PIC18F2480 MICROCHIP [Microchip Technology], PIC18F2480 Datasheet - Page 342

• Manufacturer Part Number: PIC18F2480
• Description: 28/40/44-Pin Enhanced Flash Microcontrollers with ECAN Technology, 10-Bit A/D and nanoWatt Technology
• Manufacturer: MICROCHIP [Microchip Technology]

PIC18F2480/2580/4480/4580
23.15.1
To simplify the interrupt handling process in user firm-
ware, the ECAN module encodes a special set of bits. In
Mode 0, these bits are ICODE<3:1> in the CANSTAT
register. In Mode 1 and 2, these bits are EICODE<4:0> in
the CANSTAT register. Interrupts are internally prioritized
such that the higher priority interrupts are assigned lower
values. Once the highest priority interrupt condition has
been cleared, the code for the next highest priority inter-
rupt that is pending (if any) will be reflected by the ICODE
bits (see Table 23-5). Note that only those interrupt
sources that have their associated interrupt enable bit set
will be reflected in the ICODE bits.
In Mode 2, when a receive message interrupt occurs,
the EICODE bits will always consist of ‘10000’. User
firmware may use FIFO pointer bits to actually access
the next available buffer.
23.15.2
When the transmit interrupt is enabled, an interrupt will
be generated when the associated transmit buffer
becomes empty and is ready to be loaded with a new
message. In Mode 0, there are separate interrupt
enable/disable and flag bits for each of the three dedi-
cated transmit buffers. The TXBnIF bit will be set to indi-
cate the source of the interrupt. The interrupt is cleared
by the MCU, resetting the TXBnIF bit to a ‘0’. In Mode 1
and 2, all transmit buffers share one interrupt enable/
disable bit and one flag bit. In Mode 1 and 2, TXBIE in
PIE3 and TXBIF in PIR3 indicate when a transmit buffer
has completed transmission of its message. TXBnIF,
TXBnIE and TXBnIP in PIR3, PIE3 and IPR3, respec-
tively, are not used in Mode 1 and 2. Individual transmit
buffer interrupts can be enabled or disabled by setting or
clearing TXBIE and B0IE register bits. When a shared
interrupt occurs, user firmware must poll the TXREQ bit
of all transmit buffers to detect the source of interrupt.
23.15.3
When the receive interrupt is enabled, an interrupt will
be generated when a message has been successfully
received and loaded into the associated receive buffer.
This interrupt is activated immediately after receiving
the End-Of-Frame (EOF) field.
In Mode 0, the RXBnIF bit is set to indicate the source
of the interrupt. The interrupt is cleared by the MCU,
resetting the RXBnIF bit to a ‘0’.
In Mode 1 and 2, all receive buffers share RXBIE,
RXBIF and RXBIP in PIE3, PIR3 and IPR3, respec-
tively. Bits RXBnIE, RXBnIF and RXBnIP are not used.
Individual receive buffer interrupts can be controlled by
the TXBIE and BIE0 registers. In Mode 1, when a
shared receive interrupt occurs, user firmware must
poll the RXFUL bit of each receive buffer to detect the
source of interrupt. In Mode 2, a receive interrupt
indicates that the new message is loaded into FIFO.
FIFO can be read by using FIFO Pointer bits, FP.
DS39637A-page 340
INTERRUPT CODE BITS
TRANSMIT INTERRUPT
RECEIVE INTERRUPT
Preliminary
TABLE 23-5:
23.15.4
When an error occurs during transmission or reception
of a message, the message error flag, IRXIF, will be set
and if the IRXIE bit is set, an interrupt will be generated.
This is intended to be used to facilitate baud rate
determination when used in conjunction with Listen
Only mode.
23.15.5
When the PIC18F2480/2580/4480/4580 devices are in
Sleep mode and the bus activity wake-up interrupt is
enabled, an interrupt will be generated and the WAKIF
bit will be set when activity is detected on the CAN bus.
This interrupt causes the PIC18F2480/2580/4480/
4580 devices to exit Sleep mode. The interrupt is reset
by the MCU, clearing the WAKIF bit.
23.15.6
When the error interrupt is enabled, an interrupt is
generated if an overflow condition occurs or if the error
state of the transmitter or receiver has changed. The
error flags in COMSTAT will indicate one of the
following conditions.
Legend:
ERR = ERRIF * ERRIE
TX0 = TXB0IF * TXB0IE RX1 = RXB1IF * RXB1IE
TX1 = TXB1IF * TXB1IE WAK = WAKIF * WAKIE
TX2 = TXB2IF * TXB2IE
ICODE
<2:0>
000
001
010
011
100
101
110
111
Interrupt
Wake on
Interrupt
RXB1
RXB0
TXB2
TXB1
TXB0
None
Error
MESSAGE ERROR INTERRUPT
BUS ACTIVITY WAKE-UP
INTERRUPT
ERROR INTERRUPT
VALUES FOR ICODE<2:0>
ERR•WAK•TX0•TX1•TX2•RX0•RX1
ERR
ERR•TX0•TX1•TX2
ERR•TX0•TX1
ERR•TX0
ERR•TX0•TX1•TX2•RX0•RX1
ERR•TX0•TX1•TX2•RX0
ERR•TX0•TX1•TX2•RX0•RX1•WAK
 2004 Microchip Technology Inc.
Boolean Expression
RX0 = RXB0IF * RXB0IE