M20 Hardware Design
If the module is used as a caller, the RI0 would maintain high. On the other hand, when it is used
as a receiver, the timing of the RI0 is shown below.
RI0
Idle
Ring
Off-hook by
“
ATA
”
. On-hook
by
“
ATH
”
. Calling
party on-hook. SMS
received.
HIGH
LOW
Figure 37
: RI0 behaviour of voice calling as a receiver
RI0
Idle
Ring
Enter GPRS Ready
Mode. On-hook by
“
ATH
”
.
HIGH
LOW
Figure 38
: RI0 behaviour of data calling as a receiver
RI0
Idle
Calling
On-hook
Talking
HIGH
LOW
SMS received
Idle
Figure 39
: RI0 behaviour of data calling as a caller
M20_HD_V1.01
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