GSM/GPRS Module Series
M66 Hardware Design
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3.11. ADC
The module provides an ADC channel to measure the value of voltage. Please give priority to the use of
ADC0 channel. The command
AT+QADC
can read the voltage value applied on ADC0 pin. For details of
this AT command, please refer to the
document [1]
.
In order to improve the accuracy of ADC, the layout
of ADC should be surrounded by ground.
Table 17: Pin Definition of the ADC
Table 18: Characteristics of the ADC
3.12. Behaviors of The RI
Table 19: Behaviors of the RI
Pin Name
Pin No.
Description
AVDD
8
Reference voltage of ADC circuit
ADC0
9
Analog to digital converter.
Item
Min.
Typ.
Max.
Units
Voltage Range
0
2.8
V
ADC Resolution
10
bits
ADC Accuracy
2.7
mV
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.
SMS
When a new SMS comes, the RI changes to LOW and holds low level for about
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