M50 Hardware Design
M50_HD_V2.0
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4. Change to HIGH when SMS is received.
SMS
When a new SMS comes, the RI changes to LOW and holds low level for
about 120 ms, then changes to HIGH.
URC
Certain URCs can trigger 120ms low level on RI. For more details, please
refer to the
document [1]
If the module is used as a caller, the RI would maintain high except the URC or SMS is received.
On the other hand, when it is used as a receiver, the timing of the RI is shown below.
RI
Idle
Ring
Off-hook by
“
ATA
”
On-hook by
“
ATH
”
SMS received
HIGH
LOW
Figure 43
: RI behavior of voice calling as a receiver
RI
Idle
Ring
Data calling establish
SMS received
HIGH
LOW
On-hook by
“
ATH
”
Figure 44
: RI behavior of data calling as a receiver
RI
Idle
Calling
On-hook
Talking
HIGH
LOW
Idle
Figure 45
: RI behavior as a caller
Quecctel
Confidential