I have been accessing my headless Beaglebone Black via SSH through my local
home network from a Windows machine quite nicely for several weeks. It is
running Ubuntu 13.04 (GNU/Linux 3.8.13-bone28 armv7l). But I wanted to get
it working through WiFi, so that I could start work setting it up as the
heart of a 4WD rover project.
I should probably also mention the Beaglebone is connected to a quality
bench power supply that can supply 20amps.
First I tried a Netgear N-300 adapter, which uses the Broadcom chip
BCM43231. After not finding any success stories about anyone using one of
these adapters on an Ubuntu Beaglbone, I decided to order Adafruit's #814
WiFi adapter, which uses the RTL8192CUS chipset. Adafruit shows how to use
it with Angstrom but says it may not work with the 3.8 kernel. But that
didn't stop me from ordering it, as I thought I would have a good chance of
finding a way to use it with Ubuntu and my 3.8.13 kernel.
Long story short - I was able to rebuild the driver and get it working just
fine with a connected monitor and keyboard. Both the keyboard and WiFi
adapter were connected through an unpowered Targus ACH114 (4) port hub to
the Beaglebone. By "working just fine" I mean I could SSH connect to it
from my Windows machine, I could access external web sites, etc.
So next it was time to go headless again. That meant plugging the WiFi
adapter directly into the Beaglebone without the hub, since I didn't need
to plug in a keyboard. This is where the flaky part comes in... it is only
intermittently accessible, as in maybe 1 out of 20 attempts. It just times
out with no response most of the time.
Eventually I realized it works just fine plugging the WiFi adapter back
into the unpowered hub and then into the Beaglebone, but still headless
without a monitor or keyboard. Now that seems very strange that the adapter
works going through an unpowered hub but not directly plugged into the
Beaglebone.
So, I decided to try another small 4 port hub, a Belkin F5U404. It can be
powered or not. But guess what? It doesn't allow access powered or not. In
fact it doesn't seem to be compatible with the Beaglebone at all.
Ok, to wrap this little story up... It did work often enough without the
Targus hub to get a lsusb -v report, which is pasted below. I would have
pasted a report with the hub, but it is identical. Both show the WiFi
adapter needs 500ma.
Bus 001 Device 002: ID 0bda:8176 Realtek Semiconductor Corp. RTL8188CUS
802.11n WLAN Adapter
Couldn't open device, some information will be missing
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 2.00
bDeviceClass 0 (Defined at Interface level)
bDeviceSubClass 0
bDeviceProtocol 0
bMaxPacketSize0 64
idVendor 0x0bda Realtek Semiconductor Corp.
idProduct 0x8176 RTL8188CUS 802.11n WLAN Adapter
bcdDevice 2.00
iManufacturer 1
iProduct 2
iSerial 3
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 46
bNumInterfaces 1
bConfigurationValue 1
iConfiguration 0
bmAttributes 0x80
(Bus Powered)
MaxPower 500mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 4
bInterfaceClass 255 Vendor Specific Class
bInterfaceSubClass 255 Vendor Specific Subclass
bInterfaceProtocol 255 Vendor Specific Protocol
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0200 1x 512 bytes
bInterval 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x02 EP 2 OUT
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0200 1x 512 bytes
bInterval 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x03 EP 3 OUT
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0200 1x 512 bytes
bInterval 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x84 EP 4 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 1
I did also try to measure the current being drawn by the Beaglebone Black
with the WiFi adapter plugged into the hub and working. It seems to average
between 350 and 450ma. Of course that was with a digital meter and would
not reflect higher current spikes.
Does anyone have any ideas? This is going to look silly mounted on my rover
with a little usb unpowered hub just to make it work!
Thanks
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