Who doesn’t want to use a programming language that is designed to be reliable, straightforward to learn and also happens to be certified for everything from avionics to rockets and ICBMs? Despite Ada’s strong roots and impressive legacy, it has the reputation among the average hobbyist of being ‘complicated’ and ‘obscure’, yet this couldn’t be further from the truth, as previously explained. In fact, anyone who has some or even no programming experience can learn Ada, as the very premise of Ada is that it removes complexity and ambiguity from programming.
In this first part of a series, we will be looking at getting up and running with a basic desktop development environment on Windows and Linux, and run through some Ada code that gets one familiarized with the syntax and basic principles of the Ada syntax. As for the used Ada version, we will be targeting Ada 2012, as the newer Ada 2022 standard was only just approved in 2023 and doesn’t change anything significant for our purposes.
Ordering a PCB with mistakes sucks. We should help each other avoid such mistakes – especially newcomers. One of the best ways to avoid these mistakes, especially if it’s your first one, is to get a few other people to look at it. You deserve to get a PCB that is as functional and as helpful as humanly possible, so that you can be happy with your project, and feel ever so slightly more confident in yourself in whatever you shall set out to do next.
At the end of last year, I put out a call for design review submissions, and we’ve received enough projects to make me feel overwhelmed for a bit. A design review has always felt like a personal thing, and here we are doing them in public. But in that sense, we hope that everyone can learn from them, and we hope to push forward a healthy review culture.
What’s more, these articles won’t just be design review. Every project I’m highlighting is worthy of a Hackaday feature just on its own, so tune in and learn more about them!
Today’s Contestant
For this example, I will be walking through a review I’ve already given someone with a pretty cool board, for a pretty cool project I’ve already shown you. Remember the Sony Vaio remake project? A fair bit of people have reached out to me afterwards, and one of them, [Exentio] also had the same Sony Vaio rebuild idea in mind. We started chatting, and he decided to tackle one of the project’s milestones, and perhaps the most crucial one – adapting the LCD.
Last time, we looked at some powerful trigger modes found on many modern scopes, including the Rigol DHO900 series we used as an example. Those triggers were mostly digital or, at least, threshold-based. This time, we’ll look at some more advanced analog triggers as well as a powerful digital trigger that can catch setup and hold violations. You can find the Raspberry Pi code to create the test waveforms online.
In addition to software, you’ll need to add some simple components to generate the analog waveform. In particular, pin 21 of the Pi connects to 2uF capacitor through a 10K resistor. The other side of the capacitor connects to ground. In addition, pin 22 connects directly to the capacitor, bypassing the 10K resistor. This allows us to discharge the capacitor quickly. The exact values are not especially important.
Runt Triggers
A runt pulse is one that doesn’t have the same voltage magnitude as surrounding pulses. Sometimes, this is due to a bus contention, for example. Imagine if you have some square waves that go from 0 to 5V. But, every so often, one pulse doesn’t make it to 5V. Instead, it stops at 3V.
Last time, I talked about racing the beam, a type of graphics used when memory was scarce. Now it’s time to step into the future with more memory and talk about what modern 2D games still do to this day: rasterization.
Just in time Memory
Continuing the trend set by racing the beam, rasterized graphics are also on a grid, just a much tinier one. Though not unique to rasterized, the “frame buffer” is the logical conclusion of bitmap mode fidelity: enough memory is allocated so that every pixel can have its own color. What’s different about a frame buffer is that everything is drawn before it is shown and, crucially, this doesn’t have to happen in the same order as the pixels are displayed. Rasterization draws entire shapes — triangles, lines and rectangles — into the frame buffer and the screen is typically updated all at once. Continue reading “Game Graphics: Rasterization”→
Will Rogers once said that veterinarians are the best doctors because their patients can’t tell them where it hurts. I’ve often thought that electronic people have a similar problem. In many cases, what’s wrong with our circuits isn’t visible. Sure, you can visually identify a backward diode, a bad solder joint, or a blown fuse. But you can’t look at a battery and see that it is dead or that a clock signal isn’t reaching some voltage. There are lots of ways to look at what’s really going on, but there is no substitute for a scope. It used to be hard for the average person to own a scope, but these days, it doesn’t require much. If you aren’t shopping for the best tech or you are willing to use it with a PC, oscilloscopes are quite affordable. If you spend even a little, you can now get scopes that are surprisingly capable with features undreamed of in years past. For example, many modern scopes have a dizzying array of triggering options. Do you need them? What do they do? Let’s find out.
I’ll be using a relatively new Rigol DHO924S, but none of the triggering modes are unique to that instrument. Sometimes, they have different names, and, of course, their setup might look different than my pictures, but you should be able to figure it out.
What is Triggering?
In simple terms, an oscilloscope plots time across the X-axis and voltage vertically on the Y-axis. So you can look at two peaks, for example, and measure the distance between them to understand how far apart they are in time. If the signal you are measuring happens repeatedly — like a square or sine wave, for example — it hardly matters which set of peaks you look at. After all, they are all the same for practical purposes.
Pretty square waves all in a row. Channel 2 is 180 degrees out of phase (inverted). But is that all there is?
The problem occurs when you want to see something relative to a particular event. Basic scopes often have level triggering. They “start” when the input voltage goes above or below a certain value. Suppose you are looking at a square wave that goes from 0 V to 5 V. You could trigger at about 2.5 V, and the scope will never start in the middle of a cycle.
Digital scopes tend to capture data before and after the trigger, so the center of the screen will be right on an edge, and you’ll be able to see the square waves on either side. The picture shows two square waves on the screen with the trigger point marked with a T in the top center of the display. You can see the level in the top bar and also marked with a T on the right side of the screen.
What happens if there are no pulses on the trigger source channel? That depends. If you are in auto mode, the scope will eventually get impatient and trigger at random. This lets you see what’s going on, but there’s no reference. If you are in normal mode, though, the scope will either show nothing or show the last thing it displayed. Either way, the green text near the top left corner will read WAIT until the trigger event occurs. Then it will say T’D.
Last time, I assembled a Python object representing a Rigol oscilloscope. Manipulating the object communicates with the scope over the network. But my original goal was to build a little GUI window to sit next to the scope’s web interface. Had I stuck with C++ or even C, I would probably have just defaulted to Qt or maybe FLTK. I’ve used WxWidgets, too, and other than how many “extra” things you want, these are all easy enough to use. However, I had written the code in Python, so I had to make a choice.
Granted, many of these toolkits have Python bindings — PyQt, PySide, and wxPython come to mind. However, the defacto GUI framework for Python is Tkinter, a wrapper around Tk that is relatively simple to use. So, I elected to go with that. I did consider PySimpleGUI, which is, as the name implies, simple. It is attractive because it wraps tkinter, Qt, WxPython, or Remi (another toolkit), so you don’t have to pick one immediately. However, I decided to stay conservative and stuck with Tkinter. PySimpleGUI does have a very sophisticated GUI designer, though.
About Tkinter
The Tkinter toolkit lets you create widgets (like buttons, for example) and give them a parent, such as a window or a frame. There is a top-level window that you’ll probably start with. Once you create a widget, you make it appear in the parent widget using one of three layout methods:
Absolute or relative coordinates in the container
“Pack” to the top, bottom, left, or right of the container
Row and column coordinates, treating the container like a grid
The main window is available from the Tk() method:
That’s about the simplest example. Make a button and close the program when you push it. The mainloop call handles the event loop common in GUI programs.
It used to be only high-end test equipment that had some sort of remote control port. These days, though, they are quite common. Historically, test gear used IEEE-488 (also known as GPIB or, from the originator, HPIB). But today, your device will likely talk over a USB port, a serial port, or a LAN connection. You’d think that every instrument had unique quirks, and controlling it would be nothing like controlling another piece of gear, especially one from another company. That would be half right. Each vendor and even model indeed has its unique command language. There has been a significant effort to standardize some aspects of test instrument control, and you can quickly write code to control things on any platform using many different programming languages. In a few posts, I will show you just how easy it can be.
The key is to use VISA. This protocol is defined by the IVI Foundation that lets you talk to instruments regardless of how they communicate. You do have to build an address that tells the VISA library how to find your device. For example: “TCPIP::192.168.1.92::INSTR.” But once you have that, it is easy to talk to any instrument anywhere.
I say that thinking it is a problem is half right because talking to the box is one task of the two you need to complete. The other is what to say to the box and what it will say back to you. There are a few standards in this area, but this is where you get into problems. Continue reading “How To Talk To Your Scope”→
Who doesn’t want to use a programming language that is designed to be reliable, straightforward to learn and also happens to be certified for everything from avionics to rockets and ICBMs? Despite Ada’s strong roots and impressive legacy, it has the reputation among the average hobbyist of being ‘complicated’ and ‘obscure’, yet this couldn’t be further from the truth, as previously explained. In fact, anyone who has some or even no programming experience can learn Ada, as the very premise of Ada is that it removes complexity and ambiguity from programming.
