Using exceptions in C++ embedded software

For several years I have been the lead developer of RepRapFirmware, which is firmware for 3D printers running ARM Cortex processors. Until recently I saw no compelling reason to use exceptions, so I compiled the firmware with gcc options -fno-exceptions -fno-rtti in order to keep the code small.

Dangerous failures

Sometimes, equipment that is supposed to be designed with safety in mind turns out to be unsafe. Here’s an example I came across a few years ago: a mains-powered smoke alarm installed in a top-floor flat:

Switching from Sage 50 to Xero Accounting Software

For once, here is a non-technical post from me. I’ll describe my experiences of changing from Sage 50 to Xero accounting software. In particular I’ll highlight a number of pitfalls that you might wish to be aware of prior to switching to Xero.

Improving the Robotdigg SCARA printer

In the first post in this series I described how I strengthened the bad T-frame of the printer and added adjustable levelling feet. These improvements made it possible to produce prints. The conversion to Duet electronics described in my second post improved print quality and provided faster print speed. However, the large amount of backlash in the distal arm joint drive remained, along with the lesser but still serious backlash in the proximal joint drive. If I was ever to get good prints from this printer, the backlash in both joints would need to be addressed.

Converting the Robotdigg SCARA printer to Duet electronics

In my previous post I described the Robotdigg SCARA Arm 3D printer in its original form. This post covers the conversion to Duet Ethernet electronics. It may seem odd to use top-of-the range electronics with budget mechanics, and I am not suggesting that it would make sense for other owners of this printer. In my case it made sense because I needed a test bed for testing and maintaining SCARA support in RepRapFirmware, the firmware that runs on the Duets.

Testing the Robotdigg SCARA Arm 3D printer

A colleague spotted this Robotdigg SCARA Arm 3D Printer which sells at just US$280 + shipping and import VAT. As I was working on SCARA printer support in RepRapFirmware, this seemed an ideal low-cost platform to test it on. So we bought one.

In this blog entry, I describe my experiences with this printer as it arrived and what I needed to do before I could try printing with it. A subsequent entry will describe the conversion to Duet Ethernet electronics.

Time to rebuild my large Kossel

It’s more than a year and a half since I published my large Kossel build blog entry. Since then I have upgraded it many times. Several people have built 3D printers based on this design, and some have asked for a more complete bill of materials. So I decided to create a page on this printer as it is now, including yet more upgrades.