This is the module to get high-speed (40Msps) signal acquisition.

What does it look like?

Information

What is it supposed to do?

The aim of this echOmod is to simulate the enveloppe (or maybe soon the raw signal) that would come from the piezo and analog chain.

How does it work: block diagram

ITF-B_5v->BBB->PRUDAQ->BBB->File
ITF-E_signal_envelope->PRUDAQ
BBB->SPI->TFT Screen

About the module

Pros

Dual-channel simultaneously-sampled 10-bit ADC
Up to 20MSPS per channel (40MSPS total) (but see below)
0-2V input voltage range (DC coupled)
4:1 analog switches in front of each channel provide a total of 8 single-ended analog inputs. (See here for differential input)
SMA jacks for direct access to the 2 ADC channels
Flexible clock options:
- External input via SMA jack
- Internal onboard 10MHz oscillator
- Programmable clock from BeagleBone GPIO pins

Cons

Input signals outside the 0-2V range may damage the ADC
Inputs are DC-coupled
We provide a 1V reference for mid-scale, but it's unbuffered
At 40MSPS the 1GHz ARMv7 only has 25 cycles per sample (and at least 25% of that is eaten by DMA overhead)
Round-robin sampling across the 8 analog inputs is tricky
As the previous section points out, you can buffer samples into the 512MB of main memory, but there's no way to get the samples into storage or off the board at the full 40MSPS data rate

Constraint and limits

The 0-2V limit

The enveloppe signal (0-3.3V) coming from Goblin is clipped beforehands with 2 diodes, giving a 0-1.5V range with easy components.

Testing the analog processing board with the PRUDAQ

Data sampled at 10Msps on the PRUDAQ on both channels.

See the Jupyter notebook In-Out.ipynb

Data is saved here. It's 32Mb of sampling at 10 Msps.

Signal in / signal out

The signal sent in is 50mVpp, the carier is at 2MHz. Linear decrease from t0 to the end.

Details at the enveloppe level

The period of the signal is 2 MHz. The first peak has 1 period, the second 2, height is half of the first peak, and the 3rd has 3 periods, height 1/4th of the first peak.

Learn more

From BeagleLogic:

Learning more about BeagleLogic:

BeagleLogic can be used stand-alone for doing binary captures without any special client software.

 dd if=/dev/beaglelogic of=mydump bs=1M count=1

is sufficient to grab a binary dump, once sample rate has been configured. This can be done via sysfs, but in our case, I just used the onboard 10MHz clock, and selected it with the on-board clock-selection jumper.

Install

The image that I used for this PRUDAQ module was available via Abhishek on google docs
One can also use a eMMC flashed
and read the quickstart,

dd if=./beaglelogic-prudaq-system.img of=/dev/mmcblk0 bs=1M count=1

An interesting read to expend the file system : Read more.

Vitesse d'acquisition

sudo dd if=/dev/beaglelogic of=dual_entry.bin bs=1M

debian@beaglebone:~$ sudo dd if=/dev/beaglelogic of=sonde3V_1.bin bs=1M count=3232+0 records in
32+0 records out
33554432 bytes (34 MB) copied, 0.939505 s, 35.7 MB/s
debian@beaglebone:~$ sudo dd if=/dev/beaglelogic of=sonde3V_2.bin bs=1M count=32 
32+0 records in
32+0 records out
33554432 bytes (34 MB) copied, 0.916971 s, 36.6 MB/s
debian@beaglebone:~$ sudo dd if=/dev/beaglelogic of=sonde3V_3.bin bs=1M count=32 
32+0 records in
32+0 records out
33554432 bytes (34 MB) copied, 0.939741 s, 35.7 MB/s
debian@beaglebone:~$ exit

Cloning the card

For verbose

Install pv dialog

(pv -n /dev/mmcblk0 | dd of=~/mmcblk0.img bs=1M conv=notrunc,noerror) 2>&1 | dialog --gauge "Running dd command (cloning), please wait..." 10 70 0

Not verbose

Creating the compressed image

dd if=/dev/mmcblk0 | gzip > ~/mmcblk0.img.gzip
Unzipping it (Where sdx is your SD card.)

gzip -dc /path/to/image.gz | dd of=/dev/sdx

For a working customized image, follow this link.

Discussions

TODO

Enhance the BBB to transform it into a ultrasound server

DONE

Do the quick check up
Acquire some data
Post some data

People

PRUDAQ people !
Kelu

PRUDAQ acquisition