Este artículo explica cómo usar múltiples puertos UART en ODROID-C2 con el sistema operativo Android. Utilizaremos 3 puertos UART y crearemos un flujo de datos llamado Daisy Chain. El flujo de datos básico parte desde TX del UART 1 hacia el RX del UART 2 y luego va a TX UART 2, que enviará los datos a RX del UART 3. Una vez que RX del UART 3 recibe los datos, lo envía desde 7. Para esto, necesitas utilizar la última versión de Android 6.0.1 versión 3.6 o superior y así poder usar 3 puertos UART de forma simultánea.
Hardware
Antes de empezar, tienes que hacerte con algunas cosas. Primero, descarga el diagrama Fritzing desde https://goo.gl/Q1YhP3. Comprueba el diseño de los pines J2 2×20 en https://goo.gl/44XGpB.
PUERTO |
PIN |
|
TX |
RX |
|
| UART_A (ttyS1) | 8 | 10 |
| UART_B (ttyS2) | 3 | 5 |
| UART_C (ttyS3) | 32 | 26 |
Software
Necesitas modificar el archivo de Árbol del Dispositivos para habilitar UART_B (ttyS2) y UART_C (ttyS3) ya que Android los usa para otros fines, como GPIO/I2C.
Deshabilitar I2C
$ diff --git a/arch/arm64/boot/dts/meson64_odroidc2.dts b/arch/arm64/boot/dts/meson64_odroidc2.dts
index e6a25b0..db09b04 100755
--- a/arch/arm64/boot/dts/meson64_odroidc2.dts
+++ b/arch/arm64/boot/dts/meson64_odroidc2.dts
@@ -813,18 +813,6 @@
};
-&i2c_a {
- status = "okay";
-
- /* Hardkernel I2C RTC */
- pcf8563: pcf8563@51 {
- status = "disabled";
- compatible = "nxp,pcf8563";
- reg = <0x51>;
- #clock-cells = <0>;
- };
-};
-
&i2c_b {
status = "okay";
Añadir las definiciones UART_B y UART_C
El archivo kernel/arch/arm64/boot/dts/meson64_odroidc2.dts se puede descargar desde https://goo.gl/Y7c5Wr, tal y como se muestra a continuación:
$ diff --git a/arch/arm64/boot/dts/meson64_odroidc2.dts b/arch/arm64/boot/dts/meson64_odroidc2.dts
index e6a25b0..fd41552 100755
--- a/arch/arm64/boot/dts/meson64_odroidc2.dts
+++ b/arch/arm64/boot/dts/meson64_odroidc2.dts
@@ -31,6 +31,8 @@
aliases {
serial0 = &uart_AO;
serial1 = &uart_A;
+ serial2 = &uart_B;
+ serial3 = &uart_C;
};
gpu_dvfs_tbl: gpu_dvfs_tbl {
@@ -459,6 +461,32 @@
pinctrl-0 = <&a_uart_pins>;
};
+ uart_B: serial@c11084dc {
+ compatible = "amlogic, meson-uart";
+ reg = <0x0 0xc11084dc 0x0 0x18>;
+ interrupts = <0 75 1>;
+ status = "okay";
+ clocks = <&clock CLK_XTAL>;
+ clock-names = "clk_uart";
+ fifosize = < 64 >;
+ pinctrl-names = "default";
+ pinctrl-0 = <&b_uart_pins>;
+ resets = <&clock GCLK_IDX_UART1>;
+ };
+
+ uart_C: serial@c1108700 {
+ compatible = "amlogic, meson-uart";
+ reg = <0x0 0xc1108700 0x0 0x14>;
+ interrupts = <0 93 1>;
+ status = "okay";
+ clocks = <&clock CLK_XTAL>;
+ clock-names = "clk_uart";
+ fifosize = < 64 >;
+ pinctrl-names = "default";
+ pinctrl-0 = <&c_uart_pins>;
+ resets = <&clock GCLK_IDX_UART2>;
+ };
+
canvas {
compatible = "amlogic, meson, canvas";
dev_name = "amlogic-canvas";
Compilar dts hacia dtb
El archivo Meson64_odroidc2.dtd se puede descargar desde https://goo.gl/qha1vx, tal y como se muestra a continuación:
$ make odroidc2_[i2c_]defconfig KBUILD_CFLAGS_MODULE:-DMODULE # # configuration written to .config # #### make completed successfully #### [~/projects/c2/marshmallow/kernel]$ make dtbs KBUILD_CFLAGS_MODULE:-DMODULE KBUILD_CFLAGS_MODULE:-DMODULE scripts/kconfig/conf --silentoldconfig Kconfig KBUILD_CFLAGS_MODULE:-DMODULE WRAP arch/arm64/include/generated/asm/bug.h WRAP arch/arm64/include/generated/asm/bugs.h WRAP arch/arm64/include/generated/asm/checksum.h WRAP arch/arm64/include/generated/asm/clkdev.h WRAP arch/arm64/include/generated/asm/cputime.h WRAP arch/arm64/include/generated/asm/current.h WRAP arch/arm64/include/generated/asm/delay.h WRAP arch/arm64/include/generated/asm/div64.h WRAP arch/arm64/include/generated/asm/dma.h WRAP arch/arm64/include/generated/asm/emergency-restart.h WRAP arch/arm64/include/generated/asm/early_ioremap.h WRAP arch/arm64/include/generated/asm/errno.h WRAP arch/arm64/include/generated/asm/ftrace.h WRAP arch/arm64/include/generated/asm/hw_irq.h WRAP arch/arm64/include/generated/asm/ioctl.h WRAP arch/arm64/include/generated/asm/ioctls.h WRAP arch/arm64/include/generated/asm/ipcbuf.h WRAP arch/arm64/include/generated/asm/irq_regs.h WRAP arch/arm64/include/generated/asm/kdebug.h WRAP arch/arm64/include/generated/asm/kmap_types.h WRAP arch/arm64/include/generated/asm/kvm_para.h WRAP arch/arm64/include/generated/asm/local.h WRAP arch/arm64/include/generated/asm/local64.h WRAP arch/arm64/include/generated/asm/mman.h WRAP arch/arm64/include/generated/asm/msgbuf.h WRAP arch/arm64/include/generated/asm/mutex.h WRAP arch/arm64/include/generated/asm/pci.h WRAP arch/arm64/include/generated/asm/poll.h WRAP arch/arm64/include/generated/asm/posix_types.h WRAP arch/arm64/include/generated/asm/resource.h WRAP arch/arm64/include/generated/asm/scatterlist.h WRAP arch/arm64/include/generated/asm/sections.h WRAP arch/arm64/include/generated/asm/segment.h WRAP arch/arm64/include/generated/asm/sembuf.h WRAP arch/arm64/include/generated/asm/serial.h WRAP arch/arm64/include/generated/asm/shmbuf.h WRAP arch/arm64/include/generated/asm/simd.h WRAP arch/arm64/include/generated/asm/sizes.h WRAP arch/arm64/include/generated/asm/socket.h WRAP arch/arm64/include/generated/asm/sockios.h WRAP arch/arm64/include/generated/asm/switch_to.h WRAP arch/arm64/include/generated/asm/swab.h WRAP arch/arm64/include/generated/asm/termbits.h WRAP arch/arm64/include/generated/asm/termios.h WRAP arch/arm64/include/generated/asm/topology.h WRAP arch/arm64/include/generated/asm/trace_clock.h WRAP arch/arm64/include/generated/asm/types.h WRAP arch/arm64/include/generated/asm/unaligned.h WRAP arch/arm64/include/generated/asm/user.h WRAP arch/arm64/include/generated/asm/vga.h WRAP arch/arm64/include/generated/asm/xor.h WRAP arch/arm64/include/generated/asm/preempt.h WRAP arch/arm64/include/generated/asm/hash.h WRAP arch/arm64/include/generated/uapi/asm/kvm_para.h HOSTCC scripts/dtc/checks.o HOSTCC scripts/dtc/data.o SHIPPED scripts/dtc/dtc-lexer.lex.c SHIPPED scripts/dtc/dtc-parser.tab.h HOSTCC scripts/dtc/dtc-lexer.lex.o SHIPPED scripts/dtc/dtc-parser.tab.c HOSTCC scripts/dtc/dtc-parser.tab.o HOSTCC scripts/dtc/dtc.o HOSTCC scripts/dtc/flattree.o HOSTCC scripts/dtc/fstree.o HOSTCC scripts/dtc/livetree.o HOSTCC scripts/dtc/srcpos.o HOSTCC scripts/dtc/treesource.o HOSTCC scripts/dtc/util.o HOSTLD scripts/dtc/dtc CC scripts/mod/empty.o HOSTCC scripts/mod/mk_elfconfig MKELF scripts/mod/elfconfig.h CC scripts/mod/devicetable-offsets.s GEN scripts/mod/devicetable-offsets.h HOSTCC scripts/mod/file2alias.o HOSTCC scripts/mod/modpost.o HOSTCC scripts/mod/sumversion.o HOSTLD scripts/mod/modpost HOSTCC scripts/selinux/genheaders/genheaders HOSTCC scripts/selinux/mdp/mdp HOSTCC scripts/kallsyms HOSTCC scripts/pnmtologo HOSTCC scripts/conmakehash HOSTCC scripts/bin2c HOSTCC scripts/recordmcount HOSTCC scripts/sortextable DTC arch/arm64/boot/dts/meson64_odroidc2.dtb Warning (reg_format): "reg" property in /spi-gpio/spi-gpio@0 has invalid length (4 bytes) (#address-cells == 2, #size-cells == 1) Warning (avoid_default_addr_size): Relying on default #address-cells value for /spi-gpio/spi-gpio@0 Warning (avoid_default_addr_size): Relying on default #size-cells value for /spi-gpio/spi-gpio@0 #### make completed successfully (4 seconds) ####
Instalar el archivo dtb modificado
$ sudo fastboot flash dtb \ out/target/product/odroidc2/obj/KERNEL_OBJ/arch/arm64/boot/dts/meson64_odroidc2.dtbTienes que editar el archivo /storage/internal/boot.ini para cargar una imagen alternativa del Kernel. Existe una imagen alternativa del kernel para usar los pines I2C con la función UART.
# movi read boot 0 ${loadaddr}
fatload mmc 0:1 ${loadaddr} Image_android
Editar ueventd.odroidc2.rc
Cambia el permiso de ttyS2 y ttyS3 para el acceso del sistema.
shell@odroidc2:/ $ su root@odroidc2:/ # mount -o rw,remount / [ 1243.002784@2] EXT4-fs (mmcblk0p2): re-mounted. Opts: (null) root@odroidc2:/ # vi /ueueventd.odroidc2.rc ueventd.rc root@odroidc2:/ # vi /ueventd.odroidc2.rc /dev/ttyS* 0666 system system
Configurar el código de ejemplo de la app de Android
Descarga la librería de WiringPi NDK de https://goo.gl/uuDeys, y el código fuente de la aplicación desde GitHub en https://goo.gl/YNXTUn.
$ sudo apt install git $ git clone https://github.com/codewalkerster/example-wiringPi -b odroid-c_3_uart
Para comentarios, preguntas y sugerencias, visita el post original en https://goo.gl/jteQuV.
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