User Guide

GM500-U1G_A

Hardware Development Guide

2.13. ADC Interface

The module provides 3 ADCs to digitize the analog signal to 15-bit digital data such as battery voltage, temperature and so on.

Using AT commandcan read the voltage value on ADC pin. The read value is expressed in mV. For more details of these AT commands,

please refer to document [AT Command Reference Guide of Module Product GM500-U1G_A].

In order to improve the accuracy of ADC, the trace of ADC should be surrounded by ground.

Table 2-17 Pin Definition of the ADC

Pin Name Pin NO. Description

ADC1 48 General purpose analog to digital converter.

ADC2 47 General purpose analog to digital converter.

ADC3 108 General purpose analog to digital converter.

The following table describes the characteristic of the ADC function.

Table 2-18 Characteristic of the ADC

Item Min Max Unit

ADC1 voltage range 0.05 4.15 V

ADC2 voltage range 0.05 4.15 V

ADC3 voltage range 0.05 4.15 V

ADC internal structure is shown in the figure below. It can be seen that after each ADC pin inputs the module, there are two

conversion channels. You can select 1 / 3

scaling

channel to do ADC conversion, or directly send it to ADC converter. Since the internal

reference voltage is 1.8V, the user can determine the channel according to the external voltage range to be converted. The channel

selection can be programmed or customized by users 1 / 3 ADC channel configuration by default.

Figure 2–29 ADC internal structure

Table 2-19ADCinterface features(1/3 scaling)

Item VIN Min(V) VIN Max(V) ADC channel

configuration

Minimum input

resistance(MΩ)

Maximum

input current

ADC1 0.3 VBAT 1/3 1M 100 nA

ADC2 0.3 VBAT 1/3 1M 100 nA