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.
Once the servo controller code was feature complete I switched to looking at the hardware side of things and thinking about the next stage, the servo sequencing.
From a hardware point of view I had several things to work 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.
I decided to treat myself to an early christmas present and bought a 60W temperature controlled soldering station (a ZD-916 which I got from Maplin). All I can say is WOW. Suddenly I can solder neatly rather than making a smeary mess.
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.
Here is a schematic for a 24 channel version of the ATTiny2313 servo controller. You can expand the number of channels up to the full 64 by adding additional CD74HCT238Es where each additional MUX chip is connected to the next available pin on port b.
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 experimenting with the servo controller that I developed for the ATtiny2313 here and the demultiplexing chips that I mentioned here. The result is a 64 channel servo controller that seems to work pretty well. Right now I haven’t breadboarded all 64 channels, I have two of the CD74HCT238E chips connected to the ATtiny but I/O pins and he firmware would drive 8 of them if they were connected to give 64 channels.
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.
My progress has been slow over the past couple of weeks because a) I’ve been rather busy with other things and b) an order of components has gone missing in the post. The order contains some 4mhz crystals and therefore my server controller firmware testing has been on hold as I’d like to remove the potential clock instability as a potential cause of the controller jitters before continuing my debugging.
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…
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.
My package from Cool Components arrived this morning. My choice of prototyping equipment was quickly validated when I plugged together the Arduino and the Pololu servo controller board, plugged in the servos and servo power supply, connected the lot to the pc via a usb cable and had three servos twitching back and forth under the control of the Arduino is no time.
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.
First some basics: servo motors are what I’ll be using to provide movement for the robot. Each leg will consist of at least three servo motors (1 at the knee and two at the hip). As you’ll see from the wikipedia link above, servo motors are generally controlled by pulse width modulation.
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 most of my more interesting components have been purchased from Cool Components mainly because they’re UK based and they stocked stuff I was interested in. I found them via SparkFun which is a treasure trove of fun; unfortunately I can’t find UK distributors for much of the stuff they have available and at present I’m trying to avoid buying bits and pieces for this project from the US as the shipping is often more expensive than the order.
