AN2283 Freescale Semiconductor / Motorola, AN2283 Datasheet - Page 40

• Manufacturer Part Number: AN2283
• Description: Scalable Controller Area Network (MSCAN)
• Manufacturer: Freescale Semiconductor / Motorola

AN2283/D
Overrun Interrupt
Summary
References
40
Motorola Scalable Controller Area Network (MSCAN) Interrupts
An Overrun Interrupt occurs when a new incoming message appears on the
CAN bus when both the RxBG and RxFG buffers contain correctly received and
filtered messages. To enable the Overrun Interrupt, set the OVRIE (Overrun
Interrupt Enable) bit in CRIER which will result in an Overrun Interrupt when the
OVRIF flag sets in CRFLG. The new message and all further incoming
messages will be ignored until the Foreground Receive Buffer (RxFG) is
released. The MSCAN will stay synchronized to the CAN bus and is able to
transmit messages. To prevent the Overrun Condition, the receive handler
software must read the contents of the RxFG buffer and release it before the
RxBG buffer is filled with the next filtered message.
This application note covers the interrupts and their operation on the
MSCAN08 (for the HC08 Family) and MSCAN12 (for the HC12 Family). The
example interrupt service routine flowcharts
the minimal steps necessary to service each interrupt, but user’s actual
interrupt routines will vary depending on system requirements. Please refer to
the relevant MSCAN and microcontroller unit (MCU) manuals for a complete
description of the registers and other non-interrupt details of specific devices
(see References).
1. CAN Bosch Controller Area Network (CAN) Version 2.0 Protocol
2. ISO 11898 — can be found on the World Wide Web at:
3. M68HC12B Family Advance Information (Motorola document order
4. 68HC912D60/68HC12D60 Advance Information (Motorola document
5. MC68HC912D60A Technical Data (Motorola document order number
6. MC68HC912DT128A/MC68HC912DG128A Technical Data (Motorola
7. MC68HC08AZ32 Advance Information (Motorola document order
8. MC68HC08AZ32A Advance Information (Motorola document order
Freescale Semiconductor, Inc.
For More Information On This Product,
Standard (order number BCANPSV2.0/D)
http://www.iso.org/iso/en/CatalogueDetailPage.CatalogueDetail?CSNU
MBER=20380&ICS1=43&ICS2=40&ICS3=15
number M68HC12B/D)
order number MC68HC912D60/D)
MC68HC912D60A/D)
document order number MC68HC912DT128A/D)
number MC68HC08AZ32/D)
number MC68HC08AZ32A/D)
Go to: www.freescale.com
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