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announce.md

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0x02 "Pong" & Announce

This command has two purposes:

  1. Annoucing the presence of a module on the bus.
  2. "Pong" in response to a "Ping" 0x01.

Examples

The length of the message does not vary. The single data byte is a bitmask.

60 04 F0 02 00 96
3B 04 C8 02 10 E5
BB 04 68 02 00 D5

Bitmasks

ANNOUNCE    = 0b0000_0001 << 0
SIGNATURE   = 0b1111_0000 << 0
Bit 7 6 5 4 3 2 1 0
Use Signature Signature Signature Signature - - - Announce

Properties

Announce 0b0000_0001

REPLY       = 0b0000_0000
ANNOUNCE    = 0b0000_0001

The announce bit is set when a module becomes active on the bus. This is most frequently seen at ignition with modules commonly powered/activated by ignition circuits (KL-R, KL-15).

C8 04 FF 02 31 00       # Telephone broadcasting an announcement

The announcement is what determines the availability of numerous features. For example, Television, Telephone, and DSP will all appear in the BMBT main menu following announcement.

An annoucement also allows the new module to establish it's state. and any applicable modules will respond as necessary. The response will depend on the announcing module, but will at minimum, include ignition state 0x11 from the cluster.

After a module has announced, it's ongoing presence will be checked by interested modules via "pings" 0x01, for which this bit will never be set.

C8 04 FF 02 30 01       # Telephone replying to a "ping" (no announce bit!)

Signature 0b1111_0000

In the case that a module has variants, and that variant affects behaviour of other modules on the bus, a "signature" is used to allow variants to be identified.

A good working example of this is the BMBT which was introduced with the 4x3 display, and was later upgraded to the larger 16x9 display. In order for the navi. computer/video module to output a video signal with the correct aspect ratio, it must be able to identify the BMBT variant.

GT 0x3b

Module Variant Signature Frame
GT Video Module GT 0x10 3B 04 FF 02 11 D3
GT Nav. GT (incl. MK1) 0x40 3B 04 BF 02 41 C3

Nav. Computer 0x7f

Module Variant Signature Frame
Nav. MK4? 0x40 7F 04 BF 02 41 87
Nav. MK4? + BMW Assist 0xc0 7F 04 BF 02 C1 07
  • telephone to presumably configure BMW Assist
  • may affect MRS and sending impact notification

Telephone 0xc8

Module Variant Signature Frame
Telephone CMT3000 0x00 C8 04 FF 02 01 30
Telephone Motorola V-Series 0x30 C8 04 FF 02 31 00
  • nav. computer will send telematics data 0xa2, 0xa4

BMBT 0xf0

Module Variant Signature Frame
BMBT 4x3 0x00 F0 04 BF 02 01 48
BMBT 16x9 0x30 F0 04 BF 02 31 78
  • GT/VM will set correct aspect ratio and encoding.

No Signatures

While the need for a signature is likely predicated upon a module hardware/software revision, it's only in the case that the module must be differentiated on the bus that a signature will be used. Some modules, despite having one or more revisions, will not distinguish variants.

The following module variants do not appear to have a signature:

Module Module ID Variant Signature Frame
GM 0x00 GM III (E39) 0x00 00 04 BF 02 01 B8
CDC 0x18 All? 0x00 18 04 BF 02 01 A0
CCM 0x30 All? 0x00 30 04 BF 02 01 88
PDC 0x60 All? 0x00 60 04 BF 02 01 D8
Radio 0x68 C23 BM 0x00 68 04 FF 02 01 90
Radio 0x68 BM53 0x00 68 04 BF 02 01 D0
IKE 0x80 IKE, IKI, KOMBI 0x00 80 04 BF 02 01 38
EHC 0xAC All? 0x00 AC 04 BF 02 01 14
LCM 0xD0 LCM III (E39) 0x00 D0 04 BF 02 01 68
TV 0xED MK1 VM, "MK3" VM 0x00 ED 04 FF 02 01 15