Technical information

A/D Interface
42 G30 - Module Hardware Description December 15, 2009
A/D Interface
The G30 includes 3 Analog to Digital Converter (ADC) signals with 12-bit resolution, for
environmental and electrical measurements. The ADC signals measure an analog DC voltage
level on their inputs which is converted to a 12-bit digital value for further processing by G30 or
the user application.
The A/D signals operation and reporting mechanism is defined by the AT+MADCM command.
Each A/D can be defined to provide several reports:
• A single measurement.
A single A/D measurement will take place and will be reported upon activation of the AT
command.
• An automatic periodical measurement.
The A/D measures its input signal at a rate that is defined by the user application. Every
measurement will generate an unsolicited message over the serial interface.
• An automatic periodical measurement with predefined limits.
The A/D measures its input signal at a rate that is defined by the user. The user also defines
upper and/or lower limits for the A/D measurements. Each measurement is compared to
these limits, and an unsolicited message is generated only if these limits are exceeded.
Important: In case the defined periodical measurement rate is equal to, or shorter than, the
defined sleep mode delay settings (ATS24), G30 will not enter low power mode.
Important: Applying voltage to ADC lines before power up is forbidden and may cause G30
power up issues.
Important: If some ADC signals are not used, a 47 kOhm pull-down resistor to GND must be
connected for each of the unused ADC lines.
Power Supply A/D
The main power supply (VCC) is constantly monitored internally by the G30 through a dedicated
A/D signal, which is not accessible on the interface connector.
The measured VCC level can be read and monitored by the user application through the
AT+MADCM command, which returns the measured VCC level in Volts times 1000.
For example, a measured supply level of 3.65 Volts will be presented as 3650 by the MADCM
command.