The 3 Button Serial Mouse mini-HOWTO - Geoff Short (recommended reading TXT) 📗

The 3 Button Serial Mouse mini-HOWTO

 

Geoff Short, geoff@kipper.york.ac.uk

v1.33, 31 May 1998

How to get a 3 button serial mouse working properly under Linux.

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Table of Contents

1. Disclaimer 2. Introduction 3. Serial Ports 4. Switched Mice 5. Normal Mice 6. Switching a Mouse to 3Button Mode 7. Wheeled mice 8. Using gpm to Switch Mouse Modes 9. Using two mice 10. XF86Config and Xconfig file examples 11. Cables, extensions and adaptors 12. Miscellaneous Problems and Setups 13. Models Tested 14. Further Information 15. Mouse Tail

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1. Disclaimer

The following document is offered in good faith as comprising only

safe programming and procedures. No responsibility is accepted by the

author for any loss or damage caused in any way to any person or

equipment, as a direct or indirect consequence of following these

instructions.

2. Introduction

The most recent version of this document can always be found at

http://kipper.york.ac.uk/mouse.html

 

There is a Japanese translation at http://jf.gee.kyoto-u.ac.jp/JF/JF-ftp/euc/3Button-Mouse.euc; and a French one at

http://www.freenix.fr/linux/HOWTO/mini/3Button-Mouse.html. Other

translations may be available - check your local LDP mirrors.

 

Most X applications are written with the assumption that the user will

be working with a 3 button mouse. Serial mice are commonly used on

computers and are cheap to buy. Many of these mice have 3 buttons and

claim to use the Microsoft protocol, which in theory means they are

ideal for the X windows setup. (The record for the cheapest working 3

button mouse currently stands at $1.14!)

 

Most dual-protocol mice will work in two modes:

 

∑ 2-button Microsoft mode.

 

∑ 3-button MouseSystems mode.

 

This document leads you through the different steps needed to

configure your mouse in these two different modes, especially the

steps needed to use the more useful 3-button mode.

 

As distributions become easier to set up, some of the problems ought

to go away. For instance, RedHat have a mouseconfig program to set

things up for you. However, some versions of RH5.0 had a bug in

mouseconfig, so make sure you check for patches.

3. Serial Ports

The first thing to do is to make sure the software can find the mouse.

Work out which serial port your mouse is connected to - usually this

will be devttyS0 (COM1 under DOS) or devttyS1 (COM2). (ttyS0 is

usually the 9 pin socket, ttyS1 the 25 pin socket, but of course there

is no hard and fast rule about these things.) There are also an

equivalent number of devcua devices, which are almost the same as

the ttyS ones, but their use is now discouraged. For convenience make

a new link devmouse pointing at this port. For instance, for ttyS0:

 

ln -s devttyS0 devmouse

4. Switched Mice

Some mice, not usually the cheapest ones, have a switch on the bottom

marked `2/3’. Sometimes this may be `PC/MS’. In this case the `2’

setting is for 2 button Microsoft mode, and the `3’ for 3 button

MouseSystems mode. The `PC/MS’ switch is a bit more complicated. You

will probably find the `MS’ setting is for Microsoft, and the `PC’ is

for MouseSystems. You may find the `PC’ setting described as ps/2

mode, but it should do MouseSystems as well. If you have such a

mouse, you can switch the switch to `3’ or `PC’, put the MouseSystems

settings in your XConfigs (see below) and the mouse should work

perfectly in 3-button mode.

5. Normal Mice

If you don’t have any switches, and no instructions, then a little bit

of experimentation is needed. The first thing to try is to assume the

mouse maker is telling the truth, and the mouse is full Microsoft. Set

up your Xconfigs to expect a Microsoft mouse (see the Xconfig section)

and give it a try.

 

If the mouse didn’t work at all, then you don’t have a Microsoft

mouse, or there is some other problem. Try the other protocols in the

configs, the man page for the config file is the best place to start

looking. Also look in the Miscellaneous Problems section below.

 

What you will probably find is that when you run X, the mouse works

fine but only the outer two buttons do anything. You can of course

accept this, and emulate the third button (press both buttons at once

to click the middle one) like you do with a two button mouse. To do

this, change your Xconfig file as shown in the Xconfig example section

below. This may mean you have bought a 3 button mouse for no good

reason, and you are certainly no further forward. So, now you need to

look at your hardware.

6. Switching a Mouse to 3Button Mode

Even cheap mice can also work under the Mouse Systems protocol, with

all three buttons working. The trick is to get the mouse to think

it’s a Mouse Systems one, something you rarely see in your

instructions.

 

∑ Before you power up your computer, hold down the left mouse button

(and keep it held down until it has booted to be on the safe side).

 

When the mouse first gets power, if the left button is held down it

switches into Mouse Systems mode. A simple fact, but not always

publicised. Note that a soft reboot of your computer may not cut the

mouse power and therefore may not work. There are a number of other

ways of switching the mode, which may or may not work with your

particular mouse. Some of these are less drastic than rebooting your

computer, two are more so!

 

∑ If your computer is get-at-able you can unplug the mouse and plug

it back in with the button held down (although you shouldn’t

normally plug things in to a live computer, the RS232 spec says it

is OK).

 

∑ You may be able to reset the mouse by typing echo “*n” >

devmouse, which should have the same effect as unplugging it.

Hold the left button down for Mouse Systems mode, not for

Microsoft. You could put this in whatever script you use to start X

up.

 

∑ Bob Nichols (rnichols@interaccess.com) has written a small c

program to do the same thing, which may work if echo “*n” does not

(and vice versa). You can find a copy of his source code at

http://kipper.york.ac.uk/src/fix-mouse.c

 

∑ Someone has reported that the `ClearDTR’ line in the Xconfig is

enough to switch their mouse into Mouse Systems mode.

 

∑ If you are brave enough, open the mouse up (remember that this will

invalidate your warranty) and have a look inside. In some cases,

the mouse may have a switch inside, for some strange reason known

only to the manufacturer. More likely on the cheap mice is a jumper

which you can move. The switch or jumper may have the same effect

as a `MS/PC’ switch described in the “Switched Mice section”

above. You may find that the circuit board is designed for a

switch between 2 & 3 buttons, but it hasn’t been fitted. It will

look something like:

–––—

| o | o | o | SW1

–––—

1 2 3

 

Try linking pins 1-2 or 2-3, and see if it changes the behaviour of

the mouse. If it does, you can either fit a small switch, or solder

across the contacts for a quick and permanent solution.

 

∑ Another soldering solution which might be a last-resort for mice

which don’t understand MouseSystems at all, from Peter Benie

(pjb1008@chiark.chu.cam.ac.uk). If the middle button’s switch is

double-pole, connect one side of the switch to the left button’s

switch, and the other side to right button’s switch. If it’s not a

double pole switch then use diodes rather than wire. Now, the

middle button pushes the left and right buttons down together.

Select ChordMiddle in the XF86Config and you have a working middle

button.

 

∑ The ultimate recourse with the soldering iron was first described

to me by Brian Craft (bcboy@pyramid.bio.brandeis.edu). Two common

generic mouse chips are the 16 pin Z8350, and the 18 pin HM8350A.

On each of these chips, one pin controls the mode of the chip, as

follows.

 

Pin 3 Mode

–— –-

Open Default Microsoft. Mouse Systems if a button is held on power-up.

GND Always Mouse Systems.

Vdd Always Microsoft.

 

(Pins are numbered as follows:)

–-

pin1 -| / |-

pin2 -| |-

pin3 -| |-

-| |-

-| |-

-| |-

-| |-

pin8 -|–-|-

 

(This info comes courtesy of Hans-Christoph Wirth, and Juergen Exner,

who posted it to de.comp.os.linux.hardware) You can solder a link

between pin 3 and gnd, which will fix the mouse into MouseSystems

mode.

 

∑ Peter Fredriksson (peterf@lysator.liu.se) has tried the SYSGRATION

SYS2005 chip, and found that linking Pin 3 to Gnd forced Mouse

System mode.

 

∑ Uli Drescher (ud@digi.ruhr.de) confirms it works on an HN8348A

chip; Ben Ketcham (bketcham@anvilite.murkworks.net) confirms the

HM8348A (Pin 9 is Gnd).

 

∑ Urban Widmark (ubbe@ts.umu.se) says the same applies to the

EC3567A1 chip, where Pin 8 is ground. I’ve tried it as well and it

works fine.

 

∑ Timo T Metsala (metsala@cc.helsinki.fi) has found that on the

HT6510A chip pin 3 is mode select, pin 9 is Gnd. The same works

for the HT6513A chip. Holtek also make HT6513B and HT6513F chips -

on these, pin 8 is Gnd.

 

∑ Robert Romanowski (robin@cs.tu-berlin.de) says pin 3 - pin 8 (Gnd)

works on an EM83701BP chip too.

 

∑ Robert Kaiser (rkaiser@sysgo.de) confirms that pin 3 - Gnd works on

a EC3576A1 chip too.

 

∑ Sean Cross (secross@whidbey.com) found it was pin 2 - pin 7 (Gnd)

on a HM8370GP chip.

 

∑ Peter Fox (fox@roestock.demon.co.uk) used pin 3 - pin 8 on a

HM8348A chip.

 

∑ Jon Klein (jbklein@mindspring.com) found pin 3 - pin 9 did the

trick for a UA5212S chip.

 

∑ As an alternative to the above soldering methods, you can get the

mouse to hold it’s own button down when booting: this circuit from

Mathias Katzer.

–—

– R –––O–– + Supply

| –— | | C = 100nF capacitor

| | E | R = 100kOhm

| — / | T = BC557 transistor

| / O

| B | #V | T /

|–—|-# | / Left button switch of the mouse

| | # | O

| --/ |

– C |

– C ––O–––-> (to somewhere deep inside the mouse)

|

### Ground

 

The test mouse was a no-name model MUS2S - whether this works in other

mice depends on the circuit of the mouse; if the switch is connected

to ground and not to +Supply, an npn-transistor like the BC547 should

work; R and C have to be swapped then, too.

 

So there you have it, the choice is yours. Stick with the default

Microsoft two buttons, or work out how to switch the mode and set X up

to take advantage of this.

7. Wheeled mice

Mice with wheels have emerged in the last few years, starting with the

Microsoft Intellimouse and spreading to other manufacturers. The

wheel can be clicked like a button, or rolled up and down. Far and

away the best reference for information is

http://www.inria.fr/koala/colas/mouse-wheel-scroll/ which describes

how to get lots of X applications to recognise the scrolling action.

 

In general, you’ll need