Cinterion
®
Java Terminal Hardware Interface Description
8.5 Configuring GPIO Directions
90
PLS62T-W_HID_v01
2018-06-20
Confidential / Prelimenary
Page 81 of 91
8.5
Configuring GPIO Directions
As already shown in
the GPIO pins at the Java Ter-
minal‘ GPIO connector are not electrically identical to the GPIO lines at the integrated Java
module. A built-in level shifter needs to ensure that the voltage level is correctly converted.
Because of that it is necessary to not only configure the Java modules‘ GPIO settings by AT
command, but to also configure the the built-in level shifter‘s GPIO directions by means of the
watchdog.
As described in
and shown in
there are various ways to con-
figure the watchdog and therefore the level shifter‘s GPIO directions:
•
A qualified configuration including GPIO directions can be done using the watchdog‘s I
2
C
interface. For details see
. This is the recommended method to set the level
shifter‘s GPIO direction.
•
A complete configuration can be done using the TXD0 line of the ASC0 interface. For
details see
.
Notes: The VCCref signal at the Java Terminal‘s GPIO connector needs to be connected - for
instance to the +5Vout signal - for the level shifters to be active. Also note that in order to have
a defined level for GPIOs configured as inputs, external pull-ups or pull-downs will have to be
implemented at the GPIO lines.
