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AS3935

Datasheet - Detailed Descri p ti on

The calculated energy is stored in registers REG0x04[7:0], REG0x05[7:0] and REG0x06[4:0].

8.9.4 Interrupt Management

Whenever events happen, the AS3935 pulls the IRQ high and displays the interrupt in the REG0x03[3:0]. Table 18 shows the interrupt register.

The INT_NH is issued if the received noise exceeds the maximum acceptable noise. INT_NH persists until the noise is again back to low.

In case the signal validation block assesses the received signal as disturber, the INT_D is displayed. It is possible to mask the disturber

interrupts INT_D with MASK_DIST (REG0x03[5] =1).

If the MASK_DIST option is enabled, the signal on the pin IRQ never goes high if a disturber is detected.

The interrupt bus IRQ is set back to low whenever the interrupt register is read out.

The AS3935 issues a lightning interrupt (INT_L) if a new event is detected. All new events are stored in the internal memory and build up a

lightning statistic used by the distance estimation algorithm. If the AS3935 issues an interrupt and the Interrupt register is REG0x03[3:0] =000

the distance estimation has changed due to purging of old events in the statistics, based on the lightning distance estimation algorithm.

Whenever an interrupt is issued, the external unit should wait 2ms before reading the Interrupt register.

In addition, it is possible to allow the AS3935 to issue lightning interrupts only if a minimum number of events (lightning) have been detected in

the last 15 minutes. The minimum number of lightning events can be set with register REG0x02[5:4].

When this feature is utilized, a minimum number of events must occur to trigger a valid lightning event. This eliminates false triggers by man-

made disturbers that may pass the validation algorithm. It is possible to clear the statistics built up by the lightning distance estimation algorithm

block by just toggling the bit REG0x02[6] (high-low-high).

011111

31

011011

27

011000

24

010100

20

010001

17

001110

14

001100

12

001010

10

001000

8

000110

6

000101

5

000001

Storm is Overhead

Table 18. Interrupts

Interrupt Name

REG0x03[3:0]

Description

INT_NH

0001

Noise level too high

INT_D

0100

Disturber detected

INT_L

1000

Lightning interrupt

Table 19. Minimum Number of Lightning Detection

Minimum Number of Lightning

REG0x02[5]

REG0x02[4]

10

0

50

1

91

0

16

1

1

Table 17. Distance Estimation

REG0x07[5:0]

Distance [km]