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Specify a software filter accepting only the messages that pass the filter test.
There are 3 possible filter modes:
CAN.FILTER_LIST allows to pass the list of IDs that should be accepted.
CAN.FILTER_RANGE allows to pass a list or tuple of ID ranges that should be
accepted.
CAN.FILTER_MASK allows to pass a list of tuples of the form:
(filer, mask)
.
With software filters all messages in the bus are received by the CAN controller but only the
matching ones are passed to the RX queue. This means that the queue won't be filled up
with non relevant messages, but the interrupt overhead will remain as normal. The
filter_list
can contain up to 32 elements.
For example:
can.soft_filter(CAN.FILTER_LIST, [ 0x100 , 0x200 , 0x300 , 0x400 ]) # only accept identifi
ers from 0x100, 0x200, 0x300 and 0x400
can.soft_filter(CAN.FILTER_RANGE, [( 0x001 , 0x010 ), ( 0x020 , 0x030 ), ( 0x040 , 0x050 )]) #
only accept identifiers from 0x001 to 0x010, from 0x020 to 0x030 and from 0x040 to 0x
050.
can.soft_filter(CAN.FILTER_MASK, [( 0x100 , 0x7FF ), ( 0x200 , 0x7FC )]) # more of the class
ic Filter and Mask method.
can.soft_filter( None ) # disable soft filters, all messages are accepted
can.callback(trigger, handler=None, arg=None)
Set a callback to be triggered when any of this 3 events are present:
trigger is the type of event that triggers the callback. Possible values are:
CAN.RX_FRAME interrupt whenever a new frame is received.
CAN.RX_FIFO_NOT_EMPTY interrupt when a frame is received on an empty
FIFO.
CAN.RX_FIFO_OVERRUN interrupt when a message is received and the FIFO is
full.
The values can be OR-ed together, for instance trigger=CAN.RX_FRAME |
CAN.RX_FIFO_OVERRUN
handler is the function to be called when the event happens. This function will receive
one argument. Set handler to None to disable the callback.
arg is an optional argument to pass to the callback. If left empty or set to None, the
function will receive the CAN object that triggered it.
5.2.1.12 CAN
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