zkimal
Posts: 2
Joined: Sun May 27, 2012 2:21 am

wireless access point battery powered

Sun May 27, 2012 2:42 am

i still don't have a raspberry pi but i was thinking of giving some wireless connection to a robot or something by connecting the raspberry pi via Ethernet to a wireless router modified to work with a 12V battery who also via an lm7805 gives power to the raspberry pi so you can have a mobile device with WiFi connection and don't worry about the drivers and other stuff

what would it by the pros and cons of this also if someone know about a low power WiFi router ?

error404
Posts: 351
Joined: Wed Dec 21, 2011 11:49 pm

Re: wireless access point battery powered

Sun May 27, 2012 5:54 am

This is feasible but it's going to use a lot more power than just attaching a WiFi dongle to the Pi. Also LM7805 is a terrible choice for the Pi, it's very inefficient and will need a large heatsink; powering a Pi at ~500mA from 12V it will dissipate over 3.5W while supplying only 2.5W to the load. You will waste more of your battery capacity than you use. I'd suggest a switching regulator instead like the cheap MP2307 or LM2596 modules that are on eBay.

ASUS WL-330gE is a suitable device if you do want to do this.

zkimal
Posts: 2
Joined: Sun May 27, 2012 2:21 am

Re: wireless access point battery powered

Sun May 27, 2012 10:10 pm

i know that a router is going to consume more power than a WiFi dongle but is a Ethernet connection so is no need for drivers also you can control the move of the raspberry pi via a laptop without an external access point just making a remote desktop session also the ASUS WL-330gE consume 5V 1A just like the raspberry pi so a better VRM like the MP2307 or LM2596 it will be needed for this thanks for the info.

bircoe
Posts: 37
Joined: Wed Jul 27, 2011 9:43 pm

Re: wireless access point battery powered

Tue Jun 12, 2012 12:34 pm

I'd go with a USB dongle like error404 suggested... it will be easier in the long run, having a separate access point just increases your power consumption and makes another point of failure... well 3 if you count the PSU and associated cabling.

Setting up a USB dongle under Linux is relatively easy (plus it's powered by the Pi), I've never done it before and I've just got my Asus USB-N10 (Realtek RTL8191SU chipset) up and running in about 10 minutes.

Now that it's up and running my next step is to make it behave like an access point, this will be exactly what you want, it will be the host and clients like your phone or laptop can connect to it's network.

bredman
Posts: 1415
Joined: Tue Jan 17, 2012 2:38 pm

Re: wireless access point battery powered

Tue Jun 12, 2012 1:18 pm

Most USB WiFi devices cannot work in AP mode. But they can all work in ad-hoc mode. You don't need an Access Point to connect your PC to the RPi over ad-hoc WiFi.

Adding the drivers in Linux is actually easier than Windows, you probably need to enter one of the following commands
sudo apt-get install firmware-realtek
sudo apt-get install firmware-ralink
if you don't need to worry about network security.

Much easier than Windows, where you have to search the internet, hoping you find the right driver.

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