Sheldon robot: exploring the hall effect sensors

The 9V motors on the T300 robot vehicle are each fitted with two hall effect sensors that act as encoders. I figured I’d take a closer look. The two sensors are positioned to read a magnet attached to the rear of the motor’s shaft. They are quite close together so that, as the magnet rotates, one will be triggered very… Read more »

Sheldon robot: motor encoder connections

The 9V geared motors fitted to the T300 tank, which forms the base vehicle for my Sheldon robot project, come fitted with encoders. I’m not sure I need these, but they might be useful to have. But first I had to do a little simple reverse engineering to work out how to connect them. Each motor has a six-pin connector,… Read more »

Sheldon – the soft robot

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A comment over on Reddit made me realise that I haven’t yet mentioned a key characteristic of my Sheldon robot project – inaccuracy. I mean, I could* built a robot with incredible precision that would be able to locate and move itself to tolerances of fractions of a millimetre. Think of those amazing pick-and-place robots that populate circuit boards with hundreds… Read more »

Sheldon robot: controlling the motors

Many beginners’ guides to electronics teach you how to build motor controllers using mosfets, H-bridge circuits and all that good stuff. And maybe I’ll get around to doing that one day. But to get this robot project up and rolling, I decided to go for an off-the-shelf motor controller. I’ve used many before, including Arduino shields from Adafruit and Snootlab…. Read more »

Sheldon robot: architecture

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Right from the beginning I knew that the Sheldon robot would have a multi-processor architecture. This appeals to me the same way object-oriented programming appeals – you can create a modular system in which each part does a specific task and can be treated like a black box. The structure will be hierarchical. At the top – what I’m going… Read more »

Sheldon robot: the base vehicle

One of the things that spurred my current interest in electronics was a resurgence of my fascination with robots. And so, here we go with another project – a robot base vehicle that I can use for experimenting with sensors and algorithms. (Technically, this is not a new project – it’s a new start to a years-old project, but anyhoo…)… Read more »

First BBC Basic program: mission creep

It’s always the same. “I’ll just hack out this quick program,” you think. And you get it to the point where it works and does the job you intended it to do. But then: “Maybe it would be nice if it also did this…” And even when you’ve added all the functionality the program will bear, and your wife is… Read more »

A home for my BBC Micro DataCentre

In the last post, I mentioned how I’m using a RetroClinic DataCentre to make it easy to transfer files between the BeebEm emulator on my PC and my real BBC Master 128. A USB memory stick plugged into the DataCentre becomes my main disk drive (*DRIVE 5) for program files. It also holds floppy disk images (single-sided .SSD and double-sided… Read more »

Programming the BBC Micro with ease

No, this isn’t going to be a tutorial on BBC Basic. Nor am I about to offer programming tips and tricks. This is about being comfortable while hacking. In the last post I wrote about recreating the first serious program I ever wrote on the BBC Micro. And I mentioned that I’d written the code using the BeebEm emulator running on… Read more »

First time with BBC Basic

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So what was your first program? You know, the first one that meant anything. My guess is that when you unwrapped your first home computer (mine was a Sinclair Spectrum 48K) the lines of code you typed were little more than snippets – changing some colours on the display, perhaps, or making rude words scroll endlessly down the screen. You… Read more »

Feels like 2001: a fresh Windows XP install

Ah, there’s nothing quite like the feel of a fresh, crisp OS install. It’s just that the OS I’ve just installed is Windows XP. Now that makes no sense… Or does it? As I’m now playing with my BBC Master again, I felt the need for a Windows machine to have alongside it. There’s a bunch of utilities that run… Read more »

Flowchart your way to success

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Does anyone still use flowcharts for programming? What with today’s complex development frameworks it seems unlikely that anyone’s stopping to draw diagrams on paper. But maybe if they did we’d have fewer security vulnerabilities – just sayin’. My addiction to computers, in the early 1980s, was driven in part by ‘30 Hour Basic‘, an introduction not just to the language… Read more »

ESP8266 IoT room thermometer – part 3

The best projects are the ones you finish. And as projects go, this IoT room thermometer – and, for good measure, clock – was one of the easier ones. To recap, I wanted a thermometer in my office to measure the temperature and compare that with how I’m doing, at any given time, in terms of hand pain. I have… Read more »

SMD soldering coda: KiCad, PCBs and pad sizes

In many ways this is Part 5 of my four-part series on SMD soldering because it addresses problems I had with reflow soldering and TSSOP ICs. I used two TSSOP chips – the TXB0104 and TXB0108 level shifters. Both have pin sizes of 0.3mm and a pin pitch – the distance from the centre of one pin to the centre… Read more »