G27 PS3
This is a reverse engineering of the USB interface of the G27 when connected to a PS3.
Contents
Compatibility mode
When plugged the G27 starts in compatibility mode and behaves as a Driving Force (product id 0xc294).
Enumeration
Device descriptor
| bLength | 18 |
| bDescriptorType | DEVICE (0x01) |
| bcdUSB | 2.00 (0x0200) |
| bDeviceClass | Defined in Interface (0x00) |
| bDeviceSubClass | Defined in Interface (0x00) |
| bDeviceProtocol | Defined in Interface (0x00) |
| bMaxPacketSize0 | 16 |
| idVendor | 0x046d |
| idProduct | 0xc294 |
| bcdDevice | 12.38 (0x1238) |
| iManufacturer | None (0) |
| iProduct | Not Requested (2) |
| iSerialNumber | None (0) |
| bNumConfigurations | 1 |
Configuration descriptor
Configuration Descriptor
| bLength | 9 |
| bDescriptorType | CONFIGURATION (0x02) |
| wTotalLength | 41 |
| bNumInterfaces | 1 |
| bConfigurationValue | 1 |
| iConfiguration | None (0) |
| bmAttributes.Reserved | 0 |
| bmAttributes.RemoteWakeup | RemoteWakeup Not Supported (0b0) |
| bmAttributes.SelfPowered | Bus Powered (0b0) |
| bMaxPower | 98mA (0x31) |
Interface Descriptor
| bLength | 9 |
| bDescriptorType | INTERFACE (0x04) |
| bInterfaceNumber | 0 |
| bAlternateSetting | 0 |
| bNumEndpoints | 2 |
| bInterfaceClass | Human Interface Device (0x03) |
| bInterfaceSubClass | None (0x00) |
| bInterfaceProtocol | None (0x00) |
| iInterface | None (0) |
HID Descriptor
bLength 9| bDescriptorType | HID(33) |
| bcdHID | 1.00 (0x0100) |
| bCountryCode | 0x21 |
| bNumDescriptors | 1 |
| bDescriptorType | REPORT (34) |
| wDescriptorLength | 130 |
Endpoint Descriptor
| bLength | 7 |
| bDescriptorType | ENDPOINT (0x05) |
| bEndpointAddress | 1 IN (0b10000001) |
| bmAttributes.TransferType | Interrupt (0b11) |
| wMaxPacketSize.PacketSize | 8 |
| wMaxPacketSize.Transactions | One transaction per microframe if HS (0b00) |
| bInterval | 10 |
Endpoint Descriptor
| bLength | 7 |
| bDescriptorType | ENDPOINT (0x05) |
| bEndpointAddress | 1 OUT (0b00000001) |
| bmAttributes.TransferType | Interrupt (0b11) |
| wMaxPacketSize.PacketSize | 8 |
| wMaxPacketSize.Transactions | One transaction per microframe if HS (0b00) |
| bInterval | 10 |
Report descriptor
|
|
Product string
| bLength | 34 |
| bDescriptorType | STRING (0x03) |
| bString | G27 Racing Wheel |
Get Reports (control endpoint)
FFB reports
TODO
Set Reports (control endpoint)
TODO
Interrupt IN report
| byte index | bit 7 | bit 6 | bit 5 | bit 4 | bit 3 | bit 2 | bit 1 | bit 0 |
| [0] | Wheel axis LSB (unsigned, min = 0, max = 0x03ff, center = 0x0200) | |||||||
| [1] | l1
(left shift) |
r1
(right shift) |
triangle
(up) |
circle
(right) |
square
(down) |
cross
(left) |
Wheel axis MSB | |
| [2] | 1 | 0 | r2
(top-mid-bottom right) |
l2
(top-mid-bottom left) |
oxoo
select |
ooxo
start |
ooox
r3 |
xooo
l3 |
| [3] | unknown (0x7f) | |||||||
| [4] | 1 | 0 | 0 | 0 | hat switch (D-Pad, Released=8, N=0, NE=1, E=2, SE=3, S=4, SW=5, W=6, NW=7) | |||
| [5] | gas pedal (released = 0xFF) | |||||||
| [6] | brake pedal (released = 0xFF) | |||||||
Interrupt OUT reports
TODO
Native mode
Once the native mode is enabled the G27 enumerates as a G27. Only the differences will be detailed.
Enumeration
Device descriptor
| idProduct | 0xc29b |
Configuration descriptor
Configuration Descriptor
No difference.
Interface Descriptor
| iInterface | Not Requested (254) |
HID Descriptor
| bcdHID | 1.11 (0x0111) |
| wDescriptorLength | 133 |
Endpoint Descriptor
| wMaxPacketSize.PacketSize | 16 |
| bInterval | 2 |
Endpoint Descriptor
| wMaxPacketSize.PacketSize | 16 |
| bInterval | 2 |
Report descriptor
The PS3 does not request it. It contains 3 more null bytes before the last two C0 bytes.
| 00 00 00 |
Interrupt IN report
| byte index | bit 7 | bit 6 | bit 5 | bit 4 | bit 3 | bit 2 | bit 1 | bit 0 |
| [0] | triangle | circle | square | cross | hat switch (D-Pad, Released=8, N=0, NE=1, E=2, SE=3, S=4, SW=5, W=6, NW=7) | |||
| [1] | xooo
l3 |
ooox
r3 |
ooxo
start |
oxoo
select |
l2
(wheel button left up) |
r2
(wheel button right up) |
l1
(left shifter) |
r1
(right shifter) |
| [2] | r5
(wheel button right down) |
r4
(wheel button right middle) |
gear 6 | gear 5 | gear 4 | gear 3 | gear 2 | gear 1 |
| [3] | wheel (LSB) | l5
(wheel button left down) |
l4
(wheel button left middle) | |||||
| [4] | wheel (MSB) (14-bit unsigned, min = 0, center = 0x2000, max = 0x3FFF) | |||||||
| [5] | gas pedal (released = 0xFF) | |||||||
| [6] | brake pedal (released = 0xFF) | |||||||
| [7] | clutch pedal (released = 0xFF) | |||||||
| [8] | shifter x axis (center = 0x80, left ~ 0x55, right ~ 0xab) | |||||||
| [9] | shifter y axis (center = 0x80, down ~ 0x00, up ~ 0xff) | |||||||
| [10] | 1 | reverse engaged | 0 | 1 | 1 | 1 | 0 | stick down |
