Raspberry Pi version A?


 
M

M Miller

TVWBB Fan
Hello everyone!

I stumbled on this article in my Twitter feed.

The version A board apparently consumes 1/3 the power of the version B.

This would be quite a nice improvement for smoking in a low-power situation, when it's finally available. :)
 
Yeah I had initially hoped to use the A version exclusively. I didn't realize it was going to be over a year before they were available. Heck, even the B models are still somewhat scarce.

Thanks for the link, I'd been checking http://raspberrypi.org/ every couple of days waiting for the US release.
 
Did anyone else manage to snatch one up? I was lucky enough to get one for $25, and they only charged me... $9.52 in tax and shipping for USPS slowest 5-10 day shipping.

EDIT: Turns out they only pre-authorized my credit card for $73, the shipping was a reasonable $5.63
 
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Two days later and I have a model A. I pulled the SD card out of my model B and stuck it in and moved the WiFi adapter. Fired it up and it worked just like a B. I even reflashed a default image and it worked fine.

The composite video RCA jack seems to be slightly larger, or maybe I have forgotten how tight the pieces fit together, but it doesn't fit very well at all if you leave the jack on.

All in all, if you can get your hands on a model A, it seems to be everything HeaterMeter needs, just $10 cheaper.

EDIT: I kinda want to say it is even better than a Model B. Web page load times show less latency. I can run HeaterMeter at 115200 baud without any serial checksum errors or buffer overruns. It boots a second faster. This thing is a win all around.
 
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How do you do the initial wireless setup without a network port? Do you need a model B to do that portion then move the card to the model A?

dave

Bryan Mayland said:
Two days later and I have a model A. I pulled the SD card out of my model B and stuck it in and moved the WiFi adapter. Fired it up and it worked just like a B. I even reflashed a default image and it worked fine.

The composite video RCA jack seems to be slightly larger, or maybe I have forgotten how tight the pieces fit together, but it doesn't fit very well at all if you leave the jack on.

All in all, if you can get your hands on a model A, it seems to be everything HeaterMeter needs, just $10 cheaper.

EDIT: I kinda want to say it is even better than a Model B. Web page load times show less latency. I can run HeaterMeter at 115200 baud without any serial checksum errors or buffer overruns. It boots a second faster. This thing is a win all around.
Click to expand...
 
You can just manually edit the config files:
Code: 
# Add to /etc/config/network
config interface 'wwan'
        option proto 'dhcp'
# Edit /etc/config/wireless
        option disabled '0'
config wifi-iface
        option network 'wwan'
        option device 'radio0'
        option ssid 'mywireless'
        option encryption 'psk2'
        option mode 'sta'
        option key 'wifikey'
I'm going to make a script that will be on the image though because I always forget what the name of the options are. Something like so you can do `wifi-client mywireless wifikey` and it will set it up for WPA2 client mode. Maybe a way to a scan and select the network to join from the list, but I don't know what options are available for interactive shell scripting.
 
You could but that still wouldn't give you a web interface so you'd be stuck manually editing the files which can be difficult for someone not familiar with vi or what values need to be set.
 
Bryan, above you say that the A model is faster, given that the base hardware is the same, could this be due to not having to drivers loaded for the ethernet? What would you attribute this to?
 
I'm not sure. I know that the way the ethernet chip in the B is connected to the single USB connection on the CPU and the USB ports are actually connected through a USB hub built into the ethernet chip. In the A the physical USB port is directly connected to the CPU. That could have something to do with it. As an example, the LinkMeter configuration page loads in 600-700ms on the model B, and 250-350ms on the model A.

I need to swap the WiFi adapters between the two and see if that's what the difference is though (even though they're both the Edimax model).

EDIT: And that's what it is. I have 2 of the Edimax dongles and one is just faster than the other. I even tried swapping the physical locations of the 2 rPis and one is always still slower. The model A still boots faster, 16.8 seconds to wifi up and usable on the A versus 17.7 seconds on the B.
 
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For my own reference later, the Model A with HeaterMeter pulls about 125mA on the 12V line at idle with the switching 5V converter (the standard part) and 145mA when the wifi is transmitting. Connected to a standard LM7805 5V linear regulator, it pulls closer to 300mA at idle and 410-450mA on transmit. An LM7805 does appear to be able to be used but it must be heatsinked, and even then it gets pretty hot burning 3.5W.
 
Bryan Mayland said:
I'm not sure. I know that the way the ethernet chip in the B is connected to the single USB connection on the CPU and the USB ports are actually connected through a USB hub built into the ethernet chip. In the A the physical USB port is directly connected to the CPU. That could have something to do with it. As an example, the LinkMeter configuration page loads in 600-700ms on the model B, and 250-350ms on the model A.

I need to swap the WiFi adapters between the two and see if that's what the difference is though (even though they're both the Edimax model).

EDIT: And that's what it is. I have 2 of the Edimax dongles and one is just faster than the other. I even tried swapping the physical locations of the 2 rPis and one is always still slower. The model A still boots faster, 16.8 seconds to wifi up and usable on the A versus 17.7 seconds on the B.
Click to expand...

I'm needing to purchase an adapter and noticed on Amazon that they have a EW-7811UnR2, which I'm guessing is a Rev. 2 version of the EW-7811Un. ???

http://www.amazon.com/gp/product/B00BFRKUJ8/?tag=TVWB-20

Any downside (compatibility issues) with purchasing this versus a EW-7811Un?

Edit: Bryan, you should include your Amazon affiliate link in your signature as a convenience for those of us who would like to "contribute".
 
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