Link

How to setup the board using only a usb cable

Beware! If you use this, you just need to have a usb cable plugged in.

Install jumpers and connectors as indicated in the figure below. Jumpers necessary are the white and the green ones.

Installation

Preparing Python

pip3 install pyftdi matplotlib numpy scipy

Installing iceprog to flash the fpga

iceprog is the software used to put the fpga on the flash storage on the board, which will be read by the fpga on boot. The easiest way is to :

sudo apt install fpga-icestorm

If this doesn’t work, then this may work:

sudo apt-get install libftdi-dev git gcc 
git clone https://github.com/cliffordwolf/icestorm.git
cd iceprog
make 
sudo make install

This will create and install the iceprog utility, used to flash the fpga program (bitstream).

FTDI rules.

Notes for Linux: Create a file /etc/udev/rules.d/53-lattice-ftdi.rules with the following line in it to allow uploading bit-streams as unprivileged user:

ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6014", MODE="0660", GROUP="plugdev", TAG+="uaccess"

This should solve usb access rules.

Board specific install files

Download the install pack or by

wget https://github.com/kelu124/un0rick/raw/master/usb/install_pack.zip

Connect the usb cable

Check that the FTDI device is well created by typing:

dmesg

Programming it

Unzip it, inside, there’s the bin to program the fpga :

iceprog usb.bin

Running python

Test

There is a test bench for the python lib matching the usb firmware, from the brodie package. Installation is as follows.

mkdir experiment
cd experiment
wget https://raw.githubusercontent.com/kelu124/echomods/master/matty/20201026a/brodie.zip
iceprog un0rick_ms3_icestorm.bin
cd fpga_ctrl/
python3 test.py

which will run a series of acqs and produce a series of images from this acquisition.

Using the python lib

In python

In essence, installing the module pip3 install un0usb before.

	import un0usb as USB # neeeds `pip3 install un0usb` before
	fpga = USB.FpgaControl('ftdi://ftdi:2232:/', spi_freq=8E6) # init FTDI device 
	fpga.reload() # reload configuration
	fpga.reset() # reset fpga

	file = fpga.stdNDTacq() # Running a standard NDT acquisition
	plot = USB.FView() # Opens a viewing object
	data = plot.readfile(file) # plots it

Result

The full log is here.

Going in deeper details

Imports

In the fpga_ctrl folder, you’ll need the csr_map, ftdi_dev.py, and fpga_ctrl files, to import the lib:

from fpga_ctrl import FpgaControl

I encourage the reader to go inside this libs, which are already documented.

Create the device

then connect to the FPGA

# init FTDI device
fpga = FpgaControl('ftdi://ftdi:2232:/', spi_freq=8E6)
# reload configuration (optional step - just to fill BRAM (DACGAIN registers) with initial values)
fpga.reload()
# reset fpga
fpga.reset()

Pulser control

To control the waveform, one would set the fpga.csr.ponw, fpga.csr.interw and fpga.csr.poffw, that are respectively integers for setting the width (timing) of the pulse, width of a relaxation period before damping, and then duration of damping. Unit are (1/128us).

The fpga.csr.initdel register is the delay between the beginning of the acquisiton and the pulse.

fpga.csr.initdel = InitDel
fpga.csr.ponw = PONWidth
fpga.csr.interw = INTERWidth
fpga.csr.poffw = PDAMP

Below is plotted amplitude of an echo as a function of the fpga.csr.ponw for a 4MHz transducer. One sees that a setting at 16 provides most

(See full experiment here).

Gain and acquisitions

And do acquisitions with acq_res = fpga.do_acquisition(acq_lines=32, gain=gain, double_rate=True) which will return an array of acq_lines acquisitions, of length 256us at 64Msps. double_rate=True provides a half clock offset to odd lines, so that one can interleave two subsequent acquisition to have, in a fixed setting, a 128Msps acquisition.

The gain setting is an array of integers, of length 32, that can range from 0 to 1023, controlling gain for each of the 32 8us-segment of acquisition within the 256us line.

Other registers

  • fpga.csr.led3 = 0 sets LED3 off. led1, led2, led3 are possible, can be set to 0 or 1.
  • fpga.csr.topturnX reads input 1 to 3 on the input header.
  • fpga.csr.jumperX reads jumper 1 to 3 close to the programming jumper.
  • fpga.csr.outXice writes/reads output 1 to 3.
  • fpga.csr.nblines = acq_lines - 1 is the register controlling the number of lines acquired.
  • fpga.csr.dacout reads the DAC/TGC/VGA level outside of acquisitions.
  • fpga.csr.acqstart = 1 to start the acquisition
  • fpga.csr.drmode = int(double_rate) triggers the interleaving mode.
  • fpga.csr.acqstart = 1 to start the acquisition
  • fpga.csr.acqdone is equal to 0 during acquisitions.
  • fpga.csr.author reads the ID of the author of the binary.
    • 1 : kelu124
  • fpga.csr.version reads the ID of the author’s binary.
    • 1 The current binary version

Don’t hesitate to improve the gateware and push more here.

Example of acquisitions

Raw signal, with DAC

The signal is in blue, the gain levels are in green. Here there are 32 visible steps, of 8us each.

Detail of an echo

Interleaved acquisiton mode = ON

Doublign acquisition speed (yellow and red dots below)