3 Application Interfaces
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◦ RF coupling will cause interference to GND. Adjust the capacitance values of capacitor
and ESD components or even remove the capacitor (if it is necessary) to avoid the
interference.
⚫ PCB crosstalk:
Reason:
◦ Other signal line on the main board has crosstalk with the SIM signal through the PCB
routing.
◦ Antenna interrupted signal has crosstalk with the SIM signal through the PCB routing.
◦ Fluctuations of power has crosstalk with the SIM signal through the PCB routing.
◦ Adjust the filter capacitance value the of SIM signal.
◦ Find out the interference source, and change the board specifically.
3.3.6 ADC
Background
An analog-to-digital converter (ADC) converts analog signals into digital values for use in
processing and control systems. It can be used for voltage detection and other external
circuits.
Schematic Diagram Design
The module provides two ADC interfaces, send the AT+MMAD=<INDEX> command (INDEX
is the ADC channel) can read the voltage value of the channel. The ADC voltage ranges from
0 to VBAT, with 12-bit resolution and sampling accuracy from 20mV to 50mV. When using the
ADC function, it is recommended to connect a 1KΩ resistor in serial mode to enhance ESD
protection.
PCB Design
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