User's Manual l MBa57xx UM 0100 l © 2020, TQ-Systems GmbH
Page 14
4.1.5
Port Expander
Two PCA9555PW port expanders with 16 ports each are used to control several components on the MBa57xx. These include the
buzzer, user LEDs, user GPIOs, configuration signals for mPCIe and push buttons.
The port expanders are configured via I2C4. The expander addresses can be changed by rearranging resistors. When changing
the address, care must be taken to avoid address conflicts with existing I
2
C devices. The assembly options are documented in the
MBa57xx circuit diagram. In the initial state after power-on all ports are set as input.
Illustration 4:
Block diagram port expander D22 and D23
The following tables show details of port expanders.
Table 11:
Functions of port expanders
Port Expander
Port
Signal
Dir.
Remark
Port Expander I, D22
IO0_0
BOOT_CFG_EN#
O
Enable Boot Config on carrier board
IO0_1
BUTTON_1#
I
Push button
IO0_2
BUTTON_2#
I
Push button
IO0_3
BUTTON_3#
I
Push button
IO0_4
LCD_EN
O
Enable LCD (X56)
IO0_5
USB3.0_H3_OTG_ID
I
USB-ID for OTG
IO0_6
PR2_MII0_RST
O
10/100 Base Ethernet reset
IO0_7
PR2_MII1_RST
O
10/100 Base Ethernet reset
IO1_0
RGMII0_INT#
I
Gbit Ethernet INT/PWDN
IO1_1
RGMII1_INT#
I
Gbit Ethernet INT/PWDN
IO1_2
PCIE_WAKE#
O
Wake signal for PCIe and mPCIe
IO1_3
PCIE_DIS#
O
Disable signal for PCIe and mPCIe
IO1_4
LCD_PWR_EN
O
LCD Power Enable
IO1_5
LCD_BLT_EN
O
LCD Backlight Enable
IO1_6
PWR_EN_3V3_DISPLAY
O
Enable 3.3 V display supply
IO1_7
LVDS_EN
O
Enable LCD (X54)
Port Expander II, D23
IO0_0
BUZZER_PWM
O
Unused – GPIO6_19_B26 of TQMa57xx is used
IO0_1
PWR_EN_1V5
O
–
IO0_2
PWR_EN_1V1
O
–
IO0_3
LED0
O
–
IO0_4
LED1
O
–
IO0_5
GPIO_EXP_IO5
O
Optional: audio reset
IO0_6
GPIO_EXP_IO6
O
Optional: mPCIe reset
IO0_7
GPIO_EXP_IO7
O
Optional: LCD reset
IO1_0
PR2_MII0_INT#
I
10/100 Base Ethernet Interrupt
IO1_1
PR2_MII1_INT#
I
10/100 Base Ethernet Interrupt
IO1_2
RGMII0_RST#
O
Gbit Ethernet reset
IO1_3
RGMII1_RST#
O
Gbit Ethernet reset
IO1_4
USB2.0_HUB_RST#
O
–
IO1_5
USB3.0_HUB_RST#
O
–
IO1_6
PCIE_RST#
O
PCIe reset
IO1_7
SATA_M2_RST#
O
SATA reset
