only with the back feed.

Anyway... I'm disappointed one more time with chineses, they should at least thing about including a diode in the Hub, this back feed doesn't seem to be a good thing. :evil:
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by TCB13 » Sun Sep 09, 2012 2:44 pm
Good news,
I managed to bypass the polyfuses and now I've got the Pi full powered from the Hub back feed. TP1-TP2 voltage seems to be good. (4.6v).

Bad news,
If I try to boot up this thing with the Alfa card connected the OK LED stops bilking after 10 seconds and nothing else happens. The network LEDs are ON.

Is there a way I can try to debug what's stopping the boot process?

Image
(Open in new window if you want to see my poor soldering skills in action!)

Thank you.
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by TCB13 » Sun Sep 09, 2012 5:14 pm
After reading a lot of bugs and trying out some stuff I discovered that my boot issue is not related to the HUB itself.

The issue is caused booting the device with the Alfa AWUS036NHA card attached to it. I tried to boot the Pi with other wireless card attached an Alfa AWUS036H and it boots up correctly and this second card is much more power hungry.

I would like to know if anyone has experience the same behaviors and if there are fixes... If someone that are better with electronics than me can discover and document what is going is related card I can email Alfa Network and ask them to fix their hardware. My company works with them almost everyday. :geek:

Thank you.

Note to admin: Please change the tittle of this thread to "Alfa AWUS036NHA is killing the boot." or something more convenient.
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by conundrum » Sat Sep 15, 2012 11:36 am
Hi,
It might be worth adding a simple sensor which only turns the conflicting device on once the OK light starts blinking.
A simple CdS, photodiode or infrared LED in reverse connected to the base and emitter on a high gain PNP transistor with a parallel capacitor so that it only stays on while the LED is blinking would work.
With LEDs you need a RX wavelength longer than the TX so for green LEDs an infrared LED would work.

Hope this helps..
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by TCB13 » Sat Sep 15, 2012 11:41 am
Thats... kinda overkill but thank you for the suggestion! :mrgreen:
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by obcd » Sat Sep 15, 2012 11:53 am
Does it work if you plug the Alpha in after the Pi has booted?
4.65V is on the low site. 4.85V-5.25V is recommended for stable operation.
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by TCB13 » Sat Sep 15, 2012 12:02 pm
obcd wrote:Does it work if you plug the Alpha in after the Pi has booted?
4.65V is on the low site. 4.85V-5.25V is recommended for stable operation.


Yes everything works fine if I connected the Alfa after the boot.
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by obcd » Sat Sep 15, 2012 12:56 pm
I really am suspecting your power supply voltage.
The Alpha is probably creating a small voltage dip when it turns on, and that might kill the Pi.
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by TCB13 » Sat Sep 15, 2012 1:30 pm
obcd wrote:I really am suspecting your power supply voltage.
The Alpha is probably creating a small voltage dip when it turns on, and that might kill the Pi.


I tried to measure it with my crappy multimeter and I didn't notice anything... probably if there is a real dip is to short for my equipment...
But... that dip is only screwing the Pi at the boot time...
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by MmmPi » Sat Sep 15, 2012 2:28 pm
Eliminate the power supply as a possible problem to narrow down the issue.
Hack up a usb cable to feed the Alfa power from a separate source. If you have a Y usb cable (extra plug for limited power ports) just tape over the the power pins on the data plug.
Try adding a capacitor if its a power dip.
The Pi may just be more vulnerable to dips during boot.
~Edit~ Oh, hey, your hub has a Y cable. :lol: Yea, try a little tape & power it from a separate source.

A little unclear if you tried booting the Pi w/ AWUS036NHA from a normal power supply (non-battery). Original post says AWUS036H but picture in your next post shows AWUS036NHA
In case anyone isn't aware: Don't order from RS / Allied if you can avoid it. Unless you like frustration that is
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by TCB13 » Sat Oct 27, 2012 11:43 pm
Ok, so I know this a little old but I've been out for some time.

After some soldering and making myself hacked USB cables to power the devices directly com the same source of the Pi, I found out that the problem was indeed related to power.
Apparently the crappy Chinese USB adapters I got couldn't handle the powered I needed. So, for everyone, just don't buy ones similar to the picture:
Image
It took me a long to find this ones with cable, specially here in Europe but they suck.
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by itimpi » Sun Oct 28, 2012 5:37 am
When there is talk of powered USB hubs we mean powered by a separate power adaptor. That picture shows a hub that takes its power from the USB - something that the RPi will not support.
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by TCB13 » Sun Oct 28, 2012 11:07 am
Hey? I wes actually supplying the power over the red cable directly on a 2A USB power supply and feeding the pi on back feed using the black cable.
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