Ultimate Amiga PS/2 Wheel Mouse Controller

How to build PS/2 Wheel Mouse Controller

For beginning: from version 1.4, there is new version of hardware - but you can still use your old hardware because of two new firmware versions. Detailed description of each of them with schemes and links to firmwares you can read here.

Part list

You will need at least following for building this controller:

PIC16F627 or PIC16F628
DB-9 female connector - to Amiga side
MiniDIN-6 female connector - to mouse side
Some wires (or PCB)

If you don't have PIC16F62x, or you want to modify existing PIC16F84-based controller and anyway don't want to use 2-wheel mice or joystick simulation in future, you can still use

PIC16F84 (PIC16F84A, or even old PIC16C84)
4MHz crystal or ceramic resonator

instead of PIC16F62x. Current and all next versions of firmware anyway will support both PICs.

If you want to reduce cost of controller by approx. 2 USD, you can replace flash PIC by OTP (One-Time-Programmable) PIC. It may be one of following PICs: PIC16C554, PIC16C558, PIC16C620, PIC16C621, PIC16C622 and some others. Them are cheaper, but you can't update firmware - you will need to replace PIC for that. Additionally, there is no OTP PIC programmers on Amiga now (June 2001), and you will need to program it elsewhere.

Optionally, you may use following parts:

18pin socket for PIC - highly recommended for PIC & firmware upgrades!
(but you can install PIC16F627 even now and use in-circuit programming)
Two 20pF capacitors - them are required if resonator doesn't start or start at wrong frequency (and recommended - but in most cases not needed).
0.1uF blocking capacitor in parallel with mouse power - recommended too, but not required.
2k resistor - recommended for 4-button version.
Second DB-9 female connector, if you want to use wheel and additional buttons.
DB-9 connector cases (boxes)

PIC programming

You can program PIC on existing programmer, or build my simple devpic package.

In case of programming PIC on existing programmer, you must select following options:

OSC = HS

WDT = ON

That was parameters for all usable PICs including OTP, but not for PIC16F62x. If you will use PIC16F627 or PIC16F628, you must select following options:

OSC = INTRC without CLKOUT

WDT = ON

LVP = OFF

MCLRE = OFF (digital I/O or something similar)

Other options don't play any role.
In case of building devpic, download it from Aminet and build it. Devpic is a simple device on parallel port, based on one «glue logic» chip and some resistors & diodes. One of useful devpic features is an in-circuit programming - you can reprogram PIC for future versions even in working device (but for some reason you must disconnect it from joyport during programming).

Devpic will program PIC16F84(A) by following command:
picprog ps2m.hex force=16382
For programming PIC16F627 or PIC16F628 you will use command:
picprog ps2m.hex force=16212 sf=2

«FORCE» keyword describes configuration word, that contains configuration bits like OSC and WDT (and also LVP & MCLRE for PIC16F62x). Normally it can be «CW» keyword, but «FORCE» does also code deprotection if PIC was protected. Don't use that keywords when you update firmware - PIC remembers last configword. «SF» is «SmartFlash» mode of picprog, that speed ups new PIC's programming up to 5 times in comparison with PIC16F84.
OSC is an OSCillator mode (PIC can handle resonators or RC circuit), and WDT is WatchDog Timer - it is an internal PIC circuit, that automatically resets it if it hangs. WDT is required for PS/2 controller - it is used in algorithm not only for exception cases, but even for mouse waiting. LVP is a Low Voltage Programming - in this mode programmer doesn't need 12v, but we lose RB4 PIC pin. MCLRE - purpose of MCLR pin, in our case it works as general input pin (maybe useful in future versions). If you don't want to understand all this details - simply use string as described above.
If you had problems with PIC programming - forget your old devpic archive, and try new devpic release (now 1.6) with v3 hardware, it is more stable than v2.

Building of device

Finally select hardware version, and build it by schematic diagrams. Personally I don't use PCB, and I assemble it directly in DB-9 connector case (see photos on front page of manual). But if you want to do PCB - there is a reference PCB design, done by Marc SAVART [sil51#ifrance.com]. It is designed for use on A4000T (also you can see photos archive of ready device). I can't give any warranty for this PCB design, but now I manually check every version for wrong connections :)

Debugging

If assembled device doesn't work - there is a list of probable errors:

Incompatibility with your mouse - try another one
Overloading of 4-button version (by optical mouse for example)
Error in connections
Erroneous PIC programming or incorrect configuration word
Bad resonator (try to install 20pF capacitors)

If you have oscilloscope - see signal at OSC pins (not for PIC16F62x). Schematic diagram is already tested and doesn't contain bugs. There are tens of people that assembled and use it now.

Modifications

Probably it is a most interesting part of this manual :-) Because of open source you can modify source code for your needs. This source may be recompiled by picasm assembler (you can find it in devpic package). There is macros.i file, contains my favorite macro operators - it must be in current directory for picasm with source file. Usage of picasm is very simple:

picasm ps2m

Both firmware versions may be generated from one source because of conditional asseymbly usage. POWER variable (see line POWER equ...) defines it - 0 value is a 5-button version, and 1 value is a 4-button version. SPEED variable allows you to use different resonators, than 4MHz (see comment).

Some comments about several program parts destination:

Label Description

int Interrupt handler - it is called every mouse clock (11 times per byte) and eats approximately a half of 4MHz PIC speed. After byte receiving, this routine stores received byte in recvdt and sets flag fbyte. These bytes are stored in packet buffer in «main loop».

start
start_a Init code. Some details about mouse detection:

At first, there is Genius init sequence: 0xE8 0x03 0xE6 0xE6 0xE6 0xE9. After 0xE9 command mouse sends status bytes, or Genius NetScroll magic sequence 0x00 0x33 0x55. In last case (it means that it is Genius NetScroll with 5 buttons), controller uses Genius mode and skips next init sequences.
At second, there is Microsoft init sequence: 0xF3 0xC8 0xF3 0x64 0xF3 0x50. After this, controller reads mouse ID (0xF2) and checks it for equivalence with 3. If it is true - mouse is in Intellimouse mode now (wheel + 3 buttons).
At third, there is new Microsoft init sequence: 0xF3 0xC8 0xF3 0xC8 0xF3 0x50. After this, controller reads mouse ID again and checks it for equivalence with 4. If it is true - mouse is in Intellimouse Explorer mode now (wheel + 5 buttons). If mouse ID still is 3 - it means that it is only Intellimouse - not Explorer.

m_check It is a code, that will be executed after 2 seconds of mouse «silence». It reads mouse status and sees stream mode flag. If stream mode is disabled - this means that mouse was reconnected. In this case controller will reset it.

p_init Here is setting of initial values of «virtual sync serial port». It is used mainly for «re-sync» if sync was lost due to electric surge/noise (bit(s) was lost or unnecessary bit(s) was added).
Additionally, this routine contains check for «alien» signal on LMB pin (for example - second joystick «fire») and disable controller.

schk This routine receives bytes in packet buffer (byte1-byte4). After this it sets fpkt1 flag.

pchk1 This routine will be called after receiving of full packet. Because of controller is all time in «main loop» simulates mouse movement, packet processing is done by several parts. It is a first part - processing of horisontal movement. After processing this routine sets flag for next routine (fpkt2), and without own flag (fpkt1) it will not be processed again up to next packet receiving.
Processing of movement contains calculating of mouse speed - movement will be done with this speed.

pchk2 This routine is like previous, and it processes vertical movement.

pchk3 This routine processes all mouse buttons (at first - standard three buttons), and then it processes additional buttons and wheel (only if these were detected).

tchk It is a timer support. Controller updates mouse signals only approx. 6000 times per second. If next 1/6000 of second doesn't approach yet, controller will return to checking of next byte.

mchk It is a mouse checking - as described above.

xchk
ychk It is realtime update of movement counters with needed speed.

zchk Wheel counter update.

xyout Movement counters and fourth button are simultaneously updated here.

cpoff This subroutine enables controller, if it is disabled. Additionally it sets counters in default state.

testms Check for Microsoft protocol(s). Both protocols are checked in one subroutine because of similarity (one byte difference).

send Sending byte to mouse. Because of rare nature of this action, it is not done by interrupt engine (that also unloads interrupt routine from rare instructions).

bwait It is a waiting for byte from mouse. Actually a byte receiving subroutine.

delayms
delayus Delays by milliseconds and fourt microseconds (in W).

OSC	=	INTRC without CLKOUT
WDT	=	ON
LVP	=	OFF
MCLRE	=	OFF (digital I/O or something similar)

Label	Description
int	Interrupt handler - it is called every mouse clock (11 times per byte) and eats approximately a half of 4MHz PIC speed. After byte receiving, this routine stores received byte in recvdt and sets flag fbyte. These bytes are stored in packet buffer in «main loop».
start start_a	Init code. Some details about mouse detection: At first, there is Genius init sequence: 0xE8 0x03 0xE6 0xE6 0xE6 0xE9. After 0xE9 command mouse sends status bytes, or Genius NetScroll magic sequence 0x00 0x33 0x55. In last case (it means that it is Genius NetScroll with 5 buttons), controller uses Genius mode and skips next init sequences. At second, there is Microsoft init sequence: 0xF3 0xC8 0xF3 0x64 0xF3 0x50. After this, controller reads mouse ID (0xF2) and checks it for equivalence with 3. If it is true - mouse is in Intellimouse mode now (wheel + 3 buttons). At third, there is new Microsoft init sequence: 0xF3 0xC8 0xF3 0xC8 0xF3 0x50. After this, controller reads mouse ID again and checks it for equivalence with 4. If it is true - mouse is in Intellimouse Explorer mode now (wheel + 5 buttons). If mouse ID still is 3 - it means that it is only Intellimouse - not Explorer.
m_check	It is a code, that will be executed after 2 seconds of mouse «silence». It reads mouse status and sees stream mode flag. If stream mode is disabled - this means that mouse was reconnected. In this case controller will reset it.
p_init	Here is setting of initial values of «virtual sync serial port». It is used mainly for «re-sync» if sync was lost due to electric surge/noise (bit(s) was lost or unnecessary bit(s) was added). Additionally, this routine contains check for «alien» signal on LMB pin (for example - second joystick «fire») and disable controller.
schk	This routine receives bytes in packet buffer (byte1-byte4). After this it sets fpkt1 flag.
pchk1	This routine will be called after receiving of full packet. Because of controller is all time in «main loop» simulates mouse movement, packet processing is done by several parts. It is a first part - processing of horisontal movement. After processing this routine sets flag for next routine (fpkt2), and without own flag (fpkt1) it will not be processed again up to next packet receiving. Processing of movement contains calculating of mouse speed - movement will be done with this speed.
pchk2	This routine is like previous, and it processes vertical movement.
pchk3	This routine processes all mouse buttons (at first - standard three buttons), and then it processes additional buttons and wheel (only if these were detected).
tchk	It is a timer support. Controller updates mouse signals only approx. 6000 times per second. If next 1/6000 of second doesn't approach yet, controller will return to checking of next byte.
mchk	It is a mouse checking - as described above.
xchk ychk	It is realtime update of movement counters with needed speed.
zchk	Wheel counter update.
xyout	Movement counters and fourth button are simultaneously updated here.
cpoff	This subroutine enables controller, if it is disabled. Additionally it sets counters in default state.
testms	Check for Microsoft protocol(s). Both protocols are checked in one subroutine because of similarity (one byte difference).
send	Sending byte to mouse. Because of rare nature of this action, it is not done by interrupt engine (that also unloads interrupt routine from rare instructions).
bwait	It is a waiting for byte from mouse. Actually a byte receiving subroutine.
delayms delayus	Delays by milliseconds and fourt microseconds (in W).