Cinterion
®
Java Terminal Hardware Interface Description
3.8 GPIO Interface
40
PLS62T-W_HID_v01
2018-06-20
Confidential / Prelimenary
Page 32 of 91
3.8.3
SPI Interface
For the Java Terminal four GPIO interface pins can be configured as Serial Peripheral Interface
(SPI). The SPI is a synchronous serial interface for control and data transfer between Java Ter-
minal and the external application. Only one application can be connected to the SPI and the
interface supports only master mode. The transmission rates are up to 6.5Mbit/s. The SPI in-
terface comprises the two data lines MOSI and MISO, the clock line SPI_CLK a well as the chip
select line SPI_CS.
The following pins at the GPIO connector can be configured as SPI interface signals: SPI_CLK,
SPI_MOSI, SPI_MISO and SPI_CS (see also
). The configuration is done by AT com-
mand (see
). It is non-volatile and becomes active after a module restart. For electrical char-
acteristics please refer to
.
To configure and activate the SPI interface use the AT^SSPI command. Detailed information
on the AT^SSPI command as well explanations on the SPI modes required for data transmis-
sion can be found in
. SPI, GPIO and DSR0 functionalities are mutually exclusive.
In general, SPI supports four operation modes. The modes are different in clock phase and
clock polarity. The module’s SPI mode can be configured by using the AT command AT^SSPI.
Make sure the module and the connected slave device works with the same SPI mode.
shows the characteristics of the four SPI modes. The SPI modes 0 and 3 are the most
common used modes.
Figure 8:
Characteristics of SPI modes
SPI MODE 0
SPI MODE 1
SPI MODE 2
SPI MODE 3
Clock phase
C
lock p
o
larity
SPI_CS
MOSI
SPI_CLK
MISO
SPI_CS
MOSI
SPI_CLK
MISO
SPI_CS
MOSI
SPI_CLK
MISO
SPI_CS
MOSI
SPI_CLK
MISO
Sample
Sample
Sample
Sample
