Blogs

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 morning I tested the first version of my custom servo controller. It’s currently heavily based on the source for 16 channel servo controller that I’ve mentioned before. What I did was simply adjust that source for my target processor and the fact that I’m using it with a 4Mhz internal clock rather than the more standard “RS232 baud rate friendly” 3.

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 spending some time getting to know AVR Studio 4, especially the simulation and debugging functionality. It’s a very functional and very useful free development suite that can be downloaded from Atmel from here. As I mentioned a while back I have had a C compiler and development and programming tool chain set up for a while now but I hadn’t got around to working out how to debug the code.

Often when you’re writing a server or client application with The Server Framework you will find yourself needing to perform operations periodically or after a timeout. The Server Framework provides a light-weight timer queue that can be used to schedule timers and that uses minimal system resources so that there’s no problem with having multiple timers per connection; even on systems with 10,000 connections. The class used to manage per connection timers is the CThreadedCallbackTimerQueue class.

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.