AN1077 View Datasheet(PDF) - STMicroelectronics
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MFG CO.
'AN1077' PDF : 14 Pages View PDF
OVERVIEW OF ENHANCED CAN CONTROLLERS FOR ST7 AND ST9 MCUS
Drawbacks:
s 16 mailboxes are not sufficient for body applications
s 32 mailboxes to expensive for 8-bit microcontrollers
s Static usage of mailboxes not efficient in body application.
3 BXCAN AND BECAN: THE NEW CAN SOLUTIONS
As mentioned previously for cost efficiency reasons, an 8-bit microcontroller cannot afford to
have a huge FullCAN controller with 32 mailboxes. Therefore ST’s new solutions are based on
a BasicCAN architecture, which has been extended to meet body application requirements.
3.1 BXCAN MAIN FEATURES
The basic extended CAN - called bxCAN - supports:
s CAN protocol version 2.0 A, B Active
s Bit rates up to 1Mbit/s at 8MHz
s Three transmit mailboxes
s Priority by identifier or FIFOs
s Two receive FIFO with three stages each
s Eight scalable filters
– Can be associated with FIFO 0 or 1
– Identifier list feature
– Filter match index
3.2 CAN CORE
Although the CAN core is the heart of any CAN controller, this is also the most common part.
This means that all CAN cores have to be compliant with the CAN standard and from an ap-
plication point of view do not differ from each other. The processor interface providing the
mailboxes, filters etc. must meet the application requirements and can evolve accordingly. For
this reason the bxCAN is based on the BOSCH CAN core of the C_CAN product.
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