Maxim Integrated 73M1866B/73M1966B Implementers Guide User Manual
Page 21
UG_1x66B_016
73M1866B/73M1966B Implementer’s Guide
Rev. 1.3
21
The registers used for Ring Detection and Line Voltage Reversal are:
0x05
ENGPIO7 ENGPIO6 ENGPIO5 ENPCLKDT ENAPOL
ENDET
ENSYNL ENRGDT
Write
X
X
X
X
X
X
X
1
0x0E
FRCVCO
Res
Res
Res
Res
Res
RGTH1
RGTH0
Write
X
X
X
X
X
X
Threshold
0x03
GPIO7
GPIO6
GPIO5
PCLKDT
RGMON
DET
SYNL
RGDT
Write
X
X
X
X
X
X
X
?
Set the ring detect threshold voltage
Set ENRGT = 1 in Register 0x05 to enable the RGMON and RGDT interrupts. See
Section
(Threshold) in the RGTH[1:0] bits in Register 0x0E.
for more information on interrupts.
The system variables defined in this procedure are:
ring_count
= initial 0, keeps track of number of ring
interrupts
ring_first
= time of first ring interrupt
ring_last
= time of last ring interrupt
ring_frequency = ring frequency in HZ
ring_duration = ring duration
Begin @ RGDT interrupt (RGDT = 1)
1. If (ring_count == 0) ring_first = now;
2. ring_last = now
3. start/restart ring_timer for approx 150 ms
End
Begin @ ring_timer expire
1. If (ring_last - ring_first) < 150 ms Polarity Reversal Event
2. Else Ring Burst
a. ring_duration = ring_last – ring_first
b. ring_frequency – 2* ring_count / ring_duration)
End
1
The ring detect threshold is country specific. The recommended values are shown in the 73M1x66
Worldwide Design Guide.
@RGDT
If(ring_count == 0)
Ring_last = now
Ring_count++
Restart
ring_timer
End
If(ring_count == 0)
ring_first = now
@ ring_timer
expires
If(ring_last –
ring_first) <
150ms
RING_BURST
End
Polarity
Reversal
TRUE