Hardware layout and configuration UM1855
48/100 DocID027351 Rev 3
2.26.1 Limitations
Touch sensing button is exclusive with LCD glass module, thermal sensor PT100 via sigma-
delta conversion, USB OTG FS port operating as USB host, SWP and NFC.
2.27 Smartcard, SWP
ST8024CDR, an interface device for 3 V and 5 V asynchronous smartcards, is fitted on the
STM32L476G-EVAL main board, in U30 position. ST8024CDR performs all supply
protection and control functions of the smartcard.
ST8024CDR is controlled, on its turn, by STM32L476ZGT6, directly through its ports or
indirectly through ports of the U33 I/O expander device (IOExpander2), as shown in
Table 28.
The SWIO port of the smartcard for single-wire protocol (SWP) communication is managed
directly by PB12 port of STM32L476ZGT6.
Table 29 provides information on configuration elements related with smartcard operation.
Refer to Table 8, Table 12,Table 26 andTable 27 for complementary information. Bridging of
CN11 and CN14 rows of I/Os can be done by means of the MB979 daughterboard plugged
into CN11 and CN14 in I/O-bridge position, as explained in Section 2.15.
SB30
Open
Default setting. PC7 port of STM32L476ZGT6 is not routed to motor
control.
This setting is good for robustness of touch sensing.
Closed
PC7 is routed to motor control. This setting is not good for robustness
of touch sensing.
Table 27. Touch-sensing-related configuration elements (continued)
Element Setting Configuration
Table 28. Assignment of ports for ST8024CDR control
ST8024CDR
port
Function Control port
5V/3V Smartcard power supply selection pin. IOexpander2 GPIO7
I/OUC Data I/O line STM32L476ZGT6 PC4
XTAL1 Quartz crystal or external clock input STM32L476ZGT6 PB0
OFF Card presence detect IOexpander2 GPIO8
RSTIN Card reset command input IOexpander2 GPIO5
CMDVCC Activation sequence start command input (active low) IOexpander2 GPIO6
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