I just got an interesting mechanical probe, a Bard Site Rite - piezo at 7.5MHz. The plug is quite simple, and digging into the cable yields 2 pairs of cable, one coax, a bigger cable with two "big" cables. I've made sure it's a mechanical probe. The aim is to try and see if I can connect it to my board and get an image.
Good point for this probe is that it unscrews nicely.
and even better, it has changeable heads!
I assume two pairs of cables are for motors / actuators, coax is for the signal coming back (hence the bead). But how can I see that on the pins above?
Going to search for the reference manual and other resources. I'd rather not unscrew the head yet!
Some good news again =)
I got to better control pulses (I need to really read more carefully datasheets), got acquisitions at 64Msps, really looking good, and got some (badly formed at the moment) images!
Acquisitions - going to specs at 64Msps. Thanks David =)
Pulser: getting 200ns wide 75V pulses (blue is the pulse with a piezo on, in yellow is the 'damping' control signal.
Getting some images from a "damaged" probe
More on the log!
That's moving forward! I'm getting some results with the following setup - using a piezo with a fixed distance, and a pulser at 25V.
Getting nice echoes (x-label in us)
The gain control works as well =)
and the FFT looks relatively clean!
I needed to replace some elements, some stuff is erratic, but hey, I've been able to set up all registers, run the analog part, and control the DAC gain. I (just) need to run the ADC now, the fpga still thinks s.he's not working ;)
Some pulse control works, and pulses too! With a 10x probe, on a 25V pulse
Next step.. digitalization. More on the log.
The clock had to be removed!
Investigation showed no connection through USB.. a ftdi issue. Powers were OK.. but still nothing.
So what? Clock!!
I unfortunately destroyed the 12MHz clock.. well that's it =) I'll be waiting for the new one from digikey.
The clock has to be rotated by 90°
More on the next session !
This has reached a couple of days ago =)
Looks good - ice40 and ram look good. The high-level pulser footprint seems reversed. The 3.3V is on, 5V level looks good, seems good!