User's Manual l MBa7x UM 0101 l © 2020, TQ-Systems GmbH
Page 17
4.1.5
Port Expander
The 16-port port expander PCA9555 is used to control several components on the MBa7x. These include the alarm buzzer, User
LEDs, User GPIOs, configuration signals for Mini PCIe and navigation buttons.
The port expander is configured via I2C2. The sensor address can be changed by reassembling resistors. When changing the
address, care must be taken to avoid address conflicts with existing I
2
C devices. In the initial state after power-on, all ports are set
as input and the connected component is thus deactivated.
The following tables show details of port expander D2100.
Table 14:
Functions of port expander D2100
Port
Signal
Dir.
Default
Remark
IO0_0
BUZZER
O
Low
Buzzer On / Off
IO0_1
LVDS_SHDN#
O
High
Enable for LVDS transceiver SN75LVD
IO0_2
SC_MOD_VCC
O
Low
Supply voltage 1.8 V / 3 V for Smart card (X6)
IO0_3
PE_GPIO3
I/O
High
GPIO3 at X25-40
IO0_4
PE_GPIO4
I/O
High
GPIO4 at X25-42
IO0_5
PE_GPIO5
I/O
High
GPIO5 at X25-44
IO0_6
PE_GPIO6
I/O
High
GPIO6 at X25-46
IO0_7
PE_GPIO7
I/O
High
NC (only routed to test point TP2132 on MBa7x)
IO1_0
LED1
O
Low
Green LED On / Off
IO1_1
LED2
O
Low
Green LED On / Off
IO1_2
VCC3V3_MPCIE_EN
O
Low
Enable-Signal for 3.3 V PCIe supply voltage
IO1_3
VCC12V_EN
O
Low
Enable-Signal for 12 V supply voltage
IO1_4
VCC1V5_MPCIE_EN
O
Low
Enable-Signal for 1.5 V PCIe supply voltage
IO1_5
SWITCH_A#
I
High
Input for navigation push button “A“
IO1_6
SWITCH_B#
I
High
Input for navigation push button “B“
IO1_7
SWITCH_C#
I
High
Input for navigation push button “C”
Figure 6:
Position of port expander D2100
7:
Planned port configuration.
8:
Initial state for Off/Inactive mode.
