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WiFi dongle (Ralink RT5370)

Tue Oct 16, 2012 9:04 am

I have bought a Ralink RT5370 WiFi dongle which i have managed to get to work but i have some issues which i would like to ask about.

Some background :
I am using a Raspberry Pi 2011.12 which does not have any Polyfuses on the USB ports. I am also using a iPad 2.1A charger for powering the Pi. The pi has a ethernet cable connected and a wired usb keyboard.

The issue
Most of the time when the Pi is running and i am connecting the WiFi dongle into the USB port the Pi rebooths without any message. This indicates an power issue right ? Would i see this spike of power draw on TP1 and TP2 ?

I have tried to use an powered usb hub and have connected/disconnected the WiFi dongle at least 10 times without any reboot so it does seem power related.

Is it even possible to use this kind of dongle on the Pi itself without a powered USB hub ? I really don't like to have another box running and cosuming power. My guess is that the iPad power supply is not good enough ? Can one recommend an good power supply which delivers the needed power for this purpose ? It would be nice if there was one from farnell.


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Re: WiFi dongle (Ralink RT5370)

Tue Oct 16, 2012 7:57 pm

Code: Select all

sudo lsusb -vv
show me the result
Cogito ergo sum

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Re: WiFi dongle (Ralink RT5370)

Tue Oct 16, 2012 8:30 pm

This is actually the downside of removing the polyfuses.

Because the polyfuses are removed, the USB port is connected directly to the 5 volt power rail. When you connect some power-hungry USB device (such as a WiFi dongle), this causes a temporary drop in the voltage.

There are three fixes to this problem
1. Use a powered USB hub (as you have found by yourself)
2. Attach a small capacitor across the power lines of the USB socket.
3. Put the WiFi device into the socket and don't ever remove it.

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Re: WiFi dongle (Ralink RT5370)

Sun Feb 24, 2013 2:02 pm

I have a Pi 2011.12 as well...if I am correct it was built without polyfuses on the USB ports? As hard as I look I am only seeing one polyfuse on my board...?

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