QBone - Building

Parent Category: Projects Category: QBone Written by Administrator

Here are some hints how to build a QBone and test it.

Prepare the BeagleBone's SDcard

Generation

Normally you receive a programmed SDcard with the QBone kit. To make a backup of it, G**gle for "clone SDcard" and follow instructions.
The "clone" consists of reading the given SDcard into an image file, then writing that file to a new card.
On Windows 10 I use "win32diskimager" for convenience.

Under Linuxes its a more complicated call to "dd".  Example run for writing an SDcard from a zipped image file "qbone_sdcard_2018_11_21.dd.gz":

1. Plug a new sdcard of at least 16GB into your card reader. After recognition the desktop file explorer may pop-up some window.

2. Determine the Linux SDcard device:

joerg@vmubuprog:~$ dmesg | tail
[   45.200662] usbcore: registered new interface driver usb-storage
[   45.204700] usbcore: registered new interface driver uas
[   46.199822] scsi 33:0:0:0: Direct-Access     Generic  STORAGE DEVICE   0903 PQ: 0 ANSI: 6
[   46.201107] sd 33:0:0:0: Attached scsi generic sg2 type 0
[   46.482076] sd 33:0:0:0: [sdb] 62521344 512-byte logical blocks: (32.0 GB/29.8 GiB)
[   46.488105] sd 33:0:0:0: [sdb] Write Protect is off
[   46.488108] sd 33:0:0:0: [sdb] Mode Sense: 21 00 00 00
[   46.494056] sd 33:0:0:0: [sdb] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
[   46.524458]  sdb: sdb1 sdb2 sdb3 sdb4 < sdb5 >
[   46.544925] sd 33:0:0:0: [sdb] Attached SCSI removable disk
joerg@vmubuprog:~$

The output above means that the raw SDcard is "/dev/sdb"

3. To write the zipped image onto the card type something like:

joerg@vmubuprog# sudo -s
[sudo] password for joerg:
root@vmubuprog# gunzip <qbone_sdcard_2018_11_21.dd.gz | time dd of=/dev/sdb bs=1M
13+360271 Datensaetze ein
13+360271 Datensaetze aus
15931539456 Bytes (16 GB) kopiert, 828,463 s, 19,2 MB/s
0.00user 9.66system 13:48.46elapsed 1%CPU (0avgtext+0avgdata 3232maxresident)k
200inputs+31116288outputs (1major+350minor)pagefaults 0swaps

This make take some time.

Hostname on SDcard

Typically the BBB is accessed via Ethernet and will appear in your home network under its "hostname".

The initial network name of the BBB is "qbone". If you use multiple QBones, each must get a different name. The hostname is found on the SDcard filesystem at /etc/hostname. You can edit this only the Ubuntu host: re-plugin the SDcard, navigate to /media/<something>/etc,  do a "sudo nano hostname".

Login later with "root/root". 

Be aware that you can not boot from the SDcard until BBB is plugged into QBone board!

 

Populate the board

The populated board looks like this (click to enlarge):

qbone frontal

 Solder best in that order:

  1. SMDs are presoldered. CPLDs come preprogrammed.
  2. flat parts: SIL sockets.
  3. medium high parts: capacitors, IC sockets, switches and the relay.
  4. high parts: pin headers. Only a minimal subset of all the pinheaders is necessary for normal operation, the others are debugging.
  5. LEDs. Anode left toward the "QBone" label.
  6. Plug ICs and resistor packc into their sockets. Resistor values printed onto the board may not be valid! Make the 0-Ohm restisor pack yourself with help of the special IC-socket pinheader.
  7. Make BBB adapter, see below

 

Mount BBB onto PCB

Two special parts are used to fit the BeagleBone vertically into a DEC card space:

bbb mounted top

bbb mounted back

Soldering reduced pinheaders onto spacer PCBs

The pin headers have plastic strips, you get them pushed to one end. The trick is to use the BeagleBone itself as soldering template:

bbb mount pinheaders 01 bbb mount pinheaders 02
bbb mount pinheaders 03 bbb mount pinheaders 04
bbb mount pinheaders 05 bbb mount pinheaders 06
bbb mount pinheaders 07 bbb mount pinheaders 08

Mounting the spacer PCBs

The little spacer PCBs sit pickyback on the main PCB. The trick here is to align them and solder through both PCBs at once. This is suprisingly easy, at least if you fill the metalized PCB holes with flux. Align the two stacked PCBs with the BBB and temporarily pinheaders.

bbb mount spacer 01 bbb mount spacer 02
bbb mount spacer 03 bbb mount spacer 04
bbb mount spacer 05 bbb mount spacer 06
bbb mount spacer 07 bbb mount spacer 08

Just remember to use double length of solder and heat more than the double time.

Cave at: Sometimes your solder may not flow through both PCB layers, resulting in an open contact.

bbb mount spacer failure


When that happens: do not resolder from the clean side .
Always resolder from the side you worked on already
, suck off the old solder if necessary.
If you try to close the bad junction from both sides

If you don't feel the need to use a circuit beeper, then you're doing right.

 ***

Now continue with tests ...