patniemeyer
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Anyone have wifi dongle without external power?

Sun Jul 15, 2012 8:15 pm

I've been reading posts linked from the wiki regarding which wifi dongles work with which setups and in some cases they explicitly mention that they are referring to using an external hub. What I'm having trouble identifying is someone discussing / confirming a case of getting a dongle working *without* external power...

I'm willing to do the experimentation myself but just thought it would be nice to see what others have / have not gotten working so far.

thanks,
Pat

PaulCheffus
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Re: Anyone have wifi dongle without external power?

Sun Jul 15, 2012 8:45 pm

patniemeyer wrote:I've been reading posts linked from the wiki regarding which wifi dongles work with which setups and in some cases they explicitly mention that they are referring to using an external hub. What I'm having trouble identifying is someone discussing / confirming a case of getting a dongle working *without* external power...

I'm willing to do the experimentation myself but just thought it would be nice to see what others have / have not gotten working so far.

thanks,
Pat
Hi

I have an Edimax EW7811UN wireless dongle running on the Pi without an external hub.

Someone else mentioned this one as also working without a hub
http://www.amazon.co.uk/gp/product/B003 ... d_i=468294

Cheers

Paul
Procrastination - The Thief of Time.

Mikeyl
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Re: Anyone have wifi dongle without external power?

Sun Jul 15, 2012 8:50 pm

I have the same dongle running as well. What made a difference was using a decent power supply - I have an iPad one- with a decent lead. I found that my Kindle lead didn't work properly. I also have a USB webcam working along with the wifi. As a first step to using the Pi on a robot.

Mike

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joan
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Re: Anyone have wifi dongle without external power?

Sun Jul 15, 2012 8:55 pm

I'm using a wifi dongle marketed as sweex. It uses a Ralink chipset and declares itself as idVendor=148f, idProduct=2573.

Plugged directly into the Raspberry. No hub required.

Lorian
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Re: Anyone have wifi dongle without external power?

Sun Jul 15, 2012 9:15 pm

I too have a Edimax EW7811UN and it works without a hub with 3 different PSUs powering the Pi, with no problems.

ejsolutions
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Re: Anyone have wifi dongle without external power?

Sun Jul 15, 2012 10:24 pm

I'm using a cheap "Digitazz" (Ralink RT 5370) one purchased from feeBay, plugged into the top port. Uses RT2800usb driver in Raspbian.

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jbeale
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Re: Anyone have wifi dongle without external power?

Mon Jul 16, 2012 5:41 am

I'm using this tiny WiFi adapter, currently sold at USD 6.12
http://www.ebay.com/itm/330646461862?ss ... 1439.l2649

It is a Realtek RTL8188CU (802.11n). USB VID 0x0BDA, PID 0x8176
So far I've only used in on Windows XP, but I measured a current draw of 92 mA peak, and it works at a 4.5 V supply, so I think it will work fine in the R-Pi without a hub.

Due to the tiny form factor, the built-in antenna is not as good as one with an external antenna, so your WiFi range may suffer. Directly in my laptop I get -64 dB RSSI ("very good" signal strength, 43.5 Mbps) from my router, and I see 11 other networks from surrounding apartments. But using a 6 foot USB extension cord to put it 4 feet up on the wall, I got a -45 dB RSSI ("excellent", 75 Mbps) reading from inSSIDer and I also picked up 20 other networks, which is just as good as a larger USB-WiFi dongle with an external antenna. Pingtest.net says 13 msec ping, 3 msec jitter which is just as good as any other WiFi I've tried. Actual bandwidth to my ISP is 12Mbps up, 0.9 Mbps down, which is all my DSL line ever does.

It gets warm to the touch when operating, but not hot. Well, that depends on the connector it's plugged in to. Being so tiny, nearly all the heat dissipation is through the connector.

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jbeale
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Re: Anyone have wifi dongle without external power?

Mon Jul 16, 2012 6:26 am

Following up my previous post, 'iperf' reports 25 Mbits/sec over the WiFi link to another local WinXP box, so that's the real effective data rate. Not sure why it's so much lower than the 72.0 Mbps link speed that the windows network connection status info box claims. My 100M wired ethernet reports 89.5 Mbps.

(wireless)
iperf -c 192.168.10.103
------------------------------------------------------------
Client connecting to 192.168.10.103, TCP port 5001
TCP window size: 63.0 KByte (default)
------------------------------------------------------------
[1900] local 192.168.10.107 port 1973 connected with 192.168.10.103 port 5001
[ ID] Interval Transfer Bandwidth
[1900] 0.0-10.0 sec 29.9 MBytes 25.0 Mbits/sec
-------------------------------------------------------------------------
(100M wired)
iperf -c 192.168.10.103
------------------------------------------------------------
Client connecting to 192.168.10.103, TCP port 5001
TCP window size: 63.0 KByte (default)
------------------------------------------------------------
[1900] local 192.168.10.100 port 2017 connected with 192.168.10.103 port 5001
[ ID] Interval Transfer Bandwidth
[1900] 0.0-10.0 sec 107 MBytes 89.5 Mbits/sec

CCitizenTO
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Re: Anyone have wifi dongle without external power?

Mon Jul 16, 2012 2:09 pm

You're probably getting lower bandwidth with the wireless for two reasons

1) Interference from 30+ other wireless networks
2) Overhead built into the Ethernet protocol.

Even when I do iperf through my Pi on it's native 100Mbps wired ethernet interface to my desktop computer with only a router between. I get a consistent rate of about 74-75Mbps. I think anywhere from 10-25% overhead is typical. Remember they dont include the overhead when they determine the theoretical maximum speeds so the speeds will always be a bit slower than advertised but they're all doing the same thing so looking at something going 150Mbps on the box vs something that says 100Mbps on the box you would expect the other one to be faster.

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jbeale
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WiFi current draw vs link speed

Tue Jul 17, 2012 6:01 am

Just compared two small USB-WiFi N adapters from ebay. Both devices connected easily from my WinXP laptop to my Linksys WRT160Nv2 router, reporting excellent signal and 72 Mbps link speed. It is interesting to see that both devices keep under the 100 mA limit while working the internet at my DSL speed. But going to a machine on the LAN, the speed goes up and the current draw goes up with it, above 150 mA which is more than the unmodified RPi USB port can reliably provide. So I'd expect either of these devices would be perfectly reliable for internet browsing used direct in the RPi without a supply, but UNreliable for heavy LAN use (eg. high-bitrate video streaming). ...Unless you have faster internet than I do, in which case, web use might hit overcurrent also.

By the way, the RTL8188CU device worked fine at the end of a six foot USB extension cable. The RT5370 device was not reliable on that cable, although it was fine with a 1-foot extender cable.
---
http://www.ebay.com/itm/260976202890
Ralink RT5370 USB-WiFi N adapter (small external 2 dBi antenna)
standby: 66 mA
DSL provider speed test, transmitting: 75 mA (max) 12 Mbps
DSL provider speed test, receiving: 82 mA (max) 0.91 Mbps
iperf speed test to local WinXP box: 173 mA (max) 34.3 Mbps
---
http://www.ebay.com/itm/330646461862
Realtek RTL8188CU USB-WiFi N adapter (internal antenna) (before wrongly listed as 'Ralink')
standby: 84 mA
DSL provider speed test, transmitting: 96 mA (max) 11 Mbps
DSL provider speed test, receiving: 94 mA (max) 0.91 Mbps
iperf speed test to local WinXP box: 157 mA (max) 18.7 Mbps
---
I compared the RT5370 with the included 4-inch long 2 dBi antenna and also a (claimed) 8 dBi TP-Link antenna about 11 inches long. I did not see much difference in the RSSI figures from inSSIDer. A directional antenna works better in open space than indoors with confused beam patterns from all the reflections.

Last item, the first RT5370 I got stopped working after a few days (the ebay guy sent a replacement; thanks!) so I took it apart to have a look, if you're interested:
https://picasaweb.google.com/lh/photo/_ ... directlink
https://picasaweb.google.com/lh/photo/_ ... directlink
Last edited by jbeale on Mon Apr 15, 2013 10:08 pm, edited 1 time in total.

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jbeale
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Re: Anyone have wifi dongle without external power?

Tue Jul 17, 2012 10:37 pm

correction to above post: second device is actually "Realtek" brand, not Ralink.

Realtek RTL8188CU USB-WiFi N adapter (internal antenna)

dirtyburger
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Re: Anyone have wifi dongle without external power?

Tue Jul 17, 2012 10:41 pm

Just about to give this a go on new raspbian image, will let you know how it goes, have found most powered hubs to cause issues to date, but I think I am just unlucky with my hubs that are lying around..... :roll:

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jbeale
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Re: Anyone have wifi dongle without external power?

Wed Jul 18, 2012 1:26 am

This hacked extender cable can make any hub a powered hub, and the +5V to USB-Host and USB-Device is separate so there's no back-feeding of power into the RPi. You can also insert a meter to measure current draw, measure voltage from the host, etc. I'm currently using it with my RPi and a separate +5V supply going to an otherwise-unpowered 4-port hub.
USB-cable-hack.jpg
USB-cable-hack.jpg (56.14 KiB) Viewed 21880 times
better resolution photo: https://picasaweb.google.com/lh/photo/y ... directlink

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mahjongg
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Re: Anyone have wifi dongle without external power?

Wed Jul 18, 2012 1:57 am

What Jbale said is critical, for any USB device on an R-Pi to work two factors must be met, firstly the current consumption of the USB device must be low, at least less than 100 mA, and the second factor is that the device should work with a much lower voltage than is normal for "5 Volt logic", that is much less than the normal 4.75 Volt "5 Volt logic" normally works with.
In practice this means (for the second factor to be true) that we are talking about a "low power USB device" That is a device that uses less than "one USB current unit", with "current unit" meaning 100mA. So the device should use (a lot) less than 100mA, to be able in the calss of devices that will generally work with a lower voltage.
Most USB mice and keyboards are indeed such devices, normally use something like 50mA, and can work with 4.4Volt.

Why is this important? Answer, only because of the polyfuses used in the PI, which are rated 140mA, and have such a high resistance to current that they "steal" output voltage from the USB device (it "Ohm's law")
In fact if the device would use 100mA, then after the fuse, the 5V from the PSU would have dropped to 4.4 Volt! If the current is more than 100mA, there are two problems:
1) The voltage drop will be more severe, so the remaining voltage will be even less than 4.4 Volt, and
2) devices consuming more than 4.4 V are probably not designed as "low power devices", and are less likely to work with just 4.4 Volt.

So for any WiFi adapter to work it must:
use a bit less than 100mA, say just 80mA
and
Can work with just 4.4 Volt

Clearly some WiFi adapters are capable of this, and almost all bluetooth adapters (for wireless keyboards and mice) will use much less current (like 20mA) and should work with 4.4V.
But exceptions may always occur.
On top of that not all WiFi adapters have Linux support, and some have Linux drivers, but these are "closed source" so there is no way to compile them for an the ARM CPU of the R-Pi.
So any widi dongel that will work has to

dirtyburger
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Re: Anyone have wifi dongle without external power?

Wed Jul 18, 2012 2:15 am

I have the Edimax Wifi Dongle working and a Riimote Wireless keyboard/mouse combo, no issues so far, this is on the latest Raspbian image. No hub involved. Using a Samsung mobile charger to power the Pi. For what its worth :D

CCitizenTO
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Re: Anyone have wifi dongle without external power?

Wed Jul 18, 2012 9:14 am

Interesting...

You know doing the math even a Class 1 Bluetooth device would only use 20mA.

It may be that Raspberry Pi's working together may work best utilizing bluetooth connections rather than conventional wifi like Wireless N... Though a quick glance at the net seems to indicate Bluetooth is about 2.1Mbps which isnt horrible if you arent in a rush or working with huge files (2Mbps is about 15MB/min). Might be good for running an IRC server or a forum (that isnt crazy popular like this one)

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mahjongg
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Re: Anyone have wifi dongle without external power?

Thu Jul 19, 2012 1:23 am

from a power consumption POV bluetooth is great, the only problem that its range is measured in centimeters, instead of meters.
A similar technology called zigbee can do hundreds of meters, but at very low speed.
Most WiFi systems won't use 100mA (that is 450mW) so will work fine on the limted power USB ports of the PI.
Bluetooth is great to connect both keyboard and mouse with a single bluetooth dongle, I'm assuming it will be the preferred technology for the single USB port model-A.

CCitizenTO
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Re: Anyone have wifi dongle without external power?

Thu Jul 19, 2012 2:52 pm

Actually looking at the specs it's respectable range... (https://en.wikipedia.org/wiki/Bluetooth#Uses)

Class 1 = 100mW = 100meters (I'm a bit skeptical of 100m claim myself)
Class 2 = 2.5mW = 10 Meters
Class 3 = 1mW = 1 Meter (I know the wiki article says 5m but many other places say 1m)

Of course it depends on what the weakest link is. If your Pi has a Class 1 receiver but your keyboard is only Class 2 you wont be getting 100m range you'll see maybe 10m. Though if you have two Pi's with Class 1 receivers you might be able to get a decently good range between the two.

donniezazen
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Re: Anyone have wifi dongle without external power?

Fri Jul 20, 2012 7:46 am

mahjongg wrote:What Jbale said is critical, for any USB device on an R-Pi to work two factors must be met, firstly the current consumption of the USB device must be low, at least less than 100 mA, and the second factor is that the device should work with a much lower voltage than is normal for "5 Volt logic", that is much less than the normal 4.75 Volt "5 Volt logic" normally works with.
In practice this means (for the second factor to be true) that we are talking about a "low power USB device" That is a device that uses less than "one USB current unit", with "current unit" meaning 100mA. So the device should use (a lot) less than 100mA, to be able in the calss of devices that will generally work with a lower voltage.
Most USB mice and keyboards are indeed such devices, normally use something like 50mA, and can work with 4.4Volt.

Why is this important? Answer, only because of the polyfuses used in the PI, which are rated 140mA, and have such a high resistance to current that they "steal" output voltage from the USB device (it "Ohm's law")
In fact if the device would use 100mA, then after the fuse, the 5V from the PSU would have dropped to 4.4 Volt! If the current is more than 100mA, there are two problems:
1) The voltage drop will be more severe, so the remaining voltage will be even less than 4.4 Volt, and
2) devices consuming more than 4.4 V are probably not designed as "low power devices", and are less likely to work with just 4.4 Volt.

So for any WiFi adapter to work it must:
use a bit less than 100mA, say just 80mA
and
Can work with just 4.4 Volt

Clearly some WiFi adapters are capable of this, and almost all bluetooth adapters (for wireless keyboards and mice) will use much less current (like 20mA) and should work with 4.4V.
But exceptions may always occur.
On top of that not all WiFi adapters have Linux support, and some have Linux drivers, but these are "closed source" so there is no way to compile them for an the ARM CPU of the R-Pi.
So any widi dongel that will work has to
My TP-Link TN772WN won't work. I am thinking of getting a power hub. Will I help?

I am running my pi on a 2amp supply.

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piglet
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Re: Anyone have wifi dongle without external power?

Fri Jul 20, 2012 8:07 am

I tried my EDIMAX EW-7811UN from the pi directly last night and it worked OK. I've not left it running for long enough to say for sure whether this is a sustainable way to run it.

I have been using it from a powered usb hub, but it starts to fail on the hub after a while with multiple "Failed to read register index 0x00000114" which I attribute (rightly or wrongly) to the USB driver problems noted all over this forum.

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Mr.Dave
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Re: Anyone have wifi dongle without external power?

Fri Aug 31, 2012 11:37 pm

Image

RT5370 - No external power needed

Jawed
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Re: Anyone have wifi dongle without external power?

Sat Oct 13, 2012 5:19 am

I tried to connect my Multimedia Projector, Mitsubishi XD-560U, via WiFi UBS Dongles available in the market, but they didn't work, then i bought one that works below 5 volts. The projector is giving less than 5 volt at its port. It is now running fine :)

zoyo
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Re: Anyone have wifi dongle without external power?

Tue Oct 23, 2012 5:25 pm

Many of you are lucky with EDIMAX EW-7811UN, it seems. Without a powered USB hub I found it unstable. No surprise, however, since:

lsusb -v 2>/dev/null|egrep -i 'bus|maxpower'
Bus 001 Device 004: ID 7392:7811 Edimax Technology Co., Ltd EW-7811Un 802.11n Wireless Adapter [Realtek RTL8188CUS]
(Bus Powered)
MaxPower 500mA

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Dweeber
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Re: Anyone have wifi dongle without external power?

Tue Oct 23, 2012 5:40 pm

All three of my RPI are using either Edimax-EW-7811Un or an Airlink 101 plugged into the top USB port with no real problems. I run headless (no keyboard or mouse) with the second USB port normal open though I do occassionally have a USB thumb drive connected.

Of the 4 WiFi adapters I have 3 work great... one however is much slower than the others so I've taken it out of the mix. With the added support for the RTL8188CUS driver, these work great for me out of the box.
Dweeber A.K.A. Kevin...
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MattHawkinsUK
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Re: Anyone have wifi dongle without external power?

Tue Oct 23, 2012 6:26 pm

Edimax 7811 works for me. Have run it for 30+ hours.

No other USB devices and using Blackberry 700mA power supply.
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