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--- en:c2_hardware_uart [2016/02/29 16:02]
ck.kim
+++ en:c2_hardware_uart [2017/01/31 13:16] (current)
brian.kim
@@ Line 1: / Line 1: @@
 ====== UART interface using the Tinkering Kit ======
-There are two UART ports on the C2.
+There are two UART ports on the C2. \\
+They are 3.3Volt (LVTTL) interface and there is no 5Volt tolerance.
+The first one is mapped to /dev/ttyS1 which is connected to 40-pin header Pin #8 & #10 & ground pin.\\
-The first one is mapped to /dev/ttyS1 which is connected to 40-pin header Pin #8 & #10.\\
 The second one is mapped to /dev/ttyS0 which is connected to Serial Console Port CON5.
-=== How to test external UART pin on the 40-pin header ===
+==== How to test external UART pin on the 40-pin header ====
 You need to prepare below items.
@@ Line 44: / Line 44: @@
 Send characters via minicom.
-=== Pin Map : UART pin on the 4-pin CON5 connector ===
+==== Pin Map : UART pin on the 4-pin CON5 connector ====
 <code>
 _____UART____
@@ Line 56: / Line 56: @@
 </code>
 .3V LVTTL
+==== Another UART port on 40pin header ====
+If you don't use an I2C interface(i2c-1) on pin#3 & pin#5, you can use them to activate the UART2.\\
+Just follow **campbell**'s development note to have a new UART2 port via /dev/ttyS2.\\
+Note that Pin#3(SDA1) is mapped to Tx and Pin#5(SCL1) is Rx.\\
+[[http://forum.odroid.com/viewtopic.php?f=139&t=25371|How to enable a third UART ttyS2 by "campbell"]]
+==== Automatically configure the UART settings. ====
+This is an example of default setting for a GPS module which has a 9600bpsN81 UART interface.\\
+Add the following to the end of /etc/rc.local (before the exit 0)\\
+<code>/bin/stty -F /dev/ttyS2 raw 9600 cs8 clocal -cstopb > /dev/null 2>&1</code>
+This way the tty port is setup for use with the gps on system boot, without user interaction.\\
 === Tips for UART port ===
 [[http://forum.odroid.com/viewtopic.php?f=115&t=17279|How to enable the RTS/CTS]]
+==== How to enable UART_B and UART_C ports ====
+Up to 4 ports can be used for UART in ODROID-C2---UART_A0(Serial console), UART_A, UART_B and UART_C.\\
+There are UART_A, UART_B and UART_C in [[http://odroid.com/dokuwiki/doku.php?id=en:c2_hardware#expansion_connectors|expansion connectors of ODROID-C2]].
+  * //<UART pin>// | //<Pin number>//
+  * UART_A TX | 8
+  * UART_A RX | 10
+  * UART_B TX | 3
+  * UART_B RX | 5
+  * UART_C TX | 32
+  * UART_C RX | 26
+In order to enable UART_B and UART_C ports, it is necessary to modify the //meson64_odroidc2.dts// file.
+. Kernel source download
+<code>
+sudo apt-get update
+sudo apt-get install git
+git clone --depth 1 https://github.com/hardkernel/linux.git -b odroidc2-3.14.y
+</code>
+. Delete I2C_A definition
+I2C_A uses same pins as UART_B by pinmux. So, i2c_a definition needs to be removed.
+  * //($LINUX)/arch/arm64/boot/dts/meson64_odroidc2.dts//
+<code>
+iff --git a/arch/arm64/boot/dts/meson64_odroidc2.dts b/arch/arm64/boot/dts/meson64_odroidc2.dts
+index e6a25b0..db09b04 100755
+--- a/arch/arm64/boot/dts/meson64_odroidc2.dts
++++ b/arch/arm64/boot/dts/meson64_odroidc2.dts
+@@ -813,18 +813,6 @@
+ };
+-&i2c_a {
+-       status = "okay";
+-
+-       /* Hardkernel I2C RTC */
+-       pcf8563: pcf8563@51     {
+-               status = "disabled";
+-               compatible = "nxp,pcf8563";
+-               reg = <0x51>;
+-               #clock-cells = <0>;
+-       };
+-};
+-
+ &i2c_b {
+        status = "okay";
+</code>
+. Add UART_B and UART_C definitions
+  * //($LINUX)/arch/arm64/boot/dts/meson64_odroidc2.dts//
+<code>
+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";
+</code>
+  * [[https://gist.githubusercontent.com/bkrepo/ae548109e3f94fd41fed2defa270057b/raw/b50265071e0c4bfe22fcc418aba938bf843bfa8a/meson64_odroidc2.dts|meson64_odroidc2.dts]]
+. Install modified dtb file
+<code>
+make odroidc2_defconfig
+make dtbs
+sudo cp -f arch/arm64/boot/dts/meson64_odroidc2.dtb /media/boot/
+sudo reboot
+</code>
+. Done