Raspberry Pi Forums

I haven't played with either of my original rev 1 boards for quite some time; however, I did connect my new rev 2 China made (512MB) board to my Motorola LapDock today. Follows are my observations.

I am powering the Pi via the MicroUSB connection on the LapDock using an unmodified microUSB/USB cable to one of the two USB ports on the Pi. This means I am back powering the Pi and NOT using the microUSB power port on the Pi. Powering this way is safe on the rev 2 boards, correct? On the rev 1 boards I only connected the data lines to the Pi USB hub and powered the Pi with a wall-wart (IE.. never made the y-cable). I also plugged my USB wireless adapter into one of the USB ports on the LapDock and it worked!!! On my two rev 1 boards, I had to disable the wired Ethernet with a command before plugging in the WiFi adapter or the Pi would lock up. If it safe to power the rev 2 Pi through the USB hub, this would eliminate the requirement to make a (data only) y-cable.

Final question, does the current Raspbian download take advantage of the 512MB of onboard RAM yet?

I can only answer the last question. Yes, the latest Raspian has an option on the initial config screen to configure your RAM split.

Update: The Pi does not crash if I plug in my USB Wifi dongle after boot; however, it will NOT complete the boot process until I unplug the USB Wifi. So I guess we need to make sure USB Wifi dongles are not plugged in until after a successful boot.

rrolsbe wrote:I am powering the Pi via the MicroUSB connection on the LapDock using an unmodified microUSB/USB cable to one of the two USB ports on the Pi. This means I am back powering the Pi and NOT using the microUSB power port on the Pi. Powering this way is safe on the rev 2 boards, correct?

I would consider it safe. RasPi rev 2.0 eliminated USB polyfuses F1 and F2 because so many USB hubs out there incorrectly provide upstream power. The RasPi designers figured they might as well give up and go ahead and let the hubs do it. By using upstream USB power instead of RasPi's Micro USB power jack you lose the protection of main polyfuse F3, but you lose that protection with any USB hub that provides upstream power. Lapdock is only going to damage RasPi in the unlikely case that Lapdock's 5V regulator goes crazy and sources excessive voltage. Even then, RasPi still has a zener diode D17 to keep 5V from going too high, at least for a while.

I'm using a RasPi rev 1.0 with my Lapdock. I replaced polyfuses F1 and F2 with low-resistance single-blow 1A fuses and I use a single USB adapter cable to Lapdock for data and upstream power. It works fine.

I also plugged my USB wireless adapter into one of the USB ports on the LapDock and it worked!!! On my two rev 1 boards, I had to disable the wired Ethernet with a command before plugging in the WiFi adapter or the Pi would lock up.

This could be a RasPi software problem rather than a Lapdock problem. With the wireless adapter in a Lapdock port RasPi has to go through two hubs to talk to it. You might try the USB wireless adapter in the spare RasPi USB port, though this could be problematic because of the additional current needed for the wireless adapter. However, on the rev 2.0 you're not having to power both RasPi and the adapter through a micro USB cable and polyfuse F3. If you want to try putting the wireless adapter in a RasPi USB port, check RasPi's 5V at TP1 and TP2 before and after plugging in the adapter to make sure it's not drawing too much current through your USB adapter cable.

johnbeetem wrote:You might try the USB wireless adapter in the spare RasPi USB port, though this could be problematic because of the additional current needed for the wireless adapter.

Check the adapter's power spec before trying this. If it's more than 200 mA or so, you probably shouldn't, though I welcome other opinions.

I replaced my Rev1.0 board on my lapdock with a rev 2.0 512Mb board and have had no problems with the switch.
The 512Mb ram is recognized and the netgear WG111 Rev2 WiFi adapter is also working fine now if a could find a browser on the Raspi that worked better in the forums I would also post more often with it.

Chromium does not show new post nor does midori and netsurf shows the new posts button, but typing in the post section is not working right.

I have not tried plugging in hardwired network while the WiFi adapter is plugged in with the new board, but in my older boards it did not act nicely when both were attached.

Vindicator wrote:I replaced my Rev1.0 board on my lapdock with a rev 2.0 512Mb board and have had no problems with the switch.
The 512Mb ram is recognized and the netgear WG111 Rev2 WiFi adapter is also working fine now if a could find a browser on the Raspi that worked better in the forums I would also post more often with it.

Thanks for the feedback. Is the WiFi adapter in a Lapdock USB port or the spare RasPi USB port?

I read somewhere, that their is a problem regarding the raspi ethernet adapter in combination with lapdock + wifi. Their is also a small work arround for this. ( which just disable the ethernet on the pi )

I just received the latest lapdock designed for the newer (than the original Atrix - there's now an Atrix HD model) Motorola Droid Bionic. As noted elsewhere previously, the Bionic lapdock only different from the Original Flavor Atrix lapdock in that the phone cradle micro-HDMI and micro-USB connectors are each rotated 180 degrees around the vertical axis from the orientation in the Atrix lapdock, and the cradle has a slight bulge along its upper edge (rear edge when rotated up into phone dock orientation) to accommodate the apparently slightly thicker Bionic (or the micro-HDMI and micro-USB connectors are at a different offset from that on the original Atrix). The result of the reversed connectors is that if the micro-HDMI and micro-USB cables/adaptors had to be trimmed along the back and side edges in order for the connectors to fit next to each other, they're going to have to be trimmed again along the opposite sides - biiiig disappointment

The Bionic lapdock boots fine with both the 256 and 512 MB Pi boards of all revs, as long as the power is routed properly to the micro-USB or USB ports depending on the board rev or mods to the USB polyfuses. It also works fine with any of the several WiFi dongles I have when they're plugged into a lapdock USB port and the latest version of Raspbian (2012-10-28) is being used.

I really like the Atrix/Bionic lapdocks because they're both made of aluminum and are just absolutely rock-solid physically and electronically, while being very light (closer to the weight of an iPad than even a netbook). Reportedly, the newer, numbered models (100, 300, etc.) are made primarily of plastic, and those would not be nearly as strong as the aluminum models. I'm going to buy as many of the Atrix and Bionic lapdocks as I can for the schools I assist when I can find them at the lowest prices (~$50 with free UPS Ground shipping that takes 10 ~ 14 days). It's such a convenient, lightweight form-factor including a display, good-sized trackpad, keyboard, two-port USB hub, and 6+ hour battery (depending on types of apps run and their usage).

johnbeetem wrote:

Vindicator wrote:I replaced my Rev1.0 board on my lapdock with a rev 2.0 512Mb board and have had no problems with the switch.
The 512Mb ram is recognized and the netgear WG111 Rev2 WiFi adapter is also working fine now if a could find a browser on the Raspi that worked better in the forums I would also post more often with it.

Thanks for the feedback. Is the WiFi adapter in a Lapdock USB port or the spare RasPi USB port?

I have tried both (RasPi USB/Lapdock USB) on the 512MB's with a linksys wireless adapter (WUSB54GC) and it worked either way. The 512MB RasPi USB port still will not power the Seagate USB 2.5" HDD.

Thanks for the feedback. Is the WiFi adapter in a Lapdock USB port or the spare RasPi USB port?

I have my USB adapter plugged directly into the Lapdock didn't want to push my luck plugging it into the second port of the Pi. Also an update to my update, I was NOT using the latest Raspbian when I discussed booting problems with the USB Wifi adapter plugged in. The latest Raspbian version works great with my Wifi dongle on the rev 2 board, maybe I should try it on the rev 1 boards?

Now if I could get the any browser/configuration to allow me to read https gmail without being painfully slow, I would be a happy camper.

With the additional 256MB of RAM, seems like there should be a way to speed things up considerably?

The latest version of Raspbian appears to create 100MB of swap, is this a swap file? if so, is it located/mounted on the SDHC card or in RAM? There is not a swap partition on the SDHC card and if there where it would be SLOW.

I plan to migrate the SDCARD partition 2 contents to an ext4 partition on a LapDock USB attached spinning drive. This drive also has a swap partition which I plan to use.

Might make sense to create a RAM disk and place the browser binary and/or create swap in part of the additional 256MB of RAM? I run Puppy LInux on an x86 machine with the entire OS running out of RAM via a Squash File System .sfs. typically without a swap file; however, having only 512MB of RAM probably would require a swap file/partition to keep the Pi from locking up when it exhausts the RAM resources. What browser/configurations are other forum members using that give good performance rendering https web pages (IE... https://mail.google.com as an example)

Sorry for being to long winded...
Regards, Ron

My lapdock has been sleeping for months as I intended to use it with a MK802 a first and [...], but now that i have a rev. 2.0 Pi I'm gonna use it with the lapdock i think - i'm waiting for the adaptators from china and uk...

Regarding lightweight browsers, luakit seems to have my preference for now, i just tried gmail though and it takes a long time to load it but after that opening emails is more decent. Tho I think I'm gonna look for a lightweight IMAP email client to use on the Pi for gmail.

Regarding the swap I was just looking into it, it's a swapfile managed by dphys-swapfile, it's 100mb by default it seems, but a little man dphys-swapfile should tell you how to set up a config file.

rrolsbe wrote:Might make sense to create a RAM disk and place the browser binary and/or create swap in part of the additional 256MB of RAM?

Creating a RAM drive (it's not a disk, of course) for swap is completely self-defeating and will slow things down even further. Swap space has to be on external storage outside of RAM (e.g., USB flash memory, USB hard disk, USB solid-state drive (SSD), etc.) as its purpose is to extend the memory address space beyond the limits of RAM, with that extended memory space being called virtual memory.

Putting the browser executable code in a RAM drive may or may not make the browser faster, depending on what else is running in the foreground or background. A better option may be to use the "nice/renice" utilities to increase the precedence of the browser. There are 41 precedence levels, ranging from -20 at the highest level of precedence, down through 0 (medium precedence), to +20 at the lowest level. If you're starting the browser (or any program), the command syntax is:

sudo /usr/bin/nice -n -20 program_name

where program_name is /usr/bin/netsurf, /usr/bin/dillo, /usr/bin/midori, /usr/bin/chromium, /usr/bin/iceweasel, or whatever browser or other program for which you want to control the scheduling precedence. The operating system scheduler uses this precedence that nice sets as an input, not an absolute directive to ensure that users don't clobber system-level processes to the point where critical tasks such as file reads and writes, memory allocation and deallocation, network communications, etc., can't be carried out successfully. Note that I use the term ”precedence" and not "priority" as many people do because, historically, "priority" is a level of precedence in military communications, which also includes "routine", "operational immediate", and "flash".

If a program is already running, it's possible to use "renice" to change its precedence if you use ps -axl | grep program_name to find the process ID (pid) of the program (where program_name is midori, dillo, netsurf, chromium, icewasel, etc.), with the command syntax:

sudo /usr/bin/renice -n -20 -p pid

where pid is the number of the process ID of the program you found using the ps -axl command (ps -axl means "list processes being executed in long format including details". The -20 can be anything from -20 to 20 from highest precedence to lowest as discussed above.

Hope this helps.