Tag Archives: raspberry pi

How to tell if PL-2303HX ( PL-2303 ) is 3.3v or 5v

If you have a USB adapter and would like to use it when working with Arduino or Raspberry Pi you may wonder if it is safe to use with a 3v3 system. Purchasing these on eBay can be cheaper than buying from someplace like Adafruit but the listings often have no documentation on if the chip can be used with 3.3v devices. You can measure some of the pins to make your own determination. The unit I was working with several pins labeled: I measured voltage between the GND pin and the TX pin which gave around 1.8 – 2.5V without any data being transmitted. When I sent data to the device the voltages went intermittently to around 3.3 volts or maybe 3.4 volts. But I wanted to make sure that the chip was actually setup for 3.3v and so I found the datasheet for the PL-2303HX Make sure to get the correct datasheet for the chip you have – some of the chips are slightly different, like the HXD version. On page 11 of that datasheet it showed the pinout diagram – notice the small circle indicating “pin 1” which should correspond to the small dot on the actual chip: Pin 4 is labeled VDD_325 and the note says: RS232 VDD. The power pin for the serial port signals. When the serial port is 3.3V, this should be 3.3V. When the serial port is 2.5V, this should be 2.5V. The range can be from 1.8V~3.3V. Use this information at … Continue reading

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Occidentalisv02.zip – Access Denied Error

If you’ve tried to download the Occidentalisv02.zip file – a.k.a “Occidentalis v0.2. Rubus occidentalis” – from Adafruit at adafruit-raspberry-pi.s3.amazonaws.com, possibly using something like wget http://adafruit-raspberry-pi.s3.amazonaws.com/Occidentalisv02.zip you may notice an Access Denied error like this one: <error> <code>AccessDenied</code> <message>Access Denied</message> <requestid>9382794827938798273</requestid> <hostid> QWNjZXNzRGVuaWVkT2Nj-aWRlbnRhbGlzdjAyLnppcA </hostid> </error> The file has not been removed, the download IS STILL THERE – you just have to visit their webpage to download it because they have referrer checking enabled. If you are still having trouble from their webpage, try a different web browser and it should work.

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Solved: Raspbian with Edimax EW-7811UN WiFi Adapter and 802.1X authentication or WPA shared key authentication

Recently I wanted to set up Wireless (Wi Fi) Ethernet 802.1X authentication on a Raspberry Pi with Raspbian “wheezy” 3.6 (version 3.6.11 actually) and the Edimax EW 7811UN WiFi Adapter. I had read a lot of posts about having trouble with the Edimax adapter – and how you would need to replace the driver file cfg80211.ko and / or rebuild one from the source code. This simply wasn’t true for me – the device worked very well right out of the box – with a few small configuration changes which I will share with you. Here is my setup: Raspberry Pi was a “Pi Model B” with the 512MB of memory Downloaded Raspbian wheezy from the downloads site – version was `2013-05-25-wheezy-raspbian.zip1 Created a SD card with the image EW-7811UN WiFi Adapter Notes: If you boot up the Pi and then plug in the EW-7811UN WiFi Adapter directly to the Pi, it will likely crash / reboot the Pi. This is not a problem with either device, but the EW-7811UN WiFi Adapter requires a lot of power and so it underloads the Raspberry Pi’s circuits and causes this behavior. If you have a powered USB hub (in my case my monitor) and plug / unplug the EW-7811UN WiFi Adapter then you will not cause the system to crash / reboot I did my initial bootup of the Pi without the EW-7811UN WiFi Adapter plugged in I did not select any special options on the first boot – I just went … Continue reading

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Command To Shutdown And Power Off Raspberry Pi

For the Raspberry Pi: sudo poweroff shuts down and sudo reboot reboots The default username is pi and the default password is raspberry

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[solved] raspberry pi: A window manager is already running on screen

A while ago I did a post about using remote desktop with raspberry pi – that was a fun, successful project. Now it’s been a while since I had to do the setup on a new raspberry pi machine and when I tried to remote desktop to my new pi I got this error: A window manager is already running on screen Well that’s no good! The problem turned out to be fairy easy to resolve: I was sshing into the pi as the root user ssh [email protected] -X but I should have been connecting as the pi user (ssh [email protected] -X) – once I got that straightened out and ssh’ed in and ran lxsession the GUI / remote desktop for pi fired right up!

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Raspberry Pi – shipping delay

Dear customer, Thanks again for your Raspberry Pi order. We are busy working with the suppliers who provide components for your Raspberry Pi to ensure you receive your order as quickly as possible. Since receiving your order, we have been advised that our next batch of approximately 40,000 Raspberry Pi’s will now be arriving during September, with further deliveries expected in October. This delay is due to the very high level of demand on the core Raspberry Pi processor chip. Unfortunately, this means that your order could be delayed by up to 8 weeks, although we are trying to reduce this as much as possible. We have updated the delivery schedule displayed in our FAQ’s and on the Raspberry Pi forum. As soon as we receive confirmation of any improvements from our manufacturers, we will advise you. Please accept our apologies for this delay and be assured we are doing everything we can to ensure the fastest possible delivery of your Raspberry Pi. Yours sincerely, RS Components & Allied Electronics

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Remote Desktop to Raspberry Pi from OS X w/ ssh XForwarding

Can you already ssh into your raspberry pi? In short, you will need to make sure you have a public key in the /home/pi/.ssh/authorized_keys directory. The directory should be chmod 700 and the file chmod 600. Good. If not see the notes below. You can then SSH to the box with something like: ssh [email protected] -i /path/to/private.key -X The -i option will specify your private key and -X will turn on X Forwarding. Once you’ve logged in you should be able to run lxsession to start the Lightweight Desktop (LXDE): If you can’t already SSH into your pi, fusionstrike has some notes on how to set that up. One more note: don’t try and do this as the root user. You may get some errors about A window manager is already running on screen – do it as the pi user as I mentioned above.

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