GP0 1 General IO / SPI0 RX / I2C0 SDA / UART0 TX GP1 2 General IO / SPI0 CSn / I2C0 SCL / UART0 RX GP2 4 General IO / SPI0 SCK / I2C1 SDA GP3 5 General IO / SPI0 TX / I2C1 SCL GP6 9 General IO / SPI0 ...