Add ptp4l usage

Timestamp-Synchronization.md

@@ -46,7 +46,7 @@ Connect Livox LiDAR/Hub normally without additional wiring.
 
 ### 2.1.2 Attention
 
-Network environments with multiple master clocks are not supported. For the construction of master clock, please refer to Appendix [3.1 Set Up PTP Master Clock](#3.1).
+Network environments with multiple master clocks are not supported. For the construction of master clock, please refer to Appendix [3.1 Set Up PTP Master Clock](#3.1 Set Up PTP Master Clock).
 
 ### 2.1.3 Accuracy
 
@@ -182,51 +182,38 @@ LiDAR_time_last = LiDAR_time;
 
 ## 3.1 Set Up PTP Master Clock
 
-Address: [https://github.com/ptpd/ptpd](https://github.com/ptpd/ptpd)
+Address: [http://linuxptp.sourceforge.net](http://linuxptp.sourceforge.net)
 
 Download, compile and install:
 
 ```bash
-git clone https://github.com/ptpd/ptpd.git
+git clone http://git.code.sf.net/p/linuxptp/code linuxptp
-autoreconf -vi
+cd linuxptp
-./configure
 make
-make install
+sudo make install
 ```
 
-Modify the configuration file client-e2e-socket.conf in the test folder according to your needs. You can use the following configuration:
+In order to run this software, you need Linux kernel version 3.0 or newer. Check whether your network interface supports PTP with the following command(example, network interface is 'eth0'). 
-
-Add a network interface name, such as eth0:
-
-```
-; Network interface to use (required)
-ptpengine:interface = eth0
-```
-
-Set the master clock function and set the parameters to masteronly:
-
-```
-; Options: none slaveonly masteronly masterslave 
-ptpengine:preset = masteronly
-```
-
-Set clock_class to a value lower than 128:
-
-```
-; Clock class - announced in master state. Always 255 for slave-only mode.
-; Minimum, maximum and default values are controlled by presets.
-; If set to 13 (application specific time source), announced 
-; time scale is always set to ARB. This setting controls the
-; states a PTP port can be in. If below 128, port will only
-; be in MASTER or PASSIVE states (master only). If above 127,
-; port will be in MASTER or SLAVE states.
-ptpengine:clock_class = 126
-```
-
-Then run the following command:
 
 ```bash
-ptpd2 -c test/client-e2e-socket.conf
+ethtool -T eth0
 ```
 
-When a sync packet appears on the network, it indicates that the master clock of ptpd is successfully turned on.
+This command shows whether a MAC supports hardware or software time stamping.
+
+The following example output indicates support for hardware time stamping. 
+
+![](./images/support.png)
+
+The following example output indicates network interface not support for linuxptp/ptp4l, cannot be used.
+
+![](./images/not_support.png)
+
+ If MAC supports hardware time stamping, then run the following command:
+
+```bash
+sudo ptp4l -i eth0 -l 6 -m
+```
+
+When a sync packet appears on the network, it indicates that the master clock of ptp4l is successfully turned on.
+