Determining The Can Controller's Interrupt Status - Intel 8XC196K Series User Manual

8XC196K x , J x , CA USER'S MANUAL

12.7 DETERMINING THE CAN CONTROLLER'S INTERRUPT STATUS

A successful reception or transmission or a change in the status register can cause the CAN con-
troller to generate an interrupt request. The INT_PEND1 register (see Table 12-2 on page 12-3)
indicates whether a CAN interrupt request is pending. The CAN interrupt pending register (Fig-
ure 12-19) indicates the source of the request (either the status register or a specific message ob-
ject). Your interrupt service routine should read the CAN_INT register to ensure that no
additional interrupts are pending before executing the return instruction. Chapter 5, "Standard
and PTS Interrupts," discusses interrupt service, relative priorities, and timing.
CAN_INT
read-only (87C196CA)
The CAN interrupt pending (CAN_INT) register indicates the source of the highest priority pending
interrupt. If a status change generated the interrupt request, software can read the status register
(CAN_STAT) to determine whether the interrupt request was caused by an abnormal error rate, a
successful reception, a successful transmission, or a new error. If an individual message object
generated the interrupt request, software can read the associated message object control 0 register
(CAN_MSG x CON0). The INT_PND bit-pair will be set, indicating that a receive or transmit interrupt
request is pending.
7
87C196CA
Bit
Number
7:0 Pending Interrupt
This field indicates the source of the highest priority pending interrupt.
Value
00H
01H
02H
03H
04H
05H
06H
07H
08H
09H
0AH
0BH
0CH
0DH
0EH
0FH
10H
Figure 12-19. CAN Interrupt Pending (CAN_INT) Register
12-32
Pending Interrupt
Pending Interrupt Priority (15 is highest; 0 is lowest)
none —
status register 15
message object 15 14
message object 1 13
message object 2 12
message object 3 11
message object 4 10
message object 5 9
message object 6 8
message object 7 7
message object 8 6
message object 9 5
message object 10 4
message object 11 3
message object 12 2
message object 13 1
message object 14 0
Reset State:
Function
Address: 1E5FH
00H
0