This lab introduces some of the fundamental concepts involved with connecting devices to the ISA bus. A solderless ISA prototyping card will be used in conjunction with a number of ICs which you should come equipped with. Here is the shopping list which can be purchased from vendors on this vendors list. There are three main components to lab 1; the first is putting together the board (building a new device by wiring it up), the second is writing a kernel-space device driver for your parallel port device. The third is using a kernel space device driver to extend the operating system so that it makes use of the new device you have built.
See also http://wearcam.org/ece385/lecture6/index.htm (which is just a symbolic link to http://wearcam.org/ece385/lecture6/lab2.htm) for more info.
Generally we use
bare solderless breadboards signed out to each group
Larger - 64 kBytes
largest - 260 kBytes
| Pin No. | ISA Signal | Pin No. | ISA Signal | ------------------------------------------------------------------ | 1 | A0 | 2 | VCC | ------------------------------------------------------------------ | 3 | A1 | 4 | N/A | ------------------------------------------------------------------ | 5 | A2 | 6 | N/A | ------------------------------------------------------------------ | 7 | A5 | 8 | N/A | ------------------------------------------------------------------ | 9 | A6 | 10 | N/A | ------------------------------------------------------------------ | 11 | A7 | 12 | N/A | ------------------------------------------------------------------ | 13 | A8 | 14 | N/A | ------------------------------------------------------------------ | 15 | A9 | 16 | N/A | ------------------------------------------------------------------ | 17 | AEN | 18 | N/A | ------------------------------------------------------------------ | 19 | IOR | 20 | N/A | ------------------------------------------------------------------ | 21 | IOW | 22 | N/A | ------------------------------------------------------------------ | 23 | N/A | 24 | N/A | ------------------------------------------------------------------ | 25 | D0 | 26 | N/A | ------------------------------------------------------------------ | 27 | D1 | 28 | N/A | ------------------------------------------------------------------ | 29 | D2 | 30 | N/A | ------------------------------------------------------------------ | 31 | D3 | 32 | N/A | ------------------------------------------------------------------ | 33 | D4 | 34 | N/A | ------------------------------------------------------------------ | 35 | D5 | 36 | N/A | ------------------------------------------------------------------ | 37 | D6 | 38 | N/A | ------------------------------------------------------------------ | 39 | D7 | 40 | GND | ------------------------------------------------------------------
A satisfactory breadboard is available from Active Surplus (As of Thurs. September 28th, 2000, Chris who works at Active reports that there are 27 in stock), which has 5 distribution strips and 3 terminal strips.
Other kinds of breadboards available from various vendors are also suitable.
If you decide to be adventurous and do your own breadboard (rather
than, or in addition to, using the one we provide in the lab)
here is a useful diagram
available also in
PostScript
or
Proprietary
Data Format (PDF)
This diagram is layed out with the 40 pin header for our "ISA over IDE cable"
idea. The data/address registers, power, ground, etc are all
positioned on the sides of the diagram coresponding to their locations on
the card.
However, the ISA breadboard is much easier, if you want to get the lab done quickly.
It is preferable to have a breadboard wired up prior to class unless a student
is exceptionally skilled in art of wiring to wire it up in class.
This diagram:
(click to enlarge)
is the simplified diagram
that was shown in class,
and makes it easy to understand how the device will
work, once you wire it up.
The ISA bus has a relatively simple timing diagram which is worth examining in detail to understand the device you're building. The pinouts of the ICs used in the lab are available here.
The pitfalls in this section are as follows: don't get lost in the wires, and don't rush. It's better to be patient and build the board properly than hurry and make mistakes. Divide the labour appropriately; have one team member strip wires while the other wires, while the third checks and makes sure no mistakes are being made.
There are eight dip switches connected to the databus through a 74LS244 and eight LEDs connected from the data bus with a 74LS373. The eight dip switches provide something for you to read, and the eight LEDs provide something for you to write to. Thus the device allows you to test both reading from and writing to IO address 240.
At this point, you can modify your code from lab 0 to work with the ISA card. This provides an initial test of the wiring. Remember that you are no longer addressing addres 0x378.
Solderless breadboard with most components installed
Should take 60 minutes to assemble.
larger - 73 kBytes
largest - 299 kBytes
Closeup of above
larger - 114 kBytes
largest - 398 kBytes
Mostly completed board installed in wearcomp
larger - 114 kBytes
largest - 398 kBytes
The online O'Reilly Device Driver Book
Assuming you are using a 2.0, 2.2 or 2.4 series kernel, the device driver book should answer most of the questions you may have about writing device drivers. The next two parts of this lab are simply to write kernel-space device drivers to write (and possibly read) from the parallel port and the ISA card you have wired. If you followed the wiring diagrams above, the ISA card should be wired to read/write data from address 0x240. The parallel port is usually mapped to the address 0x378. Given all of this information, it should relatively easy to write the device drivers to complete this lab.
#define MODULE
#include < linux/module.h >
int init_module (void) /* Loads a module in the kernel */
{
printk("Hello kernel \\n");
return 0;
}
void cleanup_module(void) /* Removes module from kernel */
{
printk("GoodBye Kernel \\n");
}
If you type:
# rmmod hello.o
Didn't see the output???
Generally the output is not directed to the terminal. Rather, it is output to the system log. To see the system log, use the command dmesg, the last two lines of the output should be the output you were looking for.
However, to be fair i'll condense what you need here.
#include < linux/init.h >
#include < linux/module.h >
#include < linux/kernel.h >
static int hello_init(void)
{
printk(KERN_ALERT "Hello, world\n");
return 0;
}
static void hello_exit(void)
{
printk(KERN_ALERT "Goodbye, world\n");
}
module_init(hello_init);
module_exit(hello_exit);
Create a makefile in which the contents only has:
obj-m := module.o
Then type:
make -C /usr/src/linux SUBDIRS=$PWD modules
Note: in order for this command to work you must have you 2.6 kernel source symbolically linked to /usr/src/linux (you must also have your kernel source). You can still use insmod to load the module, however your kernel module will be called module.ko. You should be able to see this in your directory.
Also Note: insmod changed from version 2.4 The consequence of this is that you must apt-get install module-init-utils to acquire the necessary version of insmod.
Download pport.c. You will notice most of the code is filled in, with the exception of the bodies of module_read and module_write. It's up to you to fill out these functions. It should be reasonably straight-ahead with the help of the device drivers book. I will be posting a complete driver after the wednesday lab.
From reading the device drivers book and from previous lectures, you know that the kernel communicates to users through the filesystem. In particular, the module will communicate to the user through the /dev directory. We must create device nodes in this directory. To do this, first insmod your driver, then type:
cat /proc/devices
to get the major number assigned to the device
then type:
mknod /dev/pport0 c MY_MAJOR_NUMBER 0
mknod /dev/pport1 c MY_MAJOR_NUMBER 1
where MY_MAJOR_NUMBER is the major number you got assigned.
Now set the permissions for the device files:
chgrp sys /dev/pport0
chgrp sys /dev/pport1
chmod 666 /dev/pport0
chmod 666 /dev/pport1
You can try out you code by echoing to the /dev/pport files
echo -n -e "\377" > /dev/pport0
Now, you may open the device and communicate to it just as you would a regular file. For example, you may use fopen, fread, etc., to communicate with the device from any c program.
| Activity | Mark |
| Demonstrate a working ISA board from user space (with outb and inb). | |
| Demonstrate module_read working with your kernel-space device driver. | |
| Demonstrate module_write working with your kernel-space device driver. | |
| Demonstrate your working ISA driver on your newly wired ISA device. | |
| Modify the device driver to allow either inverting or non-inverting output by writing to either /dev/pport0 (inverting) or /dev/pport1 (non-inverting). | |
| Bonus points: implement a true kernelspace pushbroom that includes a pwm feature. This will be judged for general "coolness" and up to 2 bonus points may be awarded at the discretion of the TA. |
