Specifications
LEON-G100/G200 - System Integration Manual
GSM.G1-HW-09002-C Preliminary System description
Page 49 of 75
Ueq
Req
G
gADC
LEON-G100
5
ADC1
Usig
Rsig
Uadc
Ueq
Req
G
gADC
LEON-G100
5
ADC1
Usig
Rsig
Uadc
Figure 34: Equivalent network for ADC single-ended measurement
The LEON-G100 ADC software driver takes care of the parameters shown in Figure 34 (R
eq
, U
eq
, G, g
ADC
). The
voltage measured by the ADC is U
adc
. If the voltage source (U
sig
) has a significant internal resistance (R
sig
)
compared to the input resistance in measurement mode (R
eq
) of the ADC, this should be taken into account and
corrected.
If an external voltage divider is implemented to increase the voltage range, check the input resistance in
measurement mode (R
eq
) of the ADC input and all the electrical characteristics.
The detailed electrical specification of the Analog to Digital Converter input are reported in the
LEON-G100/G200 Data Sheet [1].
1.13 General Purpose Input/Output (GPIO)
LEON-G100/G200 modules provide two General Purpose Input/Output pins (GPIO1, GPIO2) which can be
configured via u-blox AT commands (more details available in u-blox AT Commands Manual [2]).
GPIO2 is dedicated for connection to a u-blox GPS receiver: AT commands are used to drive the GPIO as output
to wake up the u-blox GPS module. If LEON-G100/G200 module is not connected to a u-blox GPS module,
GPIO2 can be used for general purposes.
Unused and unconnected GPIOs should be programmed to a fixed logic level to minimize module idle power
consumption. Therefore set unused pins in GPIO output mode driving ground level.
To avoid an increase of module power consumption any external signal connected to a GPIO must be set
low or tri-stated when the module is in power-down mode. If the external signals in the application circuit
connected to a GPIO cannot be set low or tri-stated, mount a multi channel digital switch (e.g. Texas
Instruments SN74CB3Q16244) or a single channel analog switch (e.g. Texas Instruments TS5A3159 or
TS5A63157) between the two-circuit connections and set to high impedance.
For debug purposes, add a test point on the GPIO1 pin even if this GPIO is not used.