Port A

GPIO Name Peripheral Function Alternate
PA 00

USART

U0_RX  
PA 01

USART

U0_TX  
PA 02

SD and MMC

Card Detect  
PA 03

USART

U0_RTS  
PA 04

USART

U0_CTS  
PA 05

USART

U1_RX  
PA 06

USART

U1_TX  
PA 07

SD and MMC

Write Protect  
PA 08

USART

   
PA 09

USART

U1_CTS  
PA 10

SPI

SPI0_CS0  
PA 11

USB

USB_ID

SPI Interface /SPI0_MISO

PA 12

SPI Interface

SPI0_MOSI  
PA 13

SPI Interface

SPI0_SCK  
PA 14

Dataflash

SPI1_CS0  
PA 15

SPI Interface

SPI1_SCK  
PA 16

SPI Interface

SPI1_SCK  
PA 17

SPI Interface

SPI1_MISO  
PA 18

SD and MMC

SPI1_CS1  
PA 19

LCD

SPI1_CS2  
PA 20

Joystick

EXTINT_8  
PA 21

Temperature Sensor

ADC0  
PA 22

Potentiometer

ADC1  
PA 23

Light Sensor

ADC2  
PA 24

Ethernet

EXTINT_3  
PA 25

Joystick

SCAN_0  
PA 26

Joystick

SCAN_1  
PA 27

Joystick

SCAN_2  
PA 28

Joystick

SCAN_3  
PA 29

TWI

SDA  
PA 30

TWI

SCL