Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 254 insertions, 0 deletions

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+** Introduction

+This document describes what I managed to discover about the protocol used to

+specify force effects to I-Force 2.0 devices.  None of this information comes

+from Immerse. That's why you should not trust what is written in this

+document. This document is intended to help understanding the protocol.

+This is not a reference. Comments and corrections are welcome.  To contact me,

+send an email to: deneux@ifrance.com

+

+** WARNING **

+I may not be held responsible for any dammage or harm caused if you try to

+send data to your I-Force device based on what you read in this document.

+

+** Preliminary Notes:

+All values are hexadecimal with big-endian encoding (msb on the left). Beware,

+values inside packets are encoded using little-endian.  Bytes whose roles are

+unknown are marked ???  Information that needs deeper inspection is marked (?)

+

+** General form of a packet **

+This is how packets look when the device uses the rs232 to communicate.

+2B OP LEN DATA CS

+CS is the checksum. It is equal to the exclusive or of all bytes.

+

+When using USB:

+OP DATA

+The 2B, LEN and CS fields have disappeared, probably because USB handles frames and

+data corruption is handled or unsignificant.

+

+First, I describe effects that are sent by the device to the computer

+

+** Device input state

+This packet is used to indicate the state of each button and the value of each

+axis

+OP= 01 for a joystick, 03 for a wheel

+LEN= Varies from device to device

+00 X-Axis lsb

+01 X-Axis msb

+02 Y-Axis lsb, or gas pedal for a wheel

+03 Y-Axis msb, or brake pedal for a wheel

+04 Throttle

+05 Buttons

+06 Lower 4 bits: Buttons

+   Upper 4 bits: Hat

+07 Rudder

+

+** Device effects states

+OP= 02

+LEN= Varies

+00 ? Bit 1 (Value 2) is the value of the deadman switch

+01 Bit 8 is set if the effect is playing. Bits 0 to 7 are the effect id.

+02 ??

+03 Address of parameter block changed (lsb)

+04 Address of parameter block changed (msb)

+05 Address of second parameter block changed (lsb)

+... depending on the number of parameter blocks updated

+

+** Force effect **

+OP=  01

+LEN= 0e

+00 Channel (when playing several effects at the same time, each must be assigned a channel)

+01 Wave form

+	Val 00 Constant

+	Val 20 Square

+	Val 21 Triangle

+	Val 22 Sine

+	Val 23 Sawtooth up

+	Val 24 Sawtooth down

+	Val 40 Spring (Force = f(pos))

+	Val 41 Friction (Force = f(velocity)) and Inertia (Force = f(acceleration))

+

+	

+02 Axes affected and trigger

+	Bits 4-7: Val 2 = effect along one axis. Byte 05 indicates direction

+	          Val 4 = X axis only. Byte 05 must contain 5a

+	          Val 8 = Y axis only. Byte 05 must contain b4

+	          Val c = X and Y axes. Bytes 05 must contain 60

+	Bits 0-3: Val 0 = No trigger

+	          Val x+1 = Button x triggers the effect

+	When the whole byte is 0, cancel the previously set trigger

+

+03-04 Duration of effect (little endian encoding, in ms)

+

+05 Direction of effect, if applicable. Else, see 02 for value to assign.

+

+06-07 Minimum time between triggering.

+

+08-09 Address of periodicity or magnitude parameters

+0a-0b Address of attack and fade parameters, or ffff if none.

+*or*

+08-09 Address of interactive parameters for X-axis, or ffff if not applicable

+0a-0b Address of interactive parameters for Y-axis, or ffff if not applicable

+

+0c-0d Delay before execution of effect (little endian encoding, in ms)

+

+

+** Time based parameters **

+

+*** Attack and fade ***

+OP=  02

+LEN= 08

+00-01 Address where to store the parameteres

+02-03 Duration of attack (little endian encoding, in ms)

+04 Level at end of attack. Signed byte.

+05-06 Duration of fade.

+07 Level at end of fade.

+

+*** Magnitude ***

+OP=  03

+LEN= 03

+00-01 Address

+02 Level. Signed byte.

+

+*** Periodicity ***

+OP=  04

+LEN= 07

+00-01 Address

+02 Magnitude. Signed byte.

+03 Offset. Signed byte.

+04 Phase. Val 00 = 0 deg, Val 40 = 90 degs.

+05-06 Period (little endian encoding, in ms)

+

+** Interactive parameters **

+OP=  05

+LEN= 0a

+00-01 Address

+02 Positive Coeff

+03 Negative Coeff

+04+05 Offset (center)

+06+07 Dead band (Val 01F4 = 5000 (decimal))

+08 Positive saturation (Val 0a = 1000 (decimal) Val 64 = 10000 (decimal))

+09 Negative saturation

+

+The encoding is a bit funny here: For coeffs, these are signed values. The

+maximum value is 64 (100 decimal), the min is 9c.

+For the offset, the minimum value is FE0C, the maximum value is 01F4.

+For the deadband, the minimum value is 0, the max is 03E8.

+

+** Controls **

+OP=  41

+LEN= 03

+00 Channel

+01 Start/Stop

+	Val 00: Stop

+	Val 01: Start and play once.

+	Val 41: Start and play n times (See byte 02 below)

+02 Number of iterations n.

+

+** Init **

+

+*** Querying features ***

+OP=  ff

+Query command. Length varies according to the query type.

+The general format of this packet is:

+ff 01 QUERY [INDEX] CHECKSUM

+reponses are of the same form:

+FF LEN QUERY VALUE_QUERIED CHECKSUM2

+where LEN = 1 + length(VALUE_QUERIED)

+

+**** Query ram size ****

+QUERY = 42 ('B'uffer size)

+The device should reply with the same packet plus two additionnal bytes

+containing the size of the memory:

+ff 03 42 03 e8 CS would mean that the device has 1000 bytes of ram available.

+

+**** Query number of effects ****

+QUERY = 4e ('N'umber of effects)

+The device should respond by sending the number of effects that can be played

+at the same time (one byte)

+ff 02 4e 14 CS would stand for 20 effects.

+

+**** Vendor's id ****

+QUERY = 4d ('M'anufacturer)

+Query the vendors'id (2 bytes)

+

+**** Product id *****

+QUERY = 50 ('P'roduct)

+Query the product id (2 bytes)

+

+**** Open device ****

+QUERY = 4f ('O'pen) 

+No data returned.

+

+**** Close device *****

+QUERY = 43 ('C')lose

+No data returned.

+

+**** Query effect ****

+QUERY = 45 ('E') 

+Send effect type.

+Returns nonzero if supported (2 bytes)

+

+**** Firmware Version ****

+QUERY = 56 ('V'ersion)

+Sends back 3 bytes - major, minor, subminor

+

+*** Initialisation of the device ***

+

+**** Set Control ****

+!!! Device dependent, can be different on different models !!!

+OP=  40 <idx> <val> [<val>]

+LEN= 2 or 3

+00 Idx

+   Idx 00 Set dead zone (0..2048) 

+   Idx 01 Ignore Deadman sensor (0..1)     

+   Idx 02 Enable comm watchdog (0..1)     

+   Idx 03 Set the strength of the spring (0..100)   

+   Idx 04 Enable or disable the spring (0/1)

+   Idx 05 Set axis saturation threshold (0..2048) 

+

+**** Set Effect State ****

+OP=  42 <val>

+LEN= 1

+00 State

+   Bit 3 Pause force feedback

+   Bit 2 Enable force feedback

+   Bit 0 Stop all effects

+

+**** Set overall gain ****

+OP=  43 <val>

+LEN= 1

+00 Gain

+   Val 00 = 0%

+   Val 40 = 50%

+   Val 80 = 100%

+

+** Parameter memory **

+

+Each device has a certain amount of memory to store parameters of effects.

+The amount of RAM may vary, I encountered values from 200 to 1000 bytes. Below

+is the amount of memory apparently needed for every set of parameters:

+ - period : 0c

+ - magnitude : 02

+ - attack and fade : 0e

+ - interactive : 08

+

+** Appendix: How to study the protocol ? **

+

+1. Generate effects using the force editor provided with the DirectX SDK, or use Immersion Studio (freely available at their web site in the developer section: www.immersion.com)

+2. Start a soft spying RS232 or USB (depending on where you connected your joystick/wheel). I used ComPortSpy from fCoder (alpha version!)

+3. Play the effect, and watch what happens on the spy screen.

+

+A few words about ComPortSpy:

+At first glance, this soft seems, hum, well... buggy. In fact, data appear with a few seconds latency. Personnaly, I restart it every time I play an effect.

+Remember it's free (as in free beer) and alpha!

+

+** URLS **

+Check www.immerse.com for Immersion Studio, and www.fcoder.com for ComPortSpy.

+

+** Author of this document **

+Johann Deneux <deneux@ifrance.com>

+Home page at http://www.esil.univ-mrs.fr/~jdeneux/projects/ff/

+

+Additions by Vojtech Pavlik.

+

+I-Force is trademark of Immersion Corp.