User's Manual

UE866 HARDWARE USER GUIDE 1vv0301157 Rev.7 • 2015-04-17 40 of 68
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Also the UART’s control flow pins can be usable as GPIO:
PAD
Signal
I/O
Input/output
current
Default
State
ON_OFF
state
Reset
State
NOTE
B2
GPO_A
O
1uA/1mA
INPUT
0
0
Alternate function
C109/DCD
B3
GPO_B
O
1uA/1mA
INPUT
0
0
Alternate function
C125/RING
A3
GPO_C
O
1uA/1mA
INPUT
0
0
Alternate function
C107/DSR
A2
GPI_E
I
1uA/1mA
INPUT
0
0
Alternate function
C108/DTR
A1
GPI_F
I
1uA/1mA
INPUT
0
0
Alternate function
C105/RTS
B1
GPO_D
O
1uA/1mA
INPUT
0
0
Alternate function
C106/CTS
Using a GPIO as INPUT
The GPIO pads, when used as inputs, can be connected to a digital output of another device and
report its status, provided this device has interface levels compatible with the 1.8V CMOS levels of the
GPIO.
If the digital output of the device to be connected with the GPIO input pad has interface levels different
from the 1.8V CMOS, then it can be buffered with an open collector transistor with a 47K pull up to
1.8V.
NOTE:
In order to avoid a back powering effect it is recommended to avoid having any
HIGH logic level signal applied to the digital pins of the UE866 when the
module is powered off or during an ON/OFF transition.
The V_AUX / PWRMON pin can be used for input pull up reference or/and for
ON monitoring.
Using a GPIO as OUTPUT
The GPIO pads, when used as outputs, can drive 1.8V CMOS digital devices or compatible hardware.
When set as outputs, the pads have a push-pull output and therefore the pull-up resistor may be
omitted.