LM3S2965 Datasheet, PDF (412/542 Pages) List of Unclassifed Manufacturers – Microcontroller

Controller Area Network (CAN) Module
tProp 600 ns = 6 × tq
tSJW 100 ns = 1 × tq
tTSeg1 700 ns = tProp + tSJW
tTSeg2 200 ns = Information Processing Time + 1 × tq
tSync-Seg 100 ns = 1 × tq
bit time 1000 ns = tSync-Seg + tTSeg1 + tTSeg2
tolerance for CAN_CLK 0.39 % =
min(PB1,PB2)/ 2 × (13 x bit time - PB2) =
0.1us/ 2 x (13x 1us - 2us)
In the above example, the concatenated bit time parameters are (2-1)3&(7-1)4&(1-1)2&(1-1)6, and
CANBIT is programmed to 0x1600.
16.4.15.2 Example for Bit Timing at Low Baud Rate
In this example, the frequency of CAN_CLK is 2 MHz, BRP is 1, and the bit rate is 100 Kbps.
tq 1 ms = 2 × tCAN_CLK
delay of bus driver 200 ns
delay of receiver circuit 80 ns
delay of bus line (40m) 220 ns
tProp 1 ms = 1 × tq
tSJW 4 ms = 4 × tq
tTSeg1 5 ms = tProp + tSJW
tTSeg2 4 ms = Information Processing Time + 3 × tq
tSync-Seg 1 ms = 1 × tq
bit time 10 ms = tSync-Seg + tTSeg1 + tTSeg2
tolerance for CAN_CLK 1.58 % =
min(PB1,PB2)/ 2 x (13 x bit time - PB2) =
4us/ 2 x (13 x 10us - 4us)
In this example, the concatenated bit time parameters are (4-1)3&(5-1)4&(4-1)2&(2-1)6, and CANBIT
is programmed to 0x34C1.
16.5
Controller Area Network Register Map
“Controller Area Network Register Map” on page 412 lists the registers. All addresses given are
relative to the CAN base address of:
■ CAN0: 0x4004.0000
■ CAN1: 0x4004.1000
All accesses are on word (32-bit) boundaries.
Table 16-4. CAN Register Map
Offset Name
Type
0x000 CANCTL
R/W
0x004 CANSTS
R/W
0x008 CANERR
RO
Reset
0x0000.0001
0x0000.0000
0x0000.0000
Description
CAN Control
CAN Status
CAN Error Counter
See
page
415
417
420
412
June 04, 2007
Preliminary