I 2 S A u d i o I / O C a r d
8
Rev. 0.1
4.5.2. Joystick Switch
The I/O card has a five-position joystick switch (S1) that connects to the co-processor C8051F380 MCU. The
joystick is normally open and pulls a signal voltage to ground when the joystick is placed in one of the five
positions. Table 4 show the co-processor port pin connections to the joystick.
4.6. SD Card Connector (U10)
The SD card connector (U10) connects to any standard SD card. The card power from PWR_3.3_BULK can be
enabled or disabled by the SPI_PWR signal connected to GPIO03.
The connector includes two mechanical switches: one detects if a card is inserted, and one indicates the write
protection status of the card. The card detection switch connects to the GPIO04 signal. The JP3 header provides
access to both the switch signals.
4.7. EBID MCU (U11)
The I/O card has a unique ID that can be read out from the Silicon Labs C8051F990 MCU (U11). This MCU
enables software tools to recognize the connected hardware and automatically select the appropriate firmware
image.
Table 4. Joystick Switch Connections
Joystick Position
Co-processor Pin
Center
P0.6
Up
P0.2
Down
P0.3
Left
P0.4
Right
P0.5
