GSM/GPRS Module
M85 Hardware Design
M85_Hardware_Design Confidential / Released 64 / 92
3.13. Behaviors Of The RI
Table 24: Behaviors of the RI
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 44: RI Behavior of Voice Calling as a Receiver
State
RI response
Standby
HIGH
Voicecall
Change to LOW, then:
1. Change to HIGH when call is established.
2. Use ATH to hang up the call, RI changes to HIGH.
3. Calling part hangs up, RI changes to HIGH first, and changes to LOW for
120ms indicating ―NO CARRIER‖ as an URC, then changes to HIGH again.
4. Change to HIGH when SMS is received.
Datacall
Change to LOW, then
:
1. Change to HIGH when data connection is established.
2. Use ATH to hang up the data calling, RI changes to HIGH.
3. Calling part hangs up, RI changes to HIGH first, and changes to LOW for
120ms indicating ―NO CARRIER‖ as an URC, then changes to HIGH again.
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]
Quectel
Confidential