Users Manual

GSM/GPRS Module Series
M66 Hardware Design
M66_Hardware_Design Confidential / Released 57 / 82
SD_DATA, SD_CMD and SD_CLK to be less than 10mm.
 In order to offer good ESD protection, it is recommended to add TVS on signals with capacitance less
than 15pF.
 Reserve external pull-up resistors for other data lines except the DATA0 signal.
 The SD_CLK and SD_DATA line must be shielded by ground in order to improve EMI suppression
capability.
3.12. 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 19: Pin Definition of the ADC
Table 20: Characteristics of the ADC
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