Arduino On a Beadboard - Uploading Your Sketches

A few days ago I posted some intructions on how to use a standalone Atmega328 (or Atmega168) on a breadboard. This approach offer a good cost reduction for Arduino-based hobby projects by reusing the USB-to-TTL circuit between the projects. The cost saving can be close to $20, but there is a small tradeoff in convenience. Instead of the customary "plug in the USB cable and click 'Upload' ", we will need to hook-up a few wires; nothing too bad, though. Let's look at two different approaches: using FTDI adapter and an existing Arduino board.

Building Arduino on a Breadboard

Arduino on a Breadboard

In the previous post I showed threeways to reduce the cost of an embedded Arduino-based project: using one of the Arduino Pro variants, using a preloaded Atmega MCU and burning the bootloader yourself into  a blank Atmega MCU. For the first option, a “Pro” board with a Sparkfun's FTDI adapter all you need to do is to plug the board in (making sure that GND pin on the board matches that of the adapter) and you're good to go. The only drawback is the price tag of $20. The last option is the cheapest, but requires an AVR in-system programmed, and if you have an AVR ISP, chances are you don't need me to explain how to use it. The “Goldilocks” approach is to purchase the chips preloaded with Arduino bootloader. This approach provides a good balance between beginner-friendliness and cost. This is the option I will be using in my open source projects. In this post I will show you how to build a basic Arduino circuit on the breadboard.

Three Easy Ways to Reduce Arduino Project Cost

Arduino Pro Mini, Atmega 328 with Arduino Ominiloader Uno and a blank Atmega328P  

In response to the reader feedback I'm going to use Arduino for the DIY DRO Project and the stepper motor driven power feed. Arduino makes a great choice for beginners, in large part due to the standardized form factor and self-contained hardware. The flip side is that the boards cost between $35 and $70. “Wasting” a full-blown board for each little project gets expensive quickly. Every “mainstream” Arduino board comes with a USB-to-TTL adapter on-board that adds about $15-$20 to the board price. Having the adapter is convenient for prototyping, but in a “deeply embedded” projects this is a waste of money. Once you buy your first Arduino board or an “FTDI” adapter, the USB circuitry can be omitted. There are many ways to implement a minimalistic Arduino controller, but the most common ones are:

DIY Digital Readout Project Update - Display Boards Are Here

Ten brand-spanking-new LED display PCBs
for the DRO project

A week or so ago I finished laying out the LED display PCB for my DRO project. I built one unit some weeks ago using a prototyping board, but when a friend asked me to built one for her husband, I decided to bite the bullet and make a proper circuit board. This is by no means necessary, but wiring three MAX7221 on a prototyping board isn't my favorite pass time. Additionally, by using surface mount parts I was able to squeeze 24 digits (three rows of eight digits) and six tactile switches into a 5.75” x 3” board, whereas the initial prototype took 7”x5” prototype board for 18 digits (6x3) and no buttons.

Tramming Harbor Freight/Grizzly Mini Mill Column and Head

Yesterday I installed the "Large Table Assembly" and the "Air Spring Kit" from LittleMachineShop.com, so today was the time to tram the column and the head. I've seen some people tramming the column by attaching a dial indicator to the quill and adjusting the column unti the reading on both end of the table are equal. There is one huge flaw with this method: it doesn't tram the column, it trams the spindle. If you look carefully, the head is composed of two castings. The part that holds the bearings and the spindle is held by grou long bolts, and, you guessed it, is not always parallel to the dovetails. A tell-tale sign that your mill has this problem is when you jobber drill bits miss the spot that you started with the started drill bit. Essentially the head is perpendicular to the table but the column being at the angle offsets the head in the X axis as you move it up and down.

Alignment Problems with Large Table Assembly

While tramming the head on my mini mill (after installing the larger table), I came across an unexpected snag. I attached the dial test indicator to the spindle with a quill-style holder and prepared to zero it out on the right side of the table, but I noticed that swinging it across the table changed the reading. In fact, after zeroing the indicator on the front of the table, the probe didn't touch the surface on the back. Checking the column with a square showed a 1/8" runout over 6". Apparently something went terribly wrong, so I started troubleshooting. I took the column off the table, cleaned the surface, ran a file across the edge to make sure there were no burrs.

X2 Mini Mill Table and Air Spring Installation Progress

As I mentioned in the previous post, I bough a large table assembly and air spring upgrade kit. Yesterday I had a few hours to work on my mini mill, and this is a quick update on the progress. Installing the table is actually a trivial exercise: unbolt the three hex screws holding the column bracket to the table and bolt it to the new on. Since I'm installing the spring kit as well, so I ended up taking the whole mill apart.