software

pyppm/software

This directory contains all the software required to use the PyPPM hardware.

Global compilation configuration information is stored in global.mk here, and each subdirectory sources that file before defining new make rules.

Core source code

A core set of functionality, located in core, has been written in the C language to interface to the PyPPM via the character device (usually /dev/ttyACM0) it creates on the host computer. All higher level code (including the Python module) wraps this core C code.

Note: Depending on the ownership of the /dev/ttyACM0 or /dev/cu.usbmodemPyPPM device file created by the operating system upon connection of the PyPPM to the host computer, you may have to run programs that talk to the PyPPM as root, e.g.: ./liveft would become sudo ./liveft, etc. This goes for any Python programs that use the pyppm module too.

Command-line utilities

The cli directory contains small command-line utilities that perform very small chunks of work. Each one either has a short conversation with the PyPPM hardware or does a small piece of data processing on acquired signals.

These cli utilities are meant mainly for the purposes of debugging. If you want to use the PyPPM for anything useful, the Python module is recommended.

A good test of the PyPPM and the cli utilities is to build them and run (with the PyPPM connected) a few short commands:

make
./ver
./rpp

These commands should connect to the PyPPM, read the firmware version and current pulse program in memory. If you've just flashed and connected the PyPPM, the pulse program dump should be all zeros.

Live acquisition view

The liveft directory contains source code for a small OpenGL application that continuously acquires short data streams from the PyPPM and displays an FFT'ed representation to the screen, with a bit of signal averaging. This program is really just for debugging the hardware analog signal chain.

To use liveft, just build it and run (with a PyPPM attached):

make && ./liveft

Signal-to-noise calculator

The napkin directory contains a small C program that may be used to perform a battery of calculations that predict experimental results (noise level, signal level, coil resistance, inductance, and quality, etc) from a few input values.

Example input values may be found in napkin/coil-2.0.txt. To compute the results, just build and run like so:

make && ./napkin < coil-2.0.txt

Free Induction Decay solvers

The solver directory holds a few GNU Octave scripts that may be used to solve for the resulting Free Induction Decay (FID) signal given a set of polarization properties. I wrote these scripts to illustrate the effect of long polarization turn-off times on FID intensity, a demonstration of the adiabatic theorem.

To run the solvers, just build:

make

Python modules

The Python modules in py are really where it's at. For more information on how to build, install and use the Python modules, read py/README.md.

Pulse programs

A library of known-good pulse programs has been started in the pulprogs directory in the form of a pure-Python module/package. More information on the available pulse programs and pulse program syntax is available in the pulprogs/README.md file.