ADSP-BF537 Blackfin Processor Hardware Reference
9-35
CAN Module
The mode auto acknowledge bit (
MAA
) allows the CAN module to generate
its own acknowledge during the ACK slot of the CAN frame. No external
devices or connections are necessary to read back a transmit message. In
this mode, the message that is sent is automatically stored in the internal
receive buffer. In auto acknowledge mode, the module itself transmits the
acknowledge. This acknowledge can be programmed to appear on the
CANTX
pin if
DIL=1
and
DTO=0
. If the acknowledge is only going to be used
internally, then these test mode bits should be set to
DIL=0
and
DTO=1
.
The disable internal loop bit (
DIL
) is used to internally enable the transmit
output to be routed back to the receive input.
The disable transmit output bit (
DTO
) is used to disable the
CANTX
output
pin. When this bit is set, the
CANTX
pin continuously drives recessive bits.
The disable receive input bit (
DRI
) is used to disable the
CANRX
input.
When set, the internal logic receives recessive bits or receives the internally
generated transmit value in the case of the internal loop enabled (
DIL=0
).
In either case, the value on the
CANRX
input pin is ignored.
The disable error counters bit (
DEC
) is used to disable the transmit and
receive error counters in the
CAN_CEC
register. When this bit is set, the
CAN_CEC
holds its current contents and is not allowed to increment or dec-
rement the error counters. This mode does not conform to the CAN
specification.
L
Writes to the error counters should be in debug mode only. Write
access during reception may lead to undefined values. The maxi-
mum value which can be written into the error counters is 255.
Thus, the error counter value of 256 which forces the module into
the bus off state can not be written into the error counters.
shows several common combinations of test mode bits.
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 ...