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Intel® PXA255 Processor Developer’s Manual 4-3
System Integration Unit
For more information on alternate functions, refer to the Source Unit column in Table 4-1 for the
appropriate section of this document.
Table 4-1. GPIO Alternate Functions (Sheet 1 of 4)
Pin
Alternate
Function Name
Alternate Function
Assignment
AF{n}
encoding
Source Unit Signal Description and comments
GP1 GP_RST ALT_FN_1_IN 01
Clocks & Power
Manager Unit
Active low GP_reset
GP6 MMCCLK ALT_FN_1_OUT 01
Multimedia Card
(MMC) Controller
MMC Clock
GP7 48 MHz clock
†
ALT_FN_1_OUT 01
Clocks & Power
Manager Unit
48 MHz clock output
GP8 MMCCS0 ALT_FN_1_OUT 01
Multimedia Card
(MMC) Controller
MMC Chip Select 0
GP9 MMCCS1 ALT_FN_1_OUT 01 MMC Chip Select 1
GP10 RTCCLK ALT_FN_1_OUT 01
System Integation
Unit
real time clock (1 Hz)
GP11 3.6 MHz ALT_FN_1_OUT 01
Clocks & Power
Manager Unit
3.6 MHz oscillator out
GP12 32 kHz ALT_FN_1_OUT 01 32 kHz out
GP13 MBGNT ALT_FN_2_OUT 10
Memory Controller
memory controller grant
GP14 MBREQ ALT_FN_1_IN 01
memory controller alternate bus
master request
GP15 nCS_1 ALT_FN_2_OUT
10 Active low chip select 1
GP16 PWM0 ALT_FN_2_OUT
10 PWM0 output
GP17 PWM1 ALT_FN_2_OUT
10 PWM1 output
GP18 RDY ALT_FN_1_IN
01 Ext. Bus Ready
GP19 DREQ[1] ALT_FN_1_IN 01 External DMA Request
GP20 DREQ[0] ALT_FN_1_IN 01 External DMA Request
GP23
SCLK ALT_FN_2_OUT 10
SSP Serial Port
SSP clock
GP24
SFRM ALT_FN_2_OUT 10 SSP Frame
GP25
TXD ALT_FN_2_OUT 10 SSP transmit
GP26 RXD ALT_FN_1_IN 01
SSP receive
GP27 EXTCLK ALT_FN_1_IN
01 SSP ext_clk
GP28
BITCLK ALT_FN_1_IN
01 AC97 Controller Unit AC97 bit_clk
BITCLK ALT_FN_2_IN
10
I2S Controller
I2S bit_clk
BITCLK ALT_FN_1_OUT 01 I2S bit_clk
GP29
SDATA_IN0 ALT_FN_1_IN
01 AC97 Controller Unit AC97 Sdata_in0
SDATA_IN ALT_FN_2_IN 10 I2S Controller I2S Sdata_in
GP30
SDATA_OUT ALT_FN_1_OUT 01 I2S Controller I2S Sdata_out
SDATA_OUT ALT_FN_2_OUT 10 AC97 Controller Unit AC97 Sdata_out
GP31
SYNC ALT_FN_1_OUT 01 I2S Controller I2S sync
SYNC ALT_FN_2_OUT 10 AC97 Controller Unit AC97 sync
GP32
SDATA_IN1 ALT_FN_1_IN
01 AC97 Controller Unit AC97 Sdata_in1
SYSCLK ALT_FN_1_OUT 01 I2S Controller I2S System Clock