Motorola G24 - General Purpose A;D

Chapter 2: Hardware Interface Description
January 1, 2006 Module Hardware Description 43
General Purpose A/D
The G24 provides 3 general purpose A/D (GPAD) signals for customer application use. Each
A/D signal can monitor a separate external voltage and report its measured level independently to
the application, through the AT command interface.
The GPAD signals can sense a DC voltage level of 0 - 2.3 V, which is converted internally to a
10-bit digital value. The A/D input is sampled 8 consecutive times for each measurement, and the
8 samples are compared and averaged to provide a stable and valid result.
The A/D signals operation and reporting mechanism is defined by the AT+MMAD 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.
Important: In case the defined periodical measurement rate is equal to, or shorter than, the
defined sleep mode delay settings (ATS24), G24 will not enter low power mode.
• 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), G24 will not enter low power mode.
Table 2-19 gives the GPAD specifications.
Table 2-19:
GPAD Specifications
Parameter Conditions Min Typ Max Unit
Maximum
Input Voltage
Operating range -0.1 2.75 V
Input Voltage Dynamic range 2.3 V
Sampling
Time
8 consecutive
samples
100 µS
Resolution 10 mV