We complete our clock module by adding a halt signal and test it with our address register. Now our (future) programs won’t have to run forever.

We add a reset circuit to our clock module that resets our address register to “0” on power-on and when a button is pressed.

We add three more 74LS163’s to our counter to make a 16-bit address register for our homebrew CPU project.

We connect our clock circuit to a 74LS163 synchronous binary counter and see how to count, reset and load values into the counter.

We add a potentiometer and a single-step button to our clock circuit.

In this video we create a clock circuit with a 555 timer in astable mode, and use it to blink a green LED.

This youtube video introduces the first step of a homebrew CPU project.

• Bank Python
• Excalidraw

This youtube tutorial covers interfacing with an LCD2004 20x4 LCD Character Display module with an HD44780 controller using only switches and simple components on a breadboard.

ckanext-scheming 2.1 now support Datasets with repeating subfields and repeating text fields. Repeating subfieds support custom snippets and validation just like regular fields.

This work is inspired by the excellent ckanext-composite extension and replaces ckanext-repeating repeating_text fields.

You must be using CKAN 2.8 or later and a custom IPackageController plugin to index datasets with repeating subfields.

• NumPy Illustrated: The Visual Guide to NumPy
• Half-Precision Floating-Point, Visualized
• Johnny•Decimal
• PostgreSQL index optimizations
• “A Mind is Born” 256-byte demo

Hello! Content from the old excess.org site will be migrated here over the next few months. Thank you for stopping by.

CKAN’s datastore_search now comes with format options and is up to 17x faster.

This article covers:

• new total row calculation
• new result generation
• new record formats

TL;DR:

1. Use CKAN 2.7 or later and resource views and other code that uses datastore_search is faster with no other changes required
2. Update your datastore_search client code to use one of the new records_format=csv and/or include_total=false options to make it much, much faster

I had the pleasure of co-hosting CKANCon last week and presented a short talk on ckanapi and ckanext-scheming.

For pyrf I needed to take data from a frequency plot, which could be any number of points, and present it as a spectrogram that fills the view size exactly. In the spectrogram I only care about the maximum values that appear in the range of frequencies represented by each pixel.

If I could just divide the number of source bins by an integer factor the solution would be simple:

return np.amax(data.reshape((-1, factor)), axis=1)

But I have to be able to handle any number of source bins and output that to any number of pixels.

Fortunately numpy is awesome.

I’ve been working on two new CKAN extensions that I’m really excited about. Since I helped build the custom metadata schema for open.canada.ca/ I’ve never been completely satisfied with the approach we took. These new extensions are the start of a proper solution to the compromises we made.

The new extensions are:

• ckanext-scheming data-driven custom schemas
• ckanext-fluent multilingual text fields

What does bar.foo do? - An exploration of Python assignment, objects, attributes and descriptors

This is a talk I gave March 27, 2014 at the Ottawa Python Authors Group meetup.

Follow along with the IPython notebook version if you would like to play with the code examples.

After working on PyRF this past year, I was asked to help edit to a paper written by ThinkRF’s Nikhil Adnani for AUTOTESTCON 2013: Wideband 20 GHz RF Digitizer and Python-based Open Application Framework for Test and Measurement.

This paper won the Walter E. Peterson award for Best Paper on Technology.