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a driver to expose functions from the teensy board as character devices
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CS 572 Class Project, Fall 2010 at Portland State University ============================================================ The objective is to develop a general purpose driver for the teensy micro-controller that exposes a series of abstract character devices in userland. These devices will control various aspects of the teensy for a variety of purposes. The idea is that a simple set of ioctls, along with reads and writes can provide general purpose functionality without fiddly access to the teensy directly. Important Warning ================= This project involves connecting a general purpose microcontroller directly to your usb controllers and then doing arbitrary things with them. If you don't know what you're doing, you could easily fry your usb controllers on you spiffy new laptop. You could also let the magic smoke out of your fun new teensy. Proceed at your own risk. You have been warned! Building ======== There are included Makefiles for building everything in this project. But, note that this is written against the 2.6.24 linux kernel and may not build cleanly against just any ol' kernel. --- Kernel module: Building the kernel module requires the appropriate kernel headers be installed. If you are running a 2.6.24 kernel, then the makefile should just find the headers (assuming they are installed). If you are building while running a different kernel, it makefile looks in your home directory for src/linux-2.6.24. It's up to you to fix that however is appropriate. --- Teensy code: The actual code to run on the teensy requires the following packages (using Debian names because that what we build on): gcc-avr avr-libc That should get you a reasonable build-environment to compile for the teensy. Using ===== To use the code, you have to first insert the kernel module in the usual way: insmod teensy_mono.ko And then plug in the device. The module will see the teensy and configure itself to expose some adc converters and two motor controllers. These are character devices that interact as follows: /dev/adc: a read() on these devices will return one 8 bit reading from the appropriate adc device on the teensy. /dev/mc: using ioctl()'s, you can control a dc motor connected to the teensy. See teensy_mc.h for details of available ioctls and see the diagrams for how to hook up a couple of motors to the pwms.