Raspberry Pi and the unresponsive miner

[Flame Soulis]

After building a simple case for my Raspberry Pi to live its life as a bitcoin miner, I hooked it up with 2 Eruptors and saw that one was being faulty, which I suspected was the case anyway. After ordering another, I swapped the bad one for the new one and was greeted with an unusual situation.

Now my pi, with a HUB attached mind you, will only utilize ONE of the miners. Both miners are detected properly and I had the settings set properly, yet only one appears to get the job done and the other idles indefinitely (green light remains on), even though it was working fine before. Confused, I removed the new miner and restarted CGMiner. Alas, it was working fine. Replaced it with the other, and behold, it had no complaints. But the moment both are in the same HUB, the newer one only works and the other takes the backseat.

Figuring maybe it was a bug with 3.1.1, I downloaded and recompiled 3.4.3 of CGMiner. I was actually impressed with the hotplug ability and this made testing easier. Upon running the newer version, it was the same story: Old one doesn't do a thing, but the newer one does. Removed the newer one, older one begins to work. Put the newer one back in and the older one idles again. The hash rates do show the correct numbers if both were working and if they are alone, and even plugging in the faulty miner shows the correct results; even the faulty one begins to actually mine (granted, this just gives HDW errors, but at least it is getting something to do).

So now I am at a loss. I am running simple Raspian and have the Pi and the 2 miners powered by a 2A USB 2.0 HUB. I am not using WiFi or any other devices on the Pi other than the HUB itself (which also powers the Pi). Does anyone have an idea what is going on?

[Zanatos666]

I would guess that you truly arent getting 2.0A out of your hub power and thus your Pi is pulling too much power.  Get a separate AC adapter for your Pi and try the BE in the hub by themselves.

[vm1990]

I would guess that you truly arent getting 2.0A out of your hub power and thus your Pi is pulling too much power.  Get a separate AC adapter for your Pi and try the BE in the hub by themselves.

agreed. not enough power for the hub to power the pi and 2 block erupters.... best way would be a dedicated psu for the pi

[Flame Soulis]

I'll have to give it a try, though what has me confused is if I have the 3 miners active, the 'good' one still idles yet the other two work fine. The power source is a PSP charger (5v, 2A). I'll give the Pi it's own source in a sec and try that to rule out power issues.

[Flame Soulis]

Okay, I have a bit more info now:

First, I unplugged the Pi from the Hub, which the Pi could STILL power on even when not connected due to the 5v rail. Even with that, I plugged the Pi into another charger which gives 2A solid. Taking a volt meter to the miners, when 1 miner is idling, I get 5.2v. When operating, it goes down to 5.0v. With two plugged in, both report 5v idling and 4.95v mining. With the third (faulty) one, the value goes down to 4.5v with all 'mining', though the one good one continues to idle. Upon checking the voltage on the two working ones (aka, not idling), they were reporting the same voltage and yet were working fine (no hw errors except from the one that is faulty for obvious reasons).

So I'm now at a loss: even with the Pi being powered separately (with the Pi in the Hub, all results are the same where the voltages were about 0.2-0.3v lower), the one miner continues to idle. In CGMiner, it is showing the speeds correctly (3: ~905Mh/s; 2: 666Mh/s; 1:320Mh/s), but on the pool's end, it only acts as though 1 is working (since one is faulty and results with errors and maybe 1 good result every 100 errors).

[RaTTuS]

how did you build cgminer ?
...
this is how I do it ...
load up raspbian on your RPi
then
sudo apt-get update && sudo apt-get upgrade -y
sudo apt-get install build-essential libusb-1.0-0-dev libusb-1.0-0 libcurl4-openssl-dev libncurses5-dev libudev-dev
wget http://ck.kolivas.org/apps/cgminer/cgminer-3.5.0.tar.bz2
tar xf cgminer-3.5.0.tar.bz2
cd cgminer-3.5.0
mkdir libusb
cd libusb
wget http://sourceforge.net/projects/libusb/files/libusb-1.0/libusb-1.0.16-rc10/libusb-1.0.16-rc10.tar.bz2
tar -xf libusb-1.0.16-rc10.tar.bz2
cd libusb-1.0.16-rc10
./configure
make
cd ../..
LIBUSB_CFLAGS="-I./libusb/libusb-1.0.16-rc10/libusb" LIBUSB_LIBS="./libusb/libusb-1.0.16-rc10/libusb/.libs/libusb-1.0.a -ludev" ./configure --enable-icarus --enable-bitfury --disable-opencl
make
sudo make install

[madcratebuilder]

You should try Minepeon, made for mining with the Rpi.  You need to power the Pi with it's own psu, you do not want to back power through the usb ports.  Use a good hub, I like the Rosewill hubs, the 10 port rhb500 well run 8 eruters.  The 7 port D-Links well only run 4 erupters.  You need .5 amps per erupter.  Measuring volts does nothing, you need amps or watts+volts and convert to amps.

This 40 erupter mine runs at 168 watts, uses bfgminer in Minepeon, rock solid at 13300 Mh/s, 13.3Gh/s  Cgminer works well with 20 or less erupters, for more than 20 bfgminer is the way to go.