Chapter 3 – Electrical Characteristics
Multi-Tech Systems, Inc. MMCModem GPRS Developer’s Guide (S000445D)
20
Flashing LED Electrical Interface
The flashing LED signal is used to indicate the working mode of the MMCModem.
Flashing LED Pin Description
Signal
Pin #
I/O
I/O Type*
Description
Flashing LED 11
I/O
CMOS/2X
Working mode indication LED
* See “Operating Conditions” in section on the 50-pin Connector Description.
General Purpose Input/Output Electrical Interface
The MMCModem provides two General Purpose I/O connections. They can be used to
control any external device.
General Purpose I/O Pin Description
Signal
Pin #
I/O
I/O Type*
Description
Default Value
GPIO0
26
I/O
CMOS / 2X
General Purpose I/O
0
GPIO4
7
I/O
CMOS / 2X
General Purpose I/O
0
* See “Operating Conditions” in section on the 50-pin Connector Description.
All digital I/O complies with 3Volts CMOS.
You can access (write or read) the GPIO value via AT+WIOW and AT+WIOR. See AT
Command manual for more details.
Analog to Digital Converter Electrical Interface
The MMCModem has an Analog to Digital converter (ADC) input. This converter is 10 bits,
ranging from 0 to 2.5V. You can see the measurements via AT+ADC. See AT Command
manual for more details.
A/D Converter Pin Description
Signal
Pin #
I/O
I/O Type*
Description
AUXV0 17 I
Analog
A/D
converter
* See “Operating Conditions” in section on the 50-pin Connector Description.
A/D Converter Electrical Characteristics
Parameter
Min
Max
Unit
Resolution 10
bits
Sampling Rate
90.3
Ksps
Input Signal Range
0
2.5V
Volts
ADC Reference Accuracy
0.5
%
Integral Accuracy
+/- 1
LSB
Differential Accuracy
+/- 1
LSB
Input Impedance ( R )
10
meg-Ohms
Input Impedance ( C )
50
pico-Farads
