muxed
-0 uart0_tx spi0_sclk
-1 uart0_rx spi0_mosi
-2 spi0_ss uart0_rx
-3 uart1_tx spi0_miso
+0 uart0_tx spi0_sclk uart2_tx uart3_tx
+1 uart0_rx spi0_mosi uart2_rx uart3_rx
+2 twi0_sda spi0_ss
+3 twi0_scl spi0_miso
+8 sd0_clk sd1_clk
+9 sd0_cmd sd1_cmd
+10 sd0_d0 sd1_d0
+11 sd0_d1 sd1_d1
+12 sd0_d2 sd1_d2
+13 sd0_d3 sd1_d3
+dedicated
+4 uart1_tx
+5 uart1_rx
+6 twi1_sda
+7 twi1_scl