Arm
®
CoreLink™ GIC-600AE Generic Interrupt Controller
Technical Reference Manual
Document ID: 101206_0003_04_en
Issue: 04
Functional Safety
Since the GIC-600AE SAF detector counts to 16 before flagging an SAF, the permitted skew is
calculated as follows:
•
Maximum skew allowed = 16/CR.
Example 6-2: Interrupt skew calculation
•
GIC clock frequency = 800MHz
•
Interrupt source frequency = 200MHz
Based on these frequencies, then:
•
CR = (GIC clock frequency)/(channel controller clock frequency) = 800MHz / 200MHz = 4
•
Maximum skew allowed = 16 / CR = 16 / 4 = 4 cycles
Therefore, the system integrator is allowed four cycles for implementation skew and temporal delay
skew that originate from the interrupt source IP.
6.11.2 PPI and SPI transient faults
If a corresponding spi_chk signal edge is not detected within 16 cycles, a transient fault is reported.
The following figure shows an assertion of an spi signal that causes a transient fault.
Figure 6-27: Transient fault on spi
Error
spi
clk
spi_chk
15
14
Count
13 12 11 2 1 0
spi_int
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