5 interrupt generation, 6 interrupt pacing, Generation – Texas Instruments TMS320C645X User Manual
Page 85: Register, 5 interrupt generation 4.6 interrupt pacing
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4.5
Interrupt Generation
4.6
Interrupt Pacing
Interrupt Conditions
LSU bits within the ICSR are logically grouped for a given core and ORd together into a single bit of the
decode register. Similarly, the Error/Reset/Special event bits within the ICSR are ORd together into a
single bit of the decode register. When either of these bits are set in the decode register, the CPU must
make additional reads to the corresponding ICSRs to determine that exact interrupt source. It is
recommended to arrange the Doorbell ICSRs per core, so that the CPU can determine the Doorbell
interrupt source from a single read of the decode register. If the RX and TX CPPI queues are assigned
orthogonally to different cores, the CPU can determine the CPPI interrupt source from a single read of the
decode registers as well. The only exception to this is bit 31 and 30 of the decode register (TX and RX
CPPI Queues 19 and 18) which are ORd with the LSU and Error bit, respectively.
Figure 56. INTDSTn_Decode Interrupt Status Decode Register
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
ISDR3
ISDR3
ISDR2
ISDR2
ISDR2
ISDR2
ISDR2
ISDR2
ISDR2
ISDR2
ISDR2
ISDR2
ISDR1
ISDR1
ISDR1
ISDR1
1
0
9
8
7
6
5
4
3
2
1
0
9
8
7
6
R-0
R-0
R-0
R-0
R-0
R-0
R-0
R-0
R-0
R-0
R-0
R-0
R-0
R-0
R-0
R-0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
ISDR1
ISDR1
ISDR1
ISDR1
ISDR1
ISDR1
ISDR9
ISDR8
ISDR7
ISDR6
ISDR5
ISDR4
ISDR3
ISDR2
ISDR1
ISDR0
5
4
3
2
1
0
R-0
R-0
R-0
R-0
R-0
R-0
R-0
R-0
R-0
R-0
R-0
R-0
R-0
R-0
R-0
R-0
LEGEND: R = Read, W = Write, n = value at reset
Offsets:
•
INTDST0 – 0x0300
•
INTDST1 – 0x0304
•
INTDST2 – 0x0308
•
INTDST3 – 0x030C
•
INTDST4 – 0x0310
•
INTDST5 – 0x0314
•
INTDST6 – 0x0318
•
INTDST7 – 0x031C
Interrupts are triggered on a 0-to-1 logic-signal transition. Regardless of the interrupt sources, the physical
interrupts are set only when the total number of set ICSR bits transitions from none to one or more. The
peripheral is responsible for setting the correct bit within the ICSR. The ICRR register maps the pending
interrupt request to the appropriate physical interrupt line. The corresponding CPU is interrupted and
reads the ISDR and ICSR registers to determine the interrupt source and appropriate action. Interrupt
generation is governed by the interrupt pacing discussed
The rate at which an interrupt can be generated is controllable for each physical interrupt destination. Rate
control is implemented with a programmable down-counter. The load value of the counter is written by the
CPU into the appropriate interrupt rate control register (see
). The counter reloads and
immediately starts down-counting each time the CPU writes these registers. When the rate control counter
register is written, and the counter value reaches zero (note that the CPU may write zero immediately for
a zero count), the interrupt pulse generation logic is allowed to fire a single pulse if any bits in the
corresponding ICSR register bits are set (or become set after the zero count is reached). The counter
remains at zero. When the single pulse is generated, the logic will not generate another pulse, regardless
of interrupt status changes, until the rate control counter register is written again. If interrupt pacing is not
desired for a particular INTDST, the CPU must still write 0x00000000 into the INTDSTn_RATE_CNTL
register after clearing the corresponding ICSR bits to acknowledge the physical interrupt. If an ICSR is not
mapped to an interrupt destination, pending interrupt bits within the ICSR maintain current status. Once
enabled, the interrupt logic re-evaluates all pending interrupts and re-pulses the interrupt signal if any
interrupt conditions are pending. The down-counter is based on the DMA clock cycle.
SPRU976 – March 2006
Serial RapidIO (SRIO)
85