August 2009
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A timer driven PWM servo controller - part 4
The time has finally come to put all of the code from the last three parts of this article together to form a complete serial configured, 64 channel, PWM servo controller for the ATTiny2313 and several CD74HCT238Es. Here’s a recap of … -
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ATTiny2313 24 channel servo controller schematic
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 … -
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Tweaking the servo controller
The 64 channel serial servo controller that I’ve been developing works pretty well for me but most of my development and testing was done in the AVR studio simulator. Once I actually started working with my hardware again I noticed a … -
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What's next?
I now have an easy to extend PWM servo controller and the next job on my list of things to do is extend it so that it supports the functionality that I feel I need for correct control of my hexapod’s legs. As I mentioned here, … -
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Extending the servo controller
To be able to implement the new commands for the servo controller I need to adjust the data that we use to control the servos. Right now we have a single byte per servo and that byte contains a value between 0 and 254 which represents the … -
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All the problems of multi-threading without the threads
One of the problems of moving from the simple three byte SSC style control system to a system where we can do clever things with multiple servos at once is that the data required to do these clever things is bigger than the data required to … -
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Asynchronous serial responses
Part of the new functionality that I’m developing for the serial servo controller for my hexapod robot is for the servo controller to take its time in moving a servo from where it is at the moment to where I want it to be. The idea … -
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Registers, stack usage and timing
So far the servo controller development has been reasonably straight forward; once various design issues were considered and once I’d got my head around building the hardware and learning AVR assembly language. However I expect that … -
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And then switch to the ATMega168...
The new functionality in my servo control takes more memory to implement due to the more complex state that we need to maintain for each servo. The simple controller could support up to 64 PWM channels on the ATTiny2313, the more advanced … -
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Prototype fabrication
As I mentioned back in April after I’d put together my first prototype leg, “the prototype leg has some fairly major failings from a mechanical point of view”. Ideally the real legs will be designed and cut from sheet …
