2000 Jan 04 41
Philips Semiconductors Product specification
Stand-alone CAN controller SJA1000
Table 30 TX identifier 2 (EFF); CAN address 18; note 1
Note
1. ID.X means identifier bit X.
Table 31 TX identifier 3 (EFF); CAN address 19; note 1
Note
1. ID.X means identifier bit X.
Table 32 TX identifier 4 (EFF); CAN address 20; note 1
Notes
1. ID.X means identifier bit X.
2. Don’t care; recommended to be compatible to receive buffer (RTR) in case of using the self reception facility (self
test).
3. Don’t care; recommended to be compatible to receive buffer (0) in case of using the self reception facility (self test).
Table 33 Frame Format (FF) and Remote Transmission Request (RTR) bits
BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0
ID.20 ID.19 ID.18 ID.17 ID.16 ID.15 ID.14 ID.13
BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0
ID.12 ID.11 ID.10 ID.9 ID.8 ID.7 ID.6 ID.5
BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0
ID.4 ID.3 ID.2 ID.1 ID.0 X
(2)
X
(3)
X
(3)
BIT VALUE FUNCTION
FF 1 EFF; extended frame format will be transmitted by the CAN controller
0 SFF; standard frame format will be transmitted by the CAN controller
RTR 1 remote; remote frame will be transmitted by the CAN controller
0 data; data frame will be transmitted by the CAN controller
6.4.13.3 Data Length Code (DLC)
The number of bytes in the data field of a message is
coded by the data length code. At the start of a remote
frame transmission the data length code is not considered
due to the RTR bit being logic 1 (remote). This forces the
number of transmitted/received data bytes to be 0.
Nevertheless, the data length code must be specified
correctly to avoid bus errors, if two CAN controllers start a
remote frame transmission with the same identifier
simultaneously.
The range of the data byte count is 0 to 8 bytes and is
coded as follows:
DataByteCount = 8 × DLC.3 + 4 × DLC.2 + 2 × DLC.1 +
DLC.0
For reasons of compatibility no data length code >8 should
be used. If a value >8 is selected, 8 bytes are transmitted
in the data frame with the Data Length Code specified in
DLC.
6.4.13.4 Identifier (ID)
In Standard Frame Format (SFF) the identifier consists of
11 bits (ID.28 to ID.18) and in Extended Frame Format
(EFF) messages the identifier consists of 29 bits
(ID.28 to ID.0). ID.28 is the most significant bit, which is
transmitted first on the bus during the arbitration process.
The identifier acts as the message’s name, used in a
receiver for acceptance filtering, and also determines the
bus access priority during the arbitration process.
