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SA-1110 Developer’s Manual 81
System Control Module
9.1.2 GPIO Alternate Functions
Most GPIO pins have an alternate function that can be invoked to enable additional functionality
within the SA-1110. If a GPIO is used for this alternate function, then it cannot be used as a GPIO
at the same time. Pins 0 and 1 are reserved because of their special use during sleep mode and are
not available for any alternate function. The following table shows each GPIO pin and its
corresponding alternate function. For more details on an alternate function, see the section that
corresponds to its name in the Unit column in the table.
† To enable RCLK_OUT, it is also necessary to set bits [31:29] of the Test Unit Control Register (TUCR) =
0b100. See Appendix D, “Internal Test” for more information about the TUCR.
† The signals, TREQA, TREQB, and TIC_ACK are reserved by Intel for test purposes.
Pin Alternate Function Direction Unit Signal Description
GP 27 32KHZ_OUT
Output Clocks Raw 32.768-kHz oscillator output
GP 26 RCLK_OUT
†
Output Clocks Internal clock/2
GP 25 RTC clock
Output RTC Real time clock
GP 24 Reserved
— — —
GP 23 TREQB
†
Input Test controller TIC request B
GP 22 TREQA
†
/MBREQ Input Test controller Either TIC request A or MBREQ
GP 21 TIC_ACK
†
/MBGNT Output Test controller
Either TIC acknowledge or
MBGNT
GP 21 MCP_CLK
Input Serial port 4 MCP clock in
GP 20 UART_SCLK3
Input Serial port 3:UART Sample clock input
GP 19 SSP_CLK
Input Serial port 4:SSP Sample clock input
GP 18 UART_SCLK1
Input Serial port 1:UART Sample clock input
GP 17 Reserved
— — —
GP 16 GPCLK_OUT
Output Serial port 1 General-purpose clock out
GP 15 UART_RXD
Input Serial port 1:UART UART receive
GP 14 UART_TXD
Output Serial port 1:UART UART transmit
GP 13 SSP_SFRM
Output Serial Port 4:SSP SSP frame clock
GP 12 SSP_SCLK
Output Serial port 4:SSP SSP serial clock
GP 11 SSP_RXD
Input Serial port 4:SSP SSP receive
GP 10 SSP_TXD
Output Serial port 4:SSP SSP transmit
GP 2..9 LDD 8..15
Output LCD controller
High-order data pins for
split-screen color LCD support
GP 1 Reserved
— — No alternate function
GP 0 Reserved
—- — No alternate function