Merge pull request #14834 from JannesVolkens/restore_CAN_README

tests/conn_can: Add to README

tests/conn_can/README.md

@@ -3,6 +3,59 @@ tests/conn_can
 Demo application for the CAN stack with conn_can interface.
 
 
+Native prerequisites
+============
+For using the can stack on top of socketCAN, available for linux, you need:
+- socketCAN (part of kernel starting from 2.6.25)
+- install  the 32bit version of libsocketcan:
+
+if you're on a 64bit system:
+```
+sudo dpkg --add-architecture i386
+sudo apt-get update
+sudo apt-get install libsocketcan-dev:i386
+```
+On 32 bit you can just do the following:
+```
+sudo apt-get install libsocketcan-dev
+```
+
+Alternatively, you can compile from source:
+```
+wget http://www.pengutronix.de/software/libsocketcan/download/libsocketcan-0.0.11.tar.bz2
+
+$ tar xvjf libsocketcan-0.0.11.tar.bz2
+
+$ rm -rf libsocketcan-0.0.11.tar.bz2
+
+$ cd libsocketcan-0.0.11
+
+$ ./configure
+
+compile in 32bits
+
+./configure --build=i686-pc-linux-gnu "CFLAGS=-m32" "CXXFLAG
+
+$ make
+
+$ sudo make install
+
+
+sudo ldconfig
+/usr/local/lib
+```
+
+The default native configuration defines two virtual can ifaces to be used.
+Before running this test on native, you should create those:
+
+```
+sudo modprobe vcan
+sudo ip link add dev vcan0 type vcan
+sudo ip link add dev vcan1 type vcan
+sudo ip link set vcan0 up
+sudo ip link set vcan1 up
+```
+
 Usage
 =====
 
@@ -84,3 +137,36 @@ sampling point 87.5%:
 ```
 test_can set_bitrate 250000 875
 ```
+
+Linux CAN basic commands
+========================
+
+Once the interfaces are set up, can-utils commands provide a way to send and receive
+raw CAN frames and ISO-TP datagrams.
+
+For ISO-TP, an experimental module for linux can be found [here](https://github.com/hartkopp/can-isotp).
+It needs to be loaded before trying to use ISO-TP protocol.
+
+Here are some basics examples.
+
+Send a raw CAN frame, id 0x100, data 00 11 22:
+```
+cansend vcan0 100#001122
+```
+
+Dump the traffic on a CAN interface:
+```
+candump vcan0
+```
+
+Send an ISO-TP datagram, source id 700, dest id 708, data 00 11 22 33 aa bb cc dd:
+```
+echo 00 11 22 33 aa bb cc dd | isotpsend -s 700 -d 708 vcan0
+```
+
+Receive ISO-TP datagram:
+```
+isotprecv -s 708 -d 700 vcan0
+```
+
+Please read commands help for more details on usage.