CP3BT23_14 Datasheet, PDF (147/324 Pages) Texas Instruments – CP3BT23 Reprogrammable Connectivity Processor with Bluetooth and Dual CAN Interfaces

CP3BT23
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CAN Interrupt Request
No Request
Error Interrupt
Buffer 0
Buffer 1
Buffer 2
Buffer 3
Buffer 4
Buffer 5
Buffer 6
Buffer 7
Buffer 8
Buffer 9
Buffer 10
Buffer 11
Buffer 12
Buffer 13
Buffer 14
SNOSCX3A – JULY 2013 – REVISED JANUARY 2014
Table 18-6. Highest Priority Interrupt Code (ICEN=FFFF)
IRQ
IST3
IST2
IST1
IST0
0
0
0
0
0
1
0
0
0
0
1
0
0
0
1
1
0
0
1
0
1
0
0
1
1
1
0
1
0
0
1
0
1
0
1
1
0
1
1
0
1
0
1
1
1
1
1
0
0
0
1
1
0
0
1
1
1
0
1
0
1
1
0
1
1
1
1
1
0
0
1
1
1
0
1
1
1
1
1
0
1
1
1
1
1
18.7.2 Usage Hints
The interrupt code IST3:0 can be used within the interrupt handler as a displacement to jump to the
relevant subroutine.
The CAN Interrupt Code Enable (CICEN) register is used in the CAN interrupt handler if software is
servicing all receive buffer interrupts first, followed by all transmit buffer interrupts. In this case, software
can first enable only receive buffer interrupts to be coded, then scan and service all pending interrupt
requests in the order of their priority. After processing all the receive interrupts, software changes the
CICEN register to disable all receive buffers and enable all transmit buffers, then services all pending
transmit buffer interrupt requests according to their priorities.
18.8 TIME STAMP COUNTER
The CAN module features a free running 16-bit timer (CTMR) incrementing every bit time recognized on
the CAN bus. The value of this timer during the ACK slot is captured into the TSTP register of a message
buffer after a successful transmission or reception of a message. Figure 18-27 shows a simplified block
diagram of the Time Stamp counter.
CAN bits on the bus
ACK slot and buffer 0 active
+ 1 _{16-Bit counter}
Reset
ACK slot
TSTP register
DS044
Figure 18-27. Time Stamp Counter
The timer can be synchronized over the CAN network by receiving or transmitting a message to or from
buffer 0. In this case, the TSTP register of buffer 0 captures the current CTMR value during the ACK slot
of a message (as above), and then the CTMR is reset to 0000b. Synchronization can be enabled or
disabled using the CGCR.TSTPEN bit.
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