ADSP-BF537 Blackfin Processor Hardware Reference
9-9
CAN Module
The next field of interest is the
IDE
. When set, it indicates that the mes-
sage is an extended frame with a 29-bit identifier instead of an 11-bit
identifier. In an extended frame, the first part of the message resembles
As could be concluded with regards to the
RTR
field, a dominant bit in the
IDE
field wins arbitration against an extended frame with the same lower
11-bits, therefore, standard frames are higher priority than extended
frames. The substitute remote request bit (
SRR
, always sent as recessive),
the reserved bits
r0
and
r1
(always sent as dominant), and the checksum
(
CRC
) are generated automatically by the internal logic.
CAN Operation
The CAN controller is in configuration mode when coming out of proces-
sor reset or hibernate. It is only when the CAN is in configuration mode
that hardware behavior can be altered. Before initializing the mailboxes
themselves, the CAN bit timing must be set up to work on the CAN bus
that the controller is expected to connect to.
Bit Timing
The CAN controller does not have a dedicated clock. Instead, the CAN
clock is derived from the system clock (
SCLK
) based on a configurable
number of time quanta. The Time Quantum (TQ) is derived from the
formula
TQ
= (
BRP
+
1
)/
SCLK
, where
BRP
is the 10-bit
BRP
field in the
Figure 9-6. Extended CAN Frame
SOF
IDENTIFIER
SRR
1
11
1
1
18
1
1
4
RTR
IDE
r1
1
IDENTIFIER
r0
DLC
Summary of Contents for Blackfin ADSP-BF537
Page 42: ...Contents xlii ADSP BF537 Blackfin Processor Hardware Reference ...
Page 90: ...Development Tools 1 32 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 138: ...Programming Examples 4 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 340: ...SDC Programming Examples 6 84 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 606: ...Programming Examples 9 94 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 660: ...Programming Examples 10 54 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 720: ...Electrical Specifications 11 60 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 840: ...Programming Examples 13 42 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 876: ...Programming Examples 14 36 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 938: ...Programming Examples 15 62 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 958: ...Programming Examples 17 12 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 986: ...Programming Examples 18 28 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 1162: ...G 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 1218: ...Index I 56 ADSP BF537 Blackfin Processor Hardware Reference ...