Previously published This article was previously published on lhexapod.com as part of my journey of discovery into robotics and embedded assembly programming. A full index of these articles can be found here. After a little more debugging this morning I’m coming to the conclusion that I may have been a little harsh on the Arduino’s software serial port. More when I know more, but I think it’s more of a flow control issue with my data transmission from the PC.

Previously published This article was previously published on lhexapod.com as part of my journey of discovery into robotics and embedded assembly programming. A full index of these articles can be found here. Tonight I took a look at the ‘software serial’ support in the Arduino. I can’t say I’m that impressed… The Arduino has a built in hardware UART (a hardware serial port) which works as expected. It allows you to talk to external serial devices but there’s only one of it so if you want to have an external device talk to you via a serial port and then you want to talk to something else via another serial port then you’re out of luck.

Previously published This article was previously published on lhexapod.com as part of my journey of discovery into robotics and embedded assembly programming. A full index of these articles can be found here. I’ve been testing the new leg with one power supply for the servos and one for the electronics and all is working well. I expect that all would be working well if I were using a single power supply for both, as long as I was using the new one I soldered up and not the old one…

I’m in the process of upgrading another client to v6.0. These guys write multi-user game systems and have a fairly complex CLR hosting custom application server. Anyway, I was hoping that we’d have a few easy performance wins from the changes that have gone into v6.0 and these gaming guys are possibly even more hung up on performance than my banking and trading clients. The good news is that the changes in how we convert numbers to strings has drastically improved performance in their debug builds where they have lots of logging going on.

Previously published This article was previously published on lhexapod.com as part of my journey of discovery into robotics and embedded assembly programming. A full index of these articles can be found here. So far I’ve bought three AVR programming books. AVR: An Introductory Course, Programming and Customizing the AVR Microcontroller and Atmel AVR Microcontroller Primer: Programming and Interfacing (Synthesis Lectures on Digital Circuits and Systems). They are three quite different books and each has a distinct focus.

Previously published This article was previously published on lhexapod.com as part of my journey of discovery into robotics and embedded assembly programming. A full index of these articles can be found here. Having decided that the graduated servo positioning method was the way to go to allow for leg sensors to work correctly I started thinking about leg sensors. Here’s a new lower leg with three switches, one on the foot, one to the inside of the leg and one to the outside of the leg.

Previously published This article was previously published on lhexapod.com as part of my journey of discovery into robotics and embedded assembly programming. A full index of these articles can be found here. I adjusted my quick and dirty servo controller program to calculate the number of moves required for the servo that needed to move furthest and then spread the movement of the other servos across the same number of moves.

Previously published This article was previously published on lhexapod.com as part of my journey of discovery into robotics and embedded assembly programming. A full index of these articles can be found here. This week I managed to scrape together some time to play with some of the non prototype bits and pieces that I purchased for this project. First off was breadboarding a MAX232 chip so that I could talk via my PCs serial port to my ATtiny2313 microcontroller.

Previously published This article was previously published on lhexapod.com as part of my journey of discovery into robotics and embedded assembly programming. A full index of these articles can be found here. The prototype leg has some fairly major failings from a mechanical point of view. The only part that may eventually find its way into a weight bearing leg is the lower leg where the cut out around the knee servo provides ample support for the servo itself and also a suitable mounting point for the servo.

Herb Sutter has just published an interesting article over at DDJ on correctly using thread pools: Use Thread Pools Correctly: Keep Tasks Short and Nonblocking. It’s not rocket science and it doesn’t deal with platform issues but it’s a useful summary of why The Server Framework’s thread pools operate as they do. Note that on Windows you can use IO Completion Ports to manage the work queue into the thread pool and this can keep the number of threads that are scheduled to run at the optimum number so that the pool operates at the ‘correct load’ for most of the time even in the presence of blocking tasks.